In recent years probiotics have been considered as a potential substitution of antibiotics to control pathogens and treat infectious diseases in aquaculture.In the present study a strain of Lactobacillus pentosus,name...In recent years probiotics have been considered as a potential substitution of antibiotics to control pathogens and treat infectious diseases in aquaculture.In the present study a strain of Lactobacillus pentosus,named as L.pentosus SF-1,was isolated from waters in aquaculture.The species identification of this strain was conducted by 16S rRNA sequence,and the physiological and biochemical characteristics of this strain were assessed.Furthermore,the virulence,antibiotic sensitivity,cell surface characteristics and acid/base-resistance of L.pentosus SF-1 were determined to evaluate the probiotic potentials of this strain.Specifically,L.pentosus SF-1 is sensitive to most common antibiotics,and no hemolysin was generated from it,indicating the safety of this strain to hosts.In addition,L.pentosus SF-1 was able to tolerate the artificial gastric juice at pH 3 for 4 h and the artificial intestinal fluid at pH 6.8 or 8.0 for 6 h.Moreover,the analysis of self-aggregation and the adhesion of L.pentosus SF-1 to organic solvents suggested a high potential of L.pentosus SF-1 to inhabit the hosts,which was confirmed by testing the colonization of L.pentosus SF-1 in germ-free zebrafish.Interestingly,L.pentosus SF-1 displayed a high bactericidal activity against several bacterial pathogens.Consistently,the incubation of L.pentosus SF-1 significantly promoted the expression of antimicrobial components in zebrafish,contributing to the protection of the fish from E.tarda infection in vivo.Taken together,the probiotic strain L.pentosus SF-1 could be applied as anti-infection reagent in aquaculture.展开更多
Plasma-activated water(PAW),as an extended form of cold atmospheric-pressure plasma,greatly expands the application of plasma-based technology.The biological effects of PAW are closely related to the aqueous reactive ...Plasma-activated water(PAW),as an extended form of cold atmospheric-pressure plasma,greatly expands the application of plasma-based technology.The biological effects of PAW are closely related to the aqueous reactive species,which can be regulated by the activation process.In this study,surface plasma-activated air(SAA)and a He+O_(2)plasma jet(Jet)were parallelly combined(the SAA+Jet combination)or sequentially combined(the SAA→Jet combination and the Jet→SAA combination)to prepare plasma-activated saline(PAS).The PAS activated by the combinations exhibited stronger bactericidal effects than that activated by the SAA or the Jet alone.The concentrations of H_(2)O_(2)and NO_(2)^(-)were higher in the PAS activated by the Jet→SAA combination,while ONOO^(-)concentrations were close in the three kinds of PAS and^(1)O_(2)concentrations were higher in the PAS activated by the SAA+Jet combination.The analysis of scavengers also demonstrated that H_(2)O_(2),^(1)O_(2),and ONOO^(-)in the PAS activated by the SAA+Jet combination,and^(1)O_(2)in the PAS activated by the Jet→SAA combination played critical roles in bactericidal effects.Further,the effective placement time of the three PAS varied,and the PAS activated by the Jet→SAA combination could also inactivate 2.6-log_(10)of MRSA cells after placement for more than 60 min.The regulation of reactive species in plasma-activated water via different combinations of plasma devices could improve the directional application of plasma-activated water in the biomedical field.展开更多
Introduction: The aim of this study was to improve the DISTER-UV and to perform microbiological quality control at the biomedical laboratory of the West African Polytechnic University from January 2022 to November 202...Introduction: The aim of this study was to improve the DISTER-UV and to perform microbiological quality control at the biomedical laboratory of the West African Polytechnic University from January 2022 to November 2022. Methodology: During this eleven-month prospective study, we set up a quality control device (QCD). For microbiological quality control, we performed different cultures of bacteria with different bacteriological and morphological characteristics at T0 (no sterilization) and at T30 (after 30 