Ti-6Al-4V(TC4)used in dentistry and orthopedics as implant biomaterial faces the risk of microbiologically influenced corrosion(MIC)owing to the residence of diverse oral microorganisms.Hereinto,Streptococcus mutans i...Ti-6Al-4V(TC4)used in dentistry and orthopedics as implant biomaterial faces the risk of microbiologically influenced corrosion(MIC)owing to the residence of diverse oral microorganisms.Hereinto,Streptococcus mutans is a critical pathogenic microorganism that causes dental caries.This work investigated the corrosive effects of S.mutans on TC4 and functional gradient TC4/TC4-5Cu coupons fabricated by selective laser melting(SLM)through various electrochemical measurements,surface examination,observation of biofilm and corrosion analysis.The results indicated that the Cu-bearing alloy showed an inhibitory effect on the biofilms due to the release of Cu element,thereby reducing the corrosion rate of MIC.The corrosion current density(icorr)of TC4(11.7±0.8)nA cm−2 is higher than that of TC4/TC4-5Cu(7.4±0.4)nA cm−2 in the presence of S.mutans,while the maximum pit depth of TC4 is 1.6 times that of TC4/TC4-5Cu.Therefore,metal modification through Cu alloying is an effective strategy to improve the MIC resistance.展开更多
The world will benefit from more effective antimicrobial agents against oral conditions arising from the actions of biofilm forming bacteria. Also, information is lacking on the oral biofilm-forming bacterial diversit...The world will benefit from more effective antimicrobial agents against oral conditions arising from the actions of biofilm forming bacteria. Also, information is lacking on the oral biofilm-forming bacterial diversity in Southwestern Nigeria. In this study, we isolate and characterize oral biofilm producing bacteria in the oral cavities of schoolchildren in Southwestern Nigeria. We also investigate the antimicrobial properties of Macrosphyra longistyla extracts against the biofilm-formers and the toxicity of potent extracts. Samples were obtained from 109 schoolchildren aged 4 - 14 years from Lagos, Oyo and Osun States. Agar well diffusion technique was used in the antimicrobial susceptibility testing. Toxicity testing was done using brine shrimps (Artemia salina). Biofilm-formers in this study are Klebsiella sp., Streptococcus sp., Staphylococcus sp., and Micrococcus sp. Ethanol leaf extracts had the highest activity against all biofilm-producing bacteria. Ethanol stem bark extract, which elicited activity against Klebsiella only, was found to be less toxic than the ethanol leaf extract. Staphylococcus showed >10 mm susceptibility to the ethanol and aqueous extracts of Macrosphyra longistyla. Streptococcus and Micrococcus were susceptible to the antimicrobial actions of the ethanolic leaf extracts. Although the ethanol extracts of the leaves had lower minimum inhibitory concentrations than the ethanol extracts of the stem bark, toxicity studies showed ethanol extracts of the stem-bark to be more toxic than the ethanol extracts of the leaves. In conclusion, ethanolic extracts of Macrosphyra longistyla show potential as sources of antimicrobials against gram-positive, oral biofilm-forming bacteria.展开更多
Some bacteria have the ability to co-exist, proliferate and survive in a multicellular community, biofilm. Each participating bacteria can form its colonies and encases itself by a self-produced insoluble extracellula...Some bacteria have the ability to co-exist, proliferate and survive in a multicellular community, biofilm. Each participating bacteria can form its colonies and encases itself by a self-produced insoluble extracellular matrix substance (EPS). Microcolonies within biofilm are held together by interactions and bonding of the substances present in the EPS with their separation from the water channels. Similar to insoluble EPS, bacterial microcolonies release soluble exofactors that have direct impacts on the survivability, growth and antibacterial resistivity of other microcolonies made of single- or multi-species bacteria in the same biofilm. How the exofactors of microcolonies of one-type bacteria impact on microcolonies of other-type bacteria is still unclear. We studied about the role of exofactors released from Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa, which are common biofilm-forming pathogenic bacteria. Exofactors facilitate to transform the microenvironment where bacteria can acquire alternative lifestyle with a long survival period and resistivity to certain antimicrobial drugs.展开更多
To explore the role of biofilm formation on the corrosion of marine concrete structures, we investigated the attachment of biofilm on mortar surfaces in simulated seawater and the influence of biofilm on the microstru...To explore the role of biofilm formation on the corrosion of marine concrete structures, we investigated the attachment of biofilm on mortar surfaces in simulated seawater and the influence of biofilm on the microstructure of mortar surfaces. The results show that the evolution of biofilm on mortar surfaces in simulated seawater is closely related to the corrosion suffered by the mortar, and the process of biofilm attachment and shedding is continuous and cyclical. It is found that the specimens in the absence of biofilm attachment are more severely eroded internally by the corrosive medium in simulated seawater than those in the presence of biofilm attachment. For the specimens without biofilm attachment, after 60 days, gypsum forms,and after 120 days, the number of pores in the mortar is reduced. In contrast, for the specimens in the presence of biofilm attachment, gypsum could only be detected after 90 days, and fewer pores are filled. Therefore, the formation of biofilm could delay the invasion of the corrosive medium into the interior of mortar during the evolution of biofilm on mortar surfaces, mitigating the corrosion of mortars in seawater.展开更多
Slightly acidic electrolyzed water(SAEW)has proven to be an efficient and novel sanitizer in food and agriculture field.This study assessed the efficacy of SAEW(30 mg/L)at 40℃on the inactivation of foodbome pathogens...Slightly acidic electrolyzed water(SAEW)has proven to be an efficient and novel sanitizer in food and agriculture field.This study assessed the efficacy of SAEW(30 mg/L)at 40℃on the inactivation of foodbome pathogens and detachment of multi-resistant Staphylococcus aureus(MRSA)biofilm.Furthermore.the underlying mechanism of MRS A biofilm under heated SAEW at 40℃treatment on metabolic profiles was investigated.The results showed that the heated SAEW at 40℃significantly effectively against foodbome pathogens of 1.96-7.56(lg(CFU/g))reduction in pork,chicken,spinach,and lettuce.The heated SAEW at 40℃treatment significantly reduced MRS A biofilm cells by 2.41(lg(CFU/cm^(2))).The synergistic effect of SAEW treatment showed intense anti-biofilm activity in decreasing cell density and impairing biofilm cell membranes.Global metabolic response of MRSA biofilms,treated by SAEW at 40℃,revealed the alterations of intracellular metabolites,including amino acids,organic acid,fatty acid,and lipid.Moreover,signaling pathways involved in amino acid metabolism,energy metabolism,nucleotide synthesis,carbohydrate metabolites,and lipid biosynthesis were functionally disrupted by the SAEW at 40℃treatment.As per our knowledge,this is the first research to uncover the potential mechanism of heated SAEW treatment against MRSA biofilm on food contact surface.展开更多
Dysregulation of G9a,a histone-lysine N-methyltransferase,has been observed in Alzheimer’s disease and has been correlated with increased levels of chronic inflammation and oxidative stress.Likewise,microRNAs are inv...Dysregulation of G9a,a histone-lysine N-methyltransferase,has been observed in Alzheimer’s disease and has been correlated with increased levels of chronic inflammation and oxidative stress.Likewise,microRNAs are involved in many biological processes and diseases playing a key role in pathogenesis,especially in multifactorial diseases such as Alzheimer’s disease.Therefore,our aim has been to provide partial insights into the interconnection between G9a,microRNAs,oxidative stress,and neuroinflammation.To better understand the biology of G9a,we compared the global microRNA expression between senescence-accelerated mouse-prone 8(SAMP8)control mice and SAMP8 treated with G9a inhibitor UNC0642.We found a downregulation of miR-128 after a G9a inhibition treatment,which interestingly binds to the 3′untranslated region(3′-UTR)of peroxisome-proliferator activator receptor γ(PPARG)mRNA.Accordingly,Pparg gene expression levels were higher in the SAMP8 group treated with G9a inhibitor than in the SAMP8 control group.We also observed modulation of oxidative stress responses might be mainly driven Pparg after G9a inhibitor.To confirm these antioxidant effects,we treated primary neuron cell cultures with hydrogen peroxide as an oxidative insult.In this setting,treatment with G9a inhibitor increases both cell survival and antioxidant enzymes.Moreover,up-regulation of PPARγby G9a inhibitor could also increase the expression of genes involved in DNA damage responses and apoptosis.In addition,we also described that the PPARγ/AMPK axis partially explains the regulation of autophagy markers expression.Finally,PPARγ/GADD45αpotentially contributes to enhancing synaptic plasticity and neurogenesis after G9a inhibition.Altogether,we propose that pharmacological inhibition of G9a leads to a neuroprotective effect that could be due,at least in part,by the modulation of PPARγ-dependent pathways by miR-128.展开更多
In this article dedicated to the modeling of vertical mass transfers between the biofilm and the bulk flow, we have, in the first instance, presented the methodology used, followed by the presentation of various resul...In this article dedicated to the modeling of vertical mass transfers between the biofilm and the bulk flow, we have, in the first instance, presented the methodology used, followed by the presentation of various results obtained through analyses conducted on velocity fields, different fluxes, and overall transfer coefficients. Due to numerical constraints (resolution of relevant spatial scales), we have restricted the analysis to low Schmidt numbers (S<sub>c</sub><sub></sub>=0.1, S<sub>c</sub></sub>=1, and S<sub>c</sub></sub>=10) and a single roughness Reynolds number (Re<sub>*</sub>=150). The analysis of instantaneous concentration fields from various simulations revealed logarithmic concentration profiles above the canopy. In this zone, the concentration is relatively homogeneous for longer times. The analysis of results also showed that the contribution of molecular diffusion to the total flux depends on the Schmidt number. This contribution is negligible for Schmidt numbers S<sub>c</sub></sub>≥0.1, but nearly balances the turbulent flux for S<sub>c</sub></sub>=0.1. In the canopy, the local Sherwood number, given by the ratio of the total flux (within or above the canopy) to the molecular diffusion flux at the wall, also depends on the Schmidt number and varies significantly between the canopy and the region above. The exchange velocity, a purely hydrodynamic parameter, is independent of the Schmidt number and is on the order of 10% of in the present case. This study also reveals that nutrient absorption by organisms near the wall depends on the Schmidt number. Such absorption is facilitated by lower Schmidt numbers.展开更多
Objective:To investigate the effect of TSH inhibition therapy in the postoperative management of patients with differentiated thyroid cancer.Methods:Seventy patients diagnosed with differentiated thyroid cancer were s...Objective:To investigate the effect of TSH inhibition therapy in the postoperative management of patients with differentiated thyroid cancer.Methods:Seventy patients diagnosed with differentiated thyroid cancer were selected for the study.TSH inhibition therapy was administered to the research group,while thyroxine replacement therapy was provided to the control group during the postoperative management phase.This allowed for a comparative analysis between the two groups.Results:In comparison with the control group,the research group exhibited significant decreases in serum TSH,T3,and T4 levels after treatment,while FT4 and FT3 levels significantly increased(P<0.05).Additionally,significant decreases in Tg,VEGF,TSGF,CD44V6,and sIL-2R levels were observed in the research group after treatment(P<0.05).No significant differences were found in pre-treatment thyroid function between the two groups(P>0.05).Conclusion:The application of TSH inhibition therapy in the postoperative management of patients with differentiated thyroid cancer demonstrates promising outcomes.展开更多
Biofilm plays an important role on microbial corrosion and biofouling in marine environments.Inhibiting biofilm formation on construction surfaces is of great importance.Photocatalytic material with visiblelight respo...Biofilm plays an important role on microbial corrosion and biofouling in marine environments.Inhibiting biofilm formation on construction surfaces is of great importance.Photocatalytic material with visiblelight response,especially BiVO_(4),is regarded as a promising material for biofilm inhibition due to its green biocidal effect and high antibacterial efficiency.Approaches which can immobilize the photocatalytic particles onto metal surfaces with high mechanical strength are requisite.In this study,zinc matrixes were served as carriers for BiVO_(4)particles.The BiVO_(4)-inserted zinc matrixes were successfully obtained by ultrasound assisted electrodeposition.The insertion content of BiVO_(4)showed positive correlation with ultrasound power.Highly enhanced biofilm inhibition properties were obtained by BiVO_(4)inserted zinc·matrixes with an over 95%decreased bacterial coverage.It was proved that O2-(chief)andOH(subordinate)radicals were responsible for the high biocidal performance.Possible antibacterial mechanism was proposed,indicating that the photoinduced holes would both attack zinc crystals to generate active electrons to form O2-radicals,and react with H2 O to generate·OH,finally.Furthermore,corrosion resistance of the matrixes was proved to be stable due to the insertion of BiVO_(4).This study provides a potential application for photocatalyst in marine antifouling and anti-biocorrosion aspects.展开更多
304 stainless steel(SS) used as orthodontic wire during orthodontics faces the risk of microbiologically influenced corrosion(MIC) due to diverse flora environment. Hereinto, Streptococcus mutans(S. mutans)is the most...304 stainless steel(SS) used as orthodontic wire during orthodontics faces the risk of microbiologically influenced corrosion(MIC) due to diverse flora environment. Hereinto, Streptococcus mutans(S. mutans)is the most important cariogenic bacteria. In this work, MIC behavior of a new 304-Cu SS in presence of S. mutans was studied by the observations using scanning electron microscopy(SEM) and confocal laser scanning microscopy(CLSM) including live/dead staining, extracellular polymeric substance(EPS)staining and pitting corrosion, electrochemical test, and X-ray photoelectron spectroscopy(XPS). Above results showed that 304-Cu SS possessed excellent biofilm inhibition ability and presented lower corrosion current density(icorr), larger polarization resistance(Rp) and charge transfer resistance(Rct) in the presence of S. mutans, indicating that 304-Cu SS had a better MIC resistance against S. mutans. It was further affirmed by XPS results that the presence of Cu-oxide in passive film of 304-Cu SS inhibited the formation of biofilm.展开更多