minutes of sterilization under DISTER-UV). Results: After the realization, the DCQ attached to the DISTER-UV1 allows to display of the UV wavelength present in the light box. This device also displays and alerts when the UV intensity emitted by the lamps is below 250 nm. During microbiological quality control, the cultures carried out at T30 and incubated for 24 hours did not reveal any bacterial colonies. This shows the bactericidal character of DISTER-UV-2. Conclusion: The improvement and the microbiological quality control allowed us to switch from DISTER-UV1 (without sensor) to DISTER-UV-2 (with sensor or DCQ). The biological control allowed us to affirm that the DISTER-UV-2 is bactericidal.展开更多
This study aimed to explore the anti-bacterial and anti-fungal activities of extracts from different parts of plants in the Zingiberaceae family.The inhibitory rate,minimum inhibitory concentration(MIC),and minimum ba...This study aimed to explore the anti-bacterial and anti-fungal activities of extracts from different parts of plants in the Zingiberaceae family.The inhibitory rate,minimum inhibitory concentration(MIC),and minimum bactericidal concentration(MBC)of leaf and stem,and root and rhizome extracts from Alpinia katsumadai Hayata,Alpinia oxyphylla Miq×Alpinia henryi K.Schumann,Alpinia oblongifolia Hayata,Alpinia nigra(Gaertn.)Burtt,Amomum villosum Lour,Alpinia zerumbet(Pers.)Burtt.et Smith and Alpinia oxyphylla Miq were determined using the fungus cake method and double dilution method.The seven Zingiberaceae plants exhibited characteristic antibacterial activities against pathogenic bacteria and fungi.At a 1.5 mg mL^(−1),A.zerumbet root and rhizome extracts exhibited strong inhibitory activity against S.aureus and E.coli,with 83.23%and 79.62%,respectively.In addition,A.zerumbet leaf and stem extracts had an inhibitory rate of 90.85%against P.aeruginosa.At the same concentration,the leaf and stem,root and rhizome extracts of A.katsumadai had the best anti-bacterial effect against F.oxysporum,with inhibition rates of 84.46%and 84.73%,respectively.Moreover,A.katsumadai and A.zerumbet leaf and stem extracts had the most significant antibacterial effect against S.aureus,with a MIC of 0.063 mg mL^(−1).Thus,both A.katsumadai and A.zerumbet extracts had significant antibacterial activity.In addition,by comparing the inhibitory effect of extracts from different parts,it was found that the inhibitory rate and average inhibitory rate of extracts from leaf and stem were higher than those from root and rhizome.The chemical constituents of A.katsumadai and A.zerumbet,determined by the high-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS),revealed that citric acid(CA),alpinetin,and pinocembrin(PNCB)were the functional constituents yielding the antibacterial activity.Overall,A.katsumadai and A.zerumbet have the potential to be developed as new plant fungicides and bactericides.展开更多
The determination of 7 bactericidals residues,including chlorthalonil,dichlofluanid,tolylfluanid,captan,folpet,captafol and deltamethrin,in foods by using on-line gel permeation chromatography(GPC) coupled with gas ch...The determination of 7 bactericidals residues,including chlorthalonil,dichlofluanid,tolylfluanid,captan,folpet,captafol and deltamethrin,in foods by using on-line gel permeation chromatography(GPC) coupled with gas chromatography-mass spectrometry(GC-MS).Bactericidal residues were extracted with acetonitrile,and cleaned up by ENVI-Crab,LC-NH2 column and GPC,respectively.The analysis of 7 bactericidals residues was performed by GC-MS.The average recoveries of analytes were range of 75%-120% with RSD of 3.5%-10.3%.展开更多
The application of cutting fluid in the field of engineering manufacturing has a history of hundreds of years,and it plays a vital role in the processing efficiency and surface quality of parts.Among them,water-based ...The application of cutting fluid in the field of engineering manufacturing has a history of hundreds of years,and it plays a vital role in the processing efficiency and surface quality of parts.Among them,water-based cutting fluid accounts for more than 90%of the consumption of cutting fluid.However,long-term recycling of water-based cutting fluid could easily cause deterioration,and the breeding of bacteria could cause the