Alkali production by oral bacteria is believed to have a major impact on oral microbial ecology and to be inibitory to the initiation and progression of dental caries.A substantial body of evidence is beginning to acc...Alkali production by oral bacteria is believed to have a major impact on oral microbial ecology and to be inibitory to the initiation and progression of dental caries.A substantial body of evidence is beginning to accumulate that indicates the modulation of the alkalinogenic potential of dental biofilms may be a promising strategy for caries control.This brief review highlights recent progress toward understanding molecular genetic and physiologic aspects of important alkali-generating pathways in oral bacteria,and the role of alkali production in the ecology of dental biofilms in health and disease.展开更多
Corrosion inhibition of stainless steel due to a sulfate-reducing bacteria (SRB) biofilm in seawater was studied. By atomic force microscopy, a layer of fish-scale-like biofilm was found to form as stainless steel cou...Corrosion inhibition of stainless steel due to a sulfate-reducing bacteria (SRB) biofilm in seawater was studied. By atomic force microscopy, a layer of fish-scale-like biofilm was found to form as stainless steel coupons were exposed to the culture media with SRB, and this biofilm grew more and more compact. As a result, coupons' surface under the biofilm turned irregular less slowly than that exposed to the sterilized culture media. Then, physicoelectric characteristics of the electrode/biofilm/solution interface were investigated by electrochemical impedance spectroscopy (EIS), and the coverage of the biofilm as well as the relative irregularity of coupons' surface was also recorded by EIS spectra. Finally, anodic cyclic polarization results further demonstrated the protective property of the biofilm. Therefore, in estimation of SRB-implicated corrosion of stainless steel, not only the detrimental SRB metabolites but also the protective SRB biofilm as well should be taken into account.展开更多
Pig Actinobacillus pleuropneumoniae(App) could induce chronic respiratory tract infection in pigs, which causes major economic losses on pig industry. Bacterial biofilm(BBF) is bacterial community adsorbed on the surf...Pig Actinobacillus pleuropneumoniae(App) could induce chronic respiratory tract infection in pigs, which causes major economic losses on pig industry. Bacterial biofilm(BBF) is bacterial community adsorbed on the surface of biomaterials or body cavity, to protect bacteria escape, and recurrent outbreaks of related infectious diseases and chronic infections resulting therefrom are called bacterial biofilm diseases. App BF belongs to polymers with spatial structure in vitro, and its formation is regulated by multiple genes. Among them, gene deletion of the key component TolC of multidrug efflux pumps and type I secretion systems causes that App BF adhesion weakens; gene deletion of catalytic core ClpP of Clp proteolytic complex induces the inhibition of BF formation; outer membrane lipoprotein VacJ of App promotes BF formation; gene deletion of active enzyme LuxS enhances the formation of App BF and decreases bacterial adhesion ability; gene deletion of Adh obviously declines bacterial accumulation, BF formation and adhesion to host cells. In this paper, BF formation or inhibition mechanism in App is elaborated from molecular level, which could provide reference basis for exploring the prevention of its biofilm diseases.展开更多
Fibroblast activation protein(Fap)is a serine protease that degrades denatured type I collagen,α2-antiplasmin and FGF21.Fap is highly expressed in bone marrow stromal cells and functions as an osteogenic suppressor a...Fibroblast activation protein(Fap)is a serine protease that degrades denatured type I collagen,α2-antiplasmin and FGF21.Fap is highly expressed in bone marrow stromal cells and functions as an osteogenic suppressor and can be inhibited by the bone growth factor Osteolectin(Oln).Fap is also expressed in synovial fibroblasts and positively correlated with the severity of rheumatoid arthritis(RA).However,whether Fap plays a critical role in osteoarthritis(OA)remains poorly understood.Here,we found that Fap is significantly elevated in osteoarthritic synovium,while the genetic deletion or pharmacological inhibition of Fap significantly ameliorated posttraumatic OA in mice.Mechanistically,we found that Fap degrades denatured type II collagen(Col II)and Mmp13-cleaved native Col II.Intra-articular injection of r Fap significantly accelerated Col II degradation and OA progression.In contrast,Oln is expressed in the superficial layer of articular cartilage and is significantly downregulated in OA.Genetic deletion of Oln significantly exacerbated OA progression,which was partially rescued by Fap deletion or inhibition.Intra-articular injection of r Oln significantly ameliorated OA progression.Taken together,these findings identify Fap as a critical pathogenic factor in OA that could be targeted by both synthetic and endogenous inhibitors to ameliorate articular cartilage degradation.展开更多
Biofilms act as a reservoir of infection, and periodically release cells in vicinity that are capable of developing new biofilm colonies and disseminate infection. Many chronic bacterial infections are serious that ar...Biofilms act as a reservoir of infection, and periodically release cells in vicinity that are capable of developing new biofilm colonies and disseminate infection. Many chronic bacterial infections are serious that are associated with biofilms and have high morbidity and mortality, partly due to their higher resistance to antimicrobial agents, and partly due to lack of strong biocides which can efficiently treat and inhibit biofilm formation. We recently demonstrated that nonequilibrium non-thermal dielectric-barrier discharge plasma (Plasma) can also be applied to control pathogens via applying treated-liquids, and these liquids acquire broad-spectrum antimicrobial properties. In present studies we demonstrated a range of plasma-activated simple chemical solutions which significantly inhibited biofilm formation by multidrug-resistant bacterial pathogens. Plasma-activated methionine solution exhibited strong inhibitory activity against the biofilms of car-bapenem-resistant Acinetobacter baumannii, methicillin-resistant Staphylococcus aureus, metal-lo-β-lactamase (NDM1)-positive Klebsiella pneumoniae, and Enterococcus faecalis, and prevented the formation of biofilms by about 70% as compared to untreated controls in single exposure. In addition to inhibition of biofilm formation, a complete inactivation of biofilm-embedded bacterial cells was observed in less than 30 minute’s exposure to candidate plasma-activated methionine solution. These findings suggest that plasma-activated solutions have a potential to prevent biofilm formation, and as biofilm inhibitor.展开更多
The additive manufacturing(AM)of Ni-based superalloys has attracted extensive interest from both academia and industry due to its unique capabilities to fabricate complex and high-performance components for use in hig...The additive manufacturing(AM)of Ni-based superalloys has attracted extensive interest from both academia and industry due to its unique capabilities to fabricate complex and high-performance components for use in high-end industrial systems.However,the intense temperature gradient induced by the rapid heating and cooling processes of AM can generate high levels of residual stress and metastable chemical and structural states,inevitably leading to severe metallurgical defects in Ni-based superalloys.Cracks are the greatest threat to these materials’integrity as they can rapidly propagate and thereby cause sudden and non-predictable failure.Consequently,there is a need for a deeper understanding of residual stress and cracking mechanisms in additively manufactured Ni-based superalloys and ways to potentially prevent cracking,as this knowledge will enable the wider application of these unique materials.To this end,this paper comprehensively reviews the residual stress and the various mechanisms of crack formation in Ni-based superalloys during AM.In addition,several common methods for inhibiting crack formation are presented to assist the research community to develop methods for the fabrication of crack-free additively manufactured components.展开更多
Objective:To characterize biofilm production by clinical(n=21)and environmental(n=11)isolates of Burkholderia pseudomallei and evaluate the production of proteases,hemolysins and siderophores.Methods:Initially,the 32 ...Objective:To characterize biofilm production by clinical(n=21)and environmental(n=11)isolates of Burkholderia pseudomallei and evaluate the production of proteases,hemolysins and siderophores.Methods:Initially,the 32 strains were evaluated for biofilm production in Müller-Hinton broth-1%glucose(MH-1%glucose)and BHI broth-1%glucose,using the crystal violet staining technique.Subsequently,growing(48 h)and mature(72 h)biofilms were evaluated by confocal microscopy.Finally,the production of proteases,hemolysins and siderophores by planktonic aggregates,growing biofilms and mature biofilms was evaluated.Results:All isolates produced biofilms,but clinical isolates had significantly higher biomass in both MH-1%glucose(P<0.001)and BHI-glucose 1%(P=0.005).The structural analyses by confocal microscopy showed thick biofilms,composed of multiple layers of cells,homogeneously arranged,with mature biofilms of clinical isolates presenting higher biomass(P=0.019)and thickness of the entire area(P=0.029),and lower roughness coefficient(P=0.007)than those of environmental isolates.Protease production by growing biofilms was significantly greater than that of planktonic(P<0.001)and mature biofilms(P<0.001).Hemolysin release by planktonic aggregates was higher than that of biofilms(P<0.001).Regarding siderophores,mature biofilms presented higher production than growing biofilms(P<0.001)and planktonic aggregates(P<0.001).Conclusions:Clinical isolates have higher production of biofilms than their environmental counterparts;protease and siderophores seem important for growth and maintenance of Burkholderia pseudomallei biofilms.展开更多
Salmonella and their biofilm formation are the primary bacterial causes of foodborne outbreaks and crosscontamination. The objective of the study was to investigate the potential of Salmonella phages as an alternative...Salmonella and their biofilm formation are the primary bacterial causes of foodborne outbreaks and crosscontamination. The objective of the study was to investigate the potential of Salmonella phages as an alternative technology for biofilm removal. In this work, 21 Salmonella phages were isolated from a chicken farm and slaughter plant and the phage(CW1)with the broadest spectrum was characterized. Complete genome sequence analysis revealed that the genomes of phage CW1 is composed of 41 763 bp with 58 open reading frames(ORFs)and a holin-endolysin system and it does not encode any virulence or lysogeny. A phage cocktail consisted of CW1(with the broadest spectrum of 70.49%)and CW11, M4 and M10(with a high lytic activity of more than 67.11%)was established. Treatment with the cocktail reduced the cells in the developing biofilm and mature biofilm by 0.79 lg(CFU/cm~2)and 0.4 lg(CFU/cm~2), respectively. More dead cells and scattered extracellular polymeric substances(EPS)were observed by confocal laser scanning microscopy and scanning electron microscopy. Raman analysis found that carbohydrates and proteins were the identification receptors for scattered EPS. This finding suggests that this phage cockta il has potential applications for the sterilization of Salmonella biofilm during meat processing.展开更多
Objective: This study focused on the antibacterial and anti-proliferative activity of extracts from Carica papaya and Cocos nucifera roots. Methodology: The minimum inhibitory concentration and the minimum bactericida...Objective: This study focused on the antibacterial and anti-proliferative activity of extracts from Carica papaya and Cocos nucifera roots. Methodology: The minimum inhibitory concentration and the minimum bactericidal concentration of the extracts on Escherichia coli, Pseudomonas aeruginosa, Streptococcus mutans, and Staphylococcus aureus were deduced by the microdilution method. The anti-biofilm activity was determined on all four strains and anti-quorum sensing activity by inhibition of violacein production in Chromobacterium violaceum. Anti-proliferative activity on prostate cultured cancer cells was evaluated by MTT assay. Sterols and triterpenes were also assayed in this study. Results: The methanolic extract of Carica papaya showed the best anti-biofilm effect with a percentage inhibition of 66.10 ± 1.79. The methanolic extract of Cocos nucifera had the strongest inhibition on the production of quorum sensing (61.42 ± 0.28). In addition, the methanolic extract of Cocos nucifera roots showed the best cytotoxic effect on prostate cancer LNCaP cell lines (IC<sub>50</sub> = 26.98 ± 2.6 μg/mL) and Carica papaya on the PC-3 lines (IC<sub>50</sub> = 127.20 ± 5.99 μg/mL). The extracts were also rich in triterpenes and sterols. Conclusion: This study provides support for the ethnomedical use of Carica papaya and Cocos nucifera roots as an antimicrobial and anticancer.展开更多
Denitrifying bacteria in epiphytic biofilms play a crucial role in nitrogen cycle in aquatic habitats.However,little is known about the connection between algae and denitrifying bacteria and their assembly processes i...Denitrifying bacteria in epiphytic biofilms play a crucial role in nitrogen cycle in aquatic habitats.However,little is known about the connection between algae and denitrifying bacteria and their assembly processes in epiphytic biofilms.Epiphytic biofilms were collected from submerged macrophytes(Patamogeton lucens and Najas marina L.)in the Caohai Lake,Guizhou,SW China,from July to November 2020 to:(1)investigate the impact of abiotic and biotic variables on denitrifying bacterial communities;(2)investigate the temporal variation of the algae-denitrifying bacteria co-occurrence networks;and(3)determine the contribution of deterministic and stochastic processes to the formation of denitrifying bacterial communities.Abiotic and biotic factors influenced the variation in the denitrifying bacterial community,as shown in the Mantel test.The co-occurrence network analysis unveiled intricate interactions among algae to denitrifying bacteria.Denitrifying bacterial community co-occurrence network complexity(larger average degrees representing stronger network complexity)increased continuously from July to September and decreased in October before increasing in November.The co-occurrence network complexity of the algae and nirS-encoding denitrifying bacteria tended to increase from July to November.The co-occurrence network complexity of the algal and denitrifying bacterial communities was modified by ammonia nitrogen(NH_(4)^(+)-N)and total phosphorus(TP),pH,and water temperature(WT),according to the ordinary least-squares(OLS)model.The modified stochasticity ratio(MST)results reveal that deterministic selection dominated the assembly of denitrifying bacterial communities.The influence of environmental variables to denitrifying bacterial communities,as well as characteristics of algal-bacterial co-occurrence networks and the assembly process of denitrifying bacterial communities,were discovered in epiphytic biofilms in this study.The findings could aid in the appropriate understanding and use of epiphytic biofilms denitrification function,as well as the enhancement of water quality.展开更多
基金supported by the National Natural Science Foundation of China(No.52301091)the Medical Engineering Intersection Joint Funds of the Natural Science Foundation of Liaoning Province of China(No.2022-YGJC-01).