cutting fluid to fail,increase manufacturing costs,and even endanger the health of workers.Traditional bactericides could improve the biological stability of cutting fluids,but they are toxic to the environment and do not conform to the development trend of low-carbon manufacturing.Low-carbon manufacturing is inevitable and the direction of sustainable manufacturing.The use of nanomaterials,transition metal complexes,and physical sterilization methods on the bacterial cell membrane and genetic material could effectively solve this problem.In this article,the mechanism of action of additives and microbial metabolites was first analyzed.Then,the denaturation mechanism of traditional bactericides on the target protein and the effect of sterilization efficiency were summarized.Further,the mechanism of nanomaterials disrupting cell membrane potential was discussed.The effects of lipophilicity and the atomic number of transition metal complexes on cell membrane penetration were also summarized,and the effects of ultraviolet rays and ozone on the destruction of bacterial genetic material were reviewed.In other words,the bactericidal performance,hazard,degradability,and economics of various sterilization methods were comprehensively evaluated,and the potential development direction of improving the biological stability of cutting fluid was proposed.展开更多
ByBimolecular Nucleophilic Substitution, four new types of alkylene triphenyl double quaternary phosphonium salt were synthesized respectively by using triphenylphosphine, 1,3-dibromopropane, 1,6-dibromohexane,1,10-di...ByBimolecular Nucleophilic Substitution, four new types of alkylene triphenyl double quaternary phosphonium salt were synthesized respectively by using triphenylphosphine, 1,3-dibromopropane, 1,6-dibromohexane,1,10-dibromo- decane, 1,12-dibromododecane as raw materials and using DMAC as the solvent, under a certain temperature and reac- tion time. The productivity is 58% - 83%. The molecular structures of the products were characterized by IR, NMR and elemental analysis. The sterilizing effect of 1,6-hexylidene triphenyl double phosphonium bromide(HTDPB) and 1,12- dodecylidene triphenyl double phosphonium bromide(DoTDPB) was evaluated by using extinct dilution method.The experimental result shows that the sterilizing effect of DoTDPB is better than the effect of HTDPB under the same drug concentration and contact time. When the concentration of DoTDPB was 20 mg/L and the contact time was 0.5 h, the sterilizing rate of DoTDPB used to kill saprophytic bacteria (TGB), sulfate-reducing bacteria (SRB) and iron bacteria (IB) was 95.56%, 84% and 99.58% respectively.展开更多
Quaternary ammonium compound are a class of broad-spectrum,high-efficiency and low-toxicity bactericide,which are widely used in daily life and industrial sterilization.Herein,the current state of domestic quaternary ...Quaternary ammonium compound are a class of broad-spectrum,high-efficiency and low-toxicity bactericide,which are widely used in daily life and industrial sterilization.Herein,the current state of domestic quaternary ammonium disinfectant products was summarized,as well as those new products developed and studied,and the development trend was also predicted.展开更多
The iron compounds in the oxidation state (VI) have the specific advantage of being powerful oxidants and bactericides. This feature explains their particular interest in the treatment of water. The aim of this work i...The iron compounds in the oxidation state (VI) have the specific advantage of being powerful oxidants and bactericides. This feature explains their particular interest in the treatment of water. The aim of this work is to prepare Na2FeO4 stable at ambient in order to optimize the key parameters influencing the performance of the oxidation of iron (II) to iron (VI), as well as to monitor its degradation over time. The synthesis of this phase has been carried out by using the dry reaction Na2O2 with Fe2O3 with a temperature of 700°C for a reaction time of 13 hours with a Na/Fe ratio of 4 to make it possible to simplify the synthesis procedure, to minimize the cost and enhance the production of iron (VI) to meet the growing demand of ferrate (VI) for its interest in water treatment. The obtained phase was characterized by UV spectrophotometer by measuring the optical density at a wavelength of 507 nm.展开更多