文摘Ti-6Al-4V(TC4)used in dentistry and orthopedics as implant biomaterial faces the risk of microbiologically influenced corrosion(MIC)owing to the residence of diverse oral microorganisms.Hereinto,Streptococcus mutans is a critical pathogenic microorganism that causes dental caries.This work investigated the corrosive effects of S.mutans on TC4 and functional gradient TC4/TC4-5Cu coupons fabricated by selective laser melting(SLM)through various electrochemical measurements,surface examination,observation of biofilm and corrosion analysis.The results indicated that the Cu-bearing alloy showed an inhibitory effect on the biofilms due to the release of Cu element,thereby reducing the corrosion rate of MIC.The corrosion current density(icorr)of TC4(11.7±0.8)nA cm−2 is higher than that of TC4/TC4-5Cu(7.4±0.4)nA cm−2 in the presence of S.mutans,while the maximum pit depth of TC4 is 1.6 times that of TC4/TC4-5Cu.Therefore,metal modification through Cu alloying is an effective strategy to improve the MIC resistance.
文摘The world will benefit from more effective antimicrobial agents against oral conditions arising from the actions of biofilm forming bacteria. Also, information is lacking on the oral biofilm-forming bacterial diversity in Southwestern Nigeria. In this study, we isolate and characterize oral biofilm producing bacteria in the oral cavities of schoolchildren in Southwestern Nigeria. We also investigate the antimicrobial properties of Macrosphyra longistyla extracts against the biofilm-formers and the toxicity of potent extracts. Samples were obtained from 109 schoolchildren aged 4 - 14 years from Lagos, Oyo and Osun States. Agar well diffusion technique was used in the antimicrobial susceptibility testing. Toxicity testing was done using brine shrimps (Artemia salina). Biofilm-formers in this study are Klebsiella sp., Streptococcus sp., Staphylococcus sp., and Micrococcus sp. Ethanol leaf extracts had the highest activity against all biofilm-producing bacteria. Ethanol stem bark extract, which elicited activity against Klebsiella only, was found to be less toxic than the ethanol leaf extract. Staphylococcus showed >10 mm susceptibility to the ethanol and aqueous extracts of Macrosphyra longistyla. Streptococcus and Micrococcus were susceptible to the antimicrobial actions of the ethanolic leaf extracts. Although the ethanol extracts of the leaves had lower minimum inhibitory concentrations than the ethanol extracts of the stem bark, toxicity studies showed ethanol extracts of the stem-bark to be more toxic than the ethanol extracts of the leaves. In conclusion, ethanolic extracts of Macrosphyra longistyla show potential as sources of antimicrobials against gram-positive, oral biofilm-forming bacteria.
文摘Some bacteria have the ability to co-exist, proliferate and survive in a multicellular community, biofilm. Each participating bacteria can form its colonies and encases itself by a self-produced insoluble extracellular matrix substance (EPS). Microcolonies within biofilm are held together by interactions and bonding of the substances present in the EPS with their separation from the water channels. Similar to insoluble EPS, bacterial microcolonies release soluble exofactors that have direct impacts on the survivability, growth and antibacterial resistivity of other microcolonies made of single- or multi-species bacteria in the same biofilm. How the exofactors of microcolonies of one-type bacteria impact on microcolonies of other-type bacteria is still unclear. We studied about the role of exofactors released from Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa, which are common biofilm-forming pathogenic bacteria. Exofactors facilitate to transform the microenvironment where bacteria can acquire alternative lifestyle with a long survival period and resistivity to certain antimicrobial drugs.
基金Funded by the National Natural Science Foundation of China (Nos. 52278269, 52278268, 52178264, 52108238)Tianjin Outstanding Young Scholars Science Fund Project (No. 22JCJQJC00020)State Key Laboratory of Green Building Materials Open Foundation (No. 2021GBM08)。
文摘To explore the role of biofilm formation on the corrosion of marine concrete structures, we investigated the attachment of biofilm on mortar surfaces in simulated seawater and the influence of biofilm on the microstructure of mortar surfaces. The results show that the evolution of biofilm on mortar surfaces in simulated seawater is closely related to the corrosion suffered by the mortar, and the process of biofilm attachment and shedding is continuous and cyclical. It is found that the specimens in the absence of biofilm attachment are more severely eroded internally by the corrosive medium in simulated seawater than those in the presence of biofilm attachment. For the specimens without biofilm attachment, after 60 days, gypsum forms,and after 120 days, the number of pores in the mortar is reduced. In contrast, for the specimens in the presence of biofilm attachment, gypsum could only be detected after 90 days, and fewer pores are filled. Therefore, the formation of biofilm could delay the invasion of the corrosive medium into the interior of mortar during the evolution of biofilm on mortar surfaces, mitigating the corrosion of mortars in seawater.
基金supported by Brain Korea (BK)21 Plus Project (4299990913942)funded by the Korean Government,Koreathe Collabo Project funded by the Ministry of SMEs and Startups (C1016120-01-02)the National Research Foundation of Korea (NRF) (2018007551)。
文摘Slightly acidic electrolyzed water(SAEW)has proven to be an efficient and novel sanitizer in food and agriculture field.This study assessed the efficacy of SAEW(30 mg/L)at 40℃on the inactivation of foodbome pathogens and detachment of multi-resistant Staphylococcus aureus(MRSA)biofilm.Furthermore.the underlying mechanism of MRS A biofilm under heated SAEW at 40℃treatment on metabolic profiles was investigated.The results showed that the heated SAEW at 40℃significantly effectively against foodbome pathogens of 1.96-7.56(lg(CFU/g))reduction in pork,chicken,spinach,and lettuce.The heated SAEW at 40℃treatment significantly reduced MRS A biofilm cells by 2.41(lg(CFU/cm^(2))).The synergistic effect of SAEW treatment showed intense anti-biofilm activity in decreasing cell density and impairing biofilm cell membranes.Global metabolic response of MRSA biofilms,treated by SAEW at 40℃,revealed the alterations of intracellular metabolites,including amino acids,organic acid,fatty acid,and lipid.Moreover,signaling pathways involved in amino acid metabolism,energy metabolism,nucleotide synthesis,carbohydrate metabolites,and lipid biosynthesis were functionally disrupted by the SAEW at 40℃treatment.As per our knowledge,this is the first research to uncover the potential mechanism of heated SAEW treatment against MRSA biofilm on food contact surface.
基金supported by the Ministerio de Economía,Industria y Competitividad(Agencia Estatal de Investigación,AEI,to CGF and MP)Fondo Europeo de Desarrollo Regional(MINECO-FEDER)(PID2022-139016OA-I00,PDC2022-133441-I00,to CGF and MP),Generalitat de Catalunya(2021 SGR 00357+3 种基金to CGF and MP)co-financed by Secretaria d’Universitats i Recerca del Departament d’Empresai Coneixement de la Generalitat de Catalunya 2021(Llavor 00086,to CGF)the recipient of an Alzheimer’s Association Research Fellowship(AARF-21-848511)the Agència de Gestiód’Ajuts Universitaris i de Recerca(AGAUR)for her FI-SDUR fellowship(2021FISDU 00182).
文摘Dysregulation of G9a,a histone-lysine N-methyltransferase,has been observed in Alzheimer’s disease and has been correlated with increased levels of chronic inflammation and oxidative stress.Likewise,microRNAs are involved in many biological processes and diseases playing a key role in pathogenesis,especially in multifactorial diseases such as Alzheimer’s disease.Therefore,our aim has been to provide partial insights into the interconnection between G9a,microRNAs,oxidative stress,and neuroinflammation.To better understand the biology of G9a,we compared the global microRNA expression between senescence-accelerated mouse-prone 8(SAMP8)control mice and SAMP8 treated with G9a inhibitor UNC0642.We found a downregulation of miR-128 after a G9a inhibition treatment,which interestingly binds to the 3′untranslated region(3′-UTR)of peroxisome-proliferator activator receptor γ(PPARG)mRNA.Accordingly,Pparg gene expression levels were higher in the SAMP8 group treated with G9a inhibitor than in the SAMP8 control group.We also observed modulation of oxidative stress responses might be mainly driven Pparg after G9a inhibitor.To confirm these antioxidant effects,we treated primary neuron cell cultures with hydrogen peroxide as an oxidative insult.In this setting,treatment with G9a inhibitor increases both cell survival and antioxidant enzymes.Moreover,up-regulation of PPARγby G9a inhibitor could also increase the expression of genes involved in DNA damage responses and apoptosis.In addition,we also described that the PPARγ/AMPK axis partially explains the regulation of autophagy markers expression.Finally,PPARγ/GADD45αpotentially contributes to enhancing synaptic plasticity and neurogenesis after G9a inhibition.Altogether,we propose that pharmacological inhibition of G9a leads to a neuroprotective effect that could be due,at least in part,by the modulation of PPARγ-dependent pathways by miR-128.
文摘In this article dedicated to the modeling of vertical mass transfers between the biofilm and the bulk flow, we have, in the first instance, presented the methodology used, followed by the presentation of various results obtained through analyses conducted on velocity fields, different fluxes, and overall transfer coefficients. Due to numerical constraints (resolution of relevant spatial scales), we have restricted the analysis to low Schmidt numbers (S<sub>c</sub><sub></sub>=0.1, S<sub>c</sub></sub>=1, and S<sub>c</sub></sub>=10) and a single roughness Reynolds number (Re<sub>*</sub>=150). The analysis of instantaneous concentration fields from various simulations revealed logarithmic concentration profiles above the canopy. In this zone, the concentration is relatively homogeneous for longer times. The analysis of results also showed that the contribution of molecular diffusion to the total flux depends on the Schmidt number. This contribution is negligible for Schmidt numbers S<sub>c</sub></sub>≥0.1, but nearly balances the turbulent flux for S<sub>c</sub></sub>=0.1. In the canopy, the local Sherwood number, given by the ratio of the total flux (within or above the canopy) to the molecular diffusion flux at the wall, also depends on the Schmidt number and varies significantly between the canopy and the region above. The exchange velocity, a purely hydrodynamic parameter, is independent of the Schmidt number and is on the order of 10% of in the present case. This study also reveals that nutrient absorption by organisms near the wall depends on the Schmidt number. Such absorption is facilitated by lower Schmidt numbers.
文摘Objective:To investigate the effect of TSH inhibition therapy in the postoperative management of patients with differentiated thyroid cancer.Methods:Seventy patients diagnosed with differentiated thyroid cancer were selected for the study.TSH inhibition therapy was administered to the research group,while thyroxine replacement therapy was provided to the control group during the postoperative management phase.This allowed for a comparative analysis between the two groups.Results:In comparison with the control group,the research group exhibited significant decreases in serum TSH,T3,and T4 levels after treatment,while FT4 and FT3 levels significantly increased(P<0.05).Additionally,significant decreases in Tg,VEGF,TSGF,CD44V6,and sIL-2R levels were observed in the research group after treatment(P<0.05).No significant differences were found in pre-treatment thyroid function between the two groups(P>0.05).Conclusion:The application of TSH inhibition therapy in the postoperative management of patients with differentiated thyroid cancer demonstrates promising outcomes.
基金the financial support of the project from the National Natural Science Foundation of China(No.41706080 and 51702328)the Key Research Program of Frontier Sciences,CAS(ZDBS-LY-DQC025)+2 种基金the National Natural Science Foundation of China for Exploring Key Scientific Instrument(No.41827805)the Basic Scientific Fund for National Public Research Institutes of China(2019Y03 and 2020S02)the Open Fund of Shandong Key Laboratory of Corrosion Science(KLCS201906)。
文摘Biofilm plays an important role on microbial corrosion and biofouling in marine environments.Inhibiting biofilm formation on construction surfaces is of great importance.Photocatalytic material with visiblelight response,especially BiVO_(4),is regarded as a promising material for biofilm inhibition due to its green biocidal effect and high antibacterial efficiency.Approaches which can immobilize the photocatalytic particles onto metal surfaces with high mechanical strength are requisite.In this study,zinc matrixes were served as carriers for BiVO_(4)particles.The BiVO_(4)-inserted zinc matrixes were successfully obtained by ultrasound assisted electrodeposition.The insertion content of BiVO_(4)showed positive correlation with ultrasound power.Highly enhanced biofilm inhibition properties were obtained by BiVO_(4)inserted zinc·matrixes with an over 95%decreased bacterial coverage.It was proved that O2-(chief)andOH(subordinate)radicals were responsible for the high biocidal performance.Possible antibacterial mechanism was proposed,indicating that the photoinduced holes would both attack zinc crystals to generate active electrons to form O2-radicals,and react with H2 O to generate·OH,finally.Furthermore,corrosion resistance of the matrixes was proved to be stable due to the insertion of BiVO_(4).This study provides a potential application for photocatalyst in marine antifouling and anti-biocorrosion aspects.
基金supported financially by the National Natural Science Foundation of China (Nos. 51501199, 51631009 and U1906226)the National Key Research and Development Program of China (No. 2016YFB0300205)。
文摘304 stainless steel(SS) used as orthodontic wire during orthodontics faces the risk of microbiologically influenced corrosion(MIC) due to diverse flora environment. Hereinto, Streptococcus mutans(S. mutans)is the most important cariogenic bacteria. In this work, MIC behavior of a new 304-Cu SS in presence of S. mutans was studied by the observations using scanning electron microscopy(SEM) and confocal laser scanning microscopy(CLSM) including live/dead staining, extracellular polymeric substance(EPS)staining and pitting corrosion, electrochemical test, and X-ray photoelectron spectroscopy(XPS). Above results showed that 304-Cu SS possessed excellent biofilm inhibition ability and presented lower corrosion current density(icorr), larger polarization resistance(Rp) and charge transfer resistance(Rct) in the presence of S. mutans, indicating that 304-Cu SS had a better MIC resistance against S. mutans. It was further affirmed by XPS results that the presence of Cu-oxide in passive film of 304-Cu SS inhibited the formation of biofilm.
基金supported by National Institute of Dental and Craniofacial Research Grant DE10362
文摘Alkali production by oral bacteria is believed to have a major impact on oral microbial ecology and to be inibitory to the initiation and progression of dental caries.A substantial body of evidence is beginning to accumulate that indicates the modulation of the alkalinogenic potential of dental biofilms may be a promising strategy for caries control.This brief review highlights recent progress toward understanding molecular genetic and physiologic aspects of important alkali-generating pathways in oral bacteria,and the role of alkali production in the ecology of dental biofilms in health and disease.
基金supported by the projects of Qujing Normal University (Nos.TD200901 and 2009ZD009)
文摘Corrosion inhibition of stainless steel due to a sulfate-reducing bacteria (SRB) biofilm in seawater was studied. By atomic force microscopy, a layer of fish-scale-like biofilm was found to form as stainless steel coupons were exposed to the culture media with SRB, and this biofilm grew more and more compact. As a result, coupons' surface under the biofilm turned irregular less slowly than that exposed to the sterilized culture media. Then, physicoelectric characteristics of the electrode/biofilm/solution interface were investigated by electrochemical impedance spectroscopy (EIS), and the coverage of the biofilm as well as the relative irregularity of coupons' surface was also recorded by EIS spectra. Finally, anodic cyclic polarization results further demonstrated the protective property of the biofilm. Therefore, in estimation of SRB-implicated corrosion of stainless steel, not only the detrimental SRB metabolites but also the protective SRB biofilm as well should be taken into account.
基金Supported by Tianjin Natural Science Foundation Project(07JCYBJC16000)Key Technologies Integration and Students' Comprehensive Ability Improvement Project of Animal Hospital Affiliated to Tianjin Agricultural University(ZH004901)
文摘Pig Actinobacillus pleuropneumoniae(App) could induce chronic respiratory tract infection in pigs, which causes major economic losses on pig industry. Bacterial biofilm(BBF) is bacterial community adsorbed on the surface of biomaterials or body cavity, to protect bacteria escape, and recurrent outbreaks of related infectious diseases and chronic infections resulting therefrom are called bacterial biofilm diseases. App BF belongs to polymers with spatial structure in vitro, and its formation is regulated by multiple genes. Among them, gene deletion of the key component TolC of multidrug efflux pumps and type I secretion systems causes that App BF adhesion weakens; gene deletion of catalytic core ClpP of Clp proteolytic complex induces the inhibition of BF formation; outer membrane lipoprotein VacJ of App promotes BF formation; gene deletion of active enzyme LuxS enhances the formation of App BF and decreases bacterial adhesion ability; gene deletion of Adh obviously declines bacterial accumulation, BF formation and adhesion to host cells. In this paper, BF formation or inhibition mechanism in App is elaborated from molecular level, which could provide reference basis for exploring the prevention of its biofilm diseases.
基金National Key R&D Program of China(2022YFA1103200,2017YFA0106400,2021YFA1100900)Ministry of Science and Technology of China(2020YFC2002804)+3 种基金National Natural Science Foundation of China(91749124,81772389,82070108)Major Program of Development Fund for Shanghai Zhangjiang National Innovation Demonstration Zone(ZJ2018-ZD-004)Fundamental Research Funds for the Central Universities(22120190149 and kx0200020173386)Peak Disciplines(Type IV)of Institutions of Higher Learning in Shanghai。
文摘Fibroblast activation protein(Fap)is a serine protease that degrades denatured type I collagen,α2-antiplasmin and FGF21.Fap is highly expressed in bone marrow stromal cells and functions as an osteogenic suppressor and can be inhibited by the bone growth factor Osteolectin(Oln).Fap is also expressed in synovial fibroblasts and positively correlated with the severity of rheumatoid arthritis(RA).However,whether Fap plays a critical role in osteoarthritis(OA)remains poorly understood.Here,we found that Fap is significantly elevated in osteoarthritic synovium,while the genetic deletion or pharmacological inhibition of Fap significantly ameliorated posttraumatic OA in mice.Mechanistically,we found that Fap degrades denatured type II collagen(Col II)and Mmp13-cleaved native Col II.Intra-articular injection of r Fap significantly accelerated Col II degradation and OA progression.In contrast,Oln is expressed in the superficial layer of articular cartilage and is significantly downregulated in OA.Genetic deletion of Oln significantly exacerbated OA progression,which was partially rescued by Fap deletion or inhibition.Intra-articular injection of r Oln significantly ameliorated OA progression.Taken together,these findings identify Fap as a critical pathogenic factor in OA that could be targeted by both synthetic and endogenous inhibitors to ameliorate articular cartilage degradation.
文摘Biofilms act as a reservoir of infection, and periodically release cells in vicinity that are capable of developing new biofilm colonies and disseminate infection. Many chronic bacterial infections are serious that are associated with biofilms and have high morbidity and mortality, partly due to their higher resistance to antimicrobial agents, and partly due to lack of strong biocides which can efficiently treat and inhibit biofilm formation. We recently demonstrated that nonequilibrium non-thermal dielectric-barrier discharge plasma (Plasma) can also be applied to control pathogens via applying treated-liquids, and these liquids acquire broad-spectrum antimicrobial properties. In present studies we demonstrated a range of plasma-activated simple chemical solutions which significantly inhibited biofilm formation by multidrug-resistant bacterial pathogens. Plasma-activated methionine solution exhibited strong inhibitory activity against the biofilms of car-bapenem-resistant Acinetobacter baumannii, methicillin-resistant Staphylococcus aureus, metal-lo-β-lactamase (NDM1)-positive Klebsiella pneumoniae, and Enterococcus faecalis, and prevented the formation of biofilms by about 70% as compared to untreated controls in single exposure. In addition to inhibition of biofilm formation, a complete inactivation of biofilm-embedded bacterial cells was observed in less than 30 minute’s exposure to candidate plasma-activated methionine solution. These findings suggest that plasma-activated solutions have a potential to prevent biofilm formation, and as biofilm inhibitor.
基金This work was supported by Shenzhen-Hong Kong Science and Technology Innovation Cooperation Zone Shenzhen Park Project:HZQB-KCZYB-2020030the National Natural Science Foundation of China(No.91860131and No.52074157)+2 种基金Guangdong Provincial Department of Science and Technology,Key-Area Research and Development Program of Guangdong Province(No.2020B090923002)the National Key Research and Development Program of China(No.2017YFB0702901)the Shenzhen Science and Technology Innovation Commission(No.JCYJ20170817111811303,No.KQTD20170328154443162and No.ZDSYS201703031748354).
文摘The additive manufacturing(AM)of Ni-based superalloys has attracted extensive interest from both academia and industry due to its unique capabilities to fabricate complex and high-performance components for use in high-end industrial systems.However,the intense temperature gradient induced by the rapid heating and cooling processes of AM can generate high levels of residual stress and metastable chemical and structural states,inevitably leading to severe metallurgical defects in Ni-based superalloys.Cracks are the greatest threat to these materials’integrity as they can rapidly propagate and thereby cause sudden and non-predictable failure.Consequently,there is a need for a deeper understanding of residual stress and cracking mechanisms in additively manufactured Ni-based superalloys and ways to potentially prevent cracking,as this knowledge will enable the wider application of these unique materials.To this end,this paper comprehensively reviews the residual stress and the various mechanisms of crack formation in Ni-based superalloys during AM.In addition,several common methods for inhibiting crack formation are presented to assist the research community to develop methods for the fabrication of crack-free additively manufactured components.
文摘Objective:To characterize biofilm production by clinical(n=21)and environmental(n=11)isolates of Burkholderia pseudomallei and evaluate the production of proteases,hemolysins and siderophores.Methods:Initially,the 32 strains were evaluated for biofilm production in Müller-Hinton broth-1%glucose(MH-1%glucose)and BHI broth-1%glucose,using the crystal violet staining technique.Subsequently,growing(48 h)and mature(72 h)biofilms were evaluated by confocal microscopy.Finally,the production of proteases,hemolysins and siderophores by planktonic aggregates,growing biofilms and mature biofilms was evaluated.Results:All isolates produced biofilms,but clinical isolates had significantly higher biomass in both MH-1%glucose(P<0.001)and BHI-glucose 1%(P=0.005).The structural analyses by confocal microscopy showed thick biofilms,composed of multiple layers of cells,homogeneously arranged,with mature biofilms of clinical isolates presenting higher biomass(P=0.019)and thickness of the entire area(P=0.029),and lower roughness coefficient(P=0.007)than those of environmental isolates.Protease production by growing biofilms was significantly greater than that of planktonic(P<0.001)and mature biofilms(P<0.001).Hemolysin release by planktonic aggregates was higher than that of biofilms(P<0.001).Regarding siderophores,mature biofilms presented higher production than growing biofilms(P<0.001)and planktonic aggregates(P<0.001).Conclusions:Clinical isolates have higher production of biofilms than their environmental counterparts;protease and siderophores seem important for growth and maintenance of Burkholderia pseudomallei biofilms.
基金funded by grants from the National Natural Science Foundation of China (31872911)the National Key Research Program of China (2018YFC1603800)。
文摘Salmonella and their biofilm formation are the primary bacterial causes of foodborne outbreaks and crosscontamination. The objective of the study was to investigate the potential of Salmonella phages as an alternative technology for biofilm removal. In this work, 21 Salmonella phages were isolated from a chicken farm and slaughter plant and the phage(CW1)with the broadest spectrum was characterized. Complete genome sequence analysis revealed that the genomes of phage CW1 is composed of 41 763 bp with 58 open reading frames(ORFs)and a holin-endolysin system and it does not encode any virulence or lysogeny. A phage cocktail consisted of CW1(with the broadest spectrum of 70.49%)and CW11, M4 and M10(with a high lytic activity of more than 67.11%)was established. Treatment with the cocktail reduced the cells in the developing biofilm and mature biofilm by 0.79 lg(CFU/cm~2)and 0.4 lg(CFU/cm~2), respectively. More dead cells and scattered extracellular polymeric substances(EPS)were observed by confocal laser scanning microscopy and scanning electron microscopy. Raman analysis found that carbohydrates and proteins were the identification receptors for scattered EPS. This finding suggests that this phage cockta il has potential applications for the sterilization of Salmonella biofilm during meat processing.
文摘Objective: This study focused on the antibacterial and anti-proliferative activity of extracts from Carica papaya and Cocos nucifera roots. Methodology: The minimum inhibitory concentration and the minimum bactericidal concentration of the extracts on Escherichia coli, Pseudomonas aeruginosa, Streptococcus mutans, and Staphylococcus aureus were deduced by the microdilution method. The anti-biofilm activity was determined on all four strains and anti-quorum sensing activity by inhibition of violacein production in Chromobacterium violaceum. Anti-proliferative activity on prostate cultured cancer cells was evaluated by MTT assay. Sterols and triterpenes were also assayed in this study. Results: The methanolic extract of Carica papaya showed the best anti-biofilm effect with a percentage inhibition of 66.10 ± 1.79. The methanolic extract of Cocos nucifera had the strongest inhibition on the production of quorum sensing (61.42 ± 0.28). In addition, the methanolic extract of Cocos nucifera roots showed the best cytotoxic effect on prostate cancer LNCaP cell lines (IC<sub>50</sub> = 26.98 ± 2.6 μg/mL) and Carica papaya on the PC-3 lines (IC<sub>50</sub> = 127.20 ± 5.99 μg/mL). The extracts were also rich in triterpenes and sterols. Conclusion: This study provides support for the ethnomedical use of Carica papaya and Cocos nucifera roots as an antimicrobial and anticancer.
基金Supported by the National Natural Science Foundation of China(No.41867056)the Guizhou Provincial Key Technology R&D Program(Nos.2021470,2023216)。
文摘Denitrifying bacteria in epiphytic biofilms play a crucial role in nitrogen cycle in aquatic habitats.However,little is known about the connection between algae and denitrifying bacteria and their assembly processes in epiphytic biofilms.Epiphytic biofilms were collected from submerged macrophytes(Patamogeton lucens and Najas marina L.)in the Caohai Lake,Guizhou,SW China,from July to November 2020 to:(1)investigate the impact of abiotic and biotic variables on denitrifying bacterial communities;(2)investigate the temporal variation of the algae-denitrifying bacteria co-occurrence networks;and(3)determine the contribution of deterministic and stochastic processes to the formation of denitrifying bacterial communities.Abiotic and biotic factors influenced the variation in the denitrifying bacterial community,as shown in the Mantel test.The co-occurrence network analysis unveiled intricate interactions among algae to denitrifying bacteria.Denitrifying bacterial community co-occurrence network complexity(larger average degrees representing stronger network complexity)increased continuously from July to September and decreased in October before increasing in November.The co-occurrence network complexity of the algae and nirS-encoding denitrifying bacteria tended to increase from July to November.The co-occurrence network complexity of the algal and denitrifying bacterial communities was modified by ammonia nitrogen(NH_(4)^(+)-N)and total phosphorus(TP),pH,and water temperature(WT),according to the ordinary least-squares(OLS)model.The modified stochasticity ratio(MST)results reveal that deterministic selection dominated the assembly of denitrifying bacterial communities.The influence of environmental variables to denitrifying bacterial communities,as well as characteristics of algal-bacterial co-occurrence networks and the assembly process of denitrifying bacterial communities,were discovered in epiphytic biofilms in this study.The findings could aid in the appropriate understanding and use of epiphytic biofilms denitrification function,as well as the enhancement of water quality.