Essential oils (EOs) are natural bioactive compounds with antibacterial activity against a variety of microorganisms including phytopathogens. The use of EOs and their components as viable therapeutic antibacterials i...Essential oils (EOs) are natural bioactive compounds with antibacterial activity against a variety of microorganisms including phytopathogens. The use of EOs and their components as viable therapeutic antibacterials is however greatly compromised by their volatile nature, hydrophobicity and instability when exposed to environmental and physiological factors. Encapsulation of these compounds in an appropriate carrier system can alleviate these challenges. This study therefore aimed at developing, characterizing and evaluating the efficacy of antibacterial potential of thymol and eugenol loaded chitosan nanoparticles (TCNPs and ECNPs) against <i>Ralstonia solanacearum</i>, the bacterial wilt-causing pathogen in potatoes. Synthesis of TCNP and ECNP was achieved via ionic gelation method and the prepared nanoparticles characterized by their particle size distributions, encapsulation efficiency, loading capacity (LC) and <i>in-vitro</i> release characteristics. Antibacterial activities of the nanoparticles were investigated using agar dilution and colony counting methods and their minimum inhibitory concentration (MIC) determined by 96-well broth micro-dilution method. Scanning electron microscope images of TCNPs and ECNPs showed that the nanoparticles were spherical in shape and were well separated with an average particle size of 590 nm and 555 nm respectively. The average size of chitosan nanoparticles alone was however 375 nm. The encapsulation efficiency was 72.9% for TCNP (with 48.3% LC) and 71.7% for ECNP (with 49.5% LC). The release of thymol and eugenol from the microcapsules was found to be pH dependent with the highest release at pH 1.5. The growth inhibition of <i>R. solanacearum</i> was 92% and 94% for TCNP and ECNPs respectively. The MIC of thymol and eugenol before encapsulation was 175 μg/ml and 275 μg/ml respectively, but this reduced significantly to 22.5 μg/ml and 45 μg/ml after encapsulation. Thus, encapsulation of thymol and eugenol in chitosan nanoparticles has shown promising potential as a bactericide alternative for <i>R. solanacearum</i> and could be useful in managing the soil borne phytopathogen.展开更多
This work is a result of previously done studies on the synthesis of A2FeVIO4 wet ferrate (VI) formula, using chlorine as an oxidant. The major problem of these ferrates is related to their stability over time. This b...This work is a result of previously done studies on the synthesis of A2FeVIO4 wet ferrate (VI) formula, using chlorine as an oxidant. The major problem of these ferrates is related to their stability over time. This brings us to identify and optimize the critical parameters influencing the preparation of the Na2FeO4 at room stable phase with acceptable performance. The use of water bleach (hypochlorite ClO‾) at a chlorometric degree of 50°F in the synthesis of the Na2FeO4 ambient stable phase promotes the oxidation of iron (II) iron to (VI) in a concentrated NaOH alkaline medium. The synthesis reaction is in the presence of FeSO4 7H2O hydrated iron sulfate at a temperature of about 55°C in order to simplify the synthesis process, to enhance the production of the Fe (VI) and to meet the growing demand of ferrates (VI) for their interest in the treatment of water. Monitoring the degradation of synthesized Na2FeO4 shows its stability up to 12 months, which facilitates storage and transportation. The phases obtained were characterized by IR spectroscopy, and RX by UV spectrophotometer, measuring the optical density at 507 nm.展开更多
Objective:To ascertain the potential antibacterial activity of honey against clinical isolates of Escherichia coli(E.coli),Pseudomonas aeruginosa(P.aeruginosa) and Salmonella enterica serovar Typhi(S.enterica serovar ...Objective:To ascertain the potential antibacterial activity of honey against clinical isolates of Escherichia coli(E.coli),Pseudomonas aeruginosa(P.aeruginosa) and Salmonella enterica serovar Typhi(S.enterica serovar Typhi) by in vitro methods.Methods:The partial inhibitory concentration(PIC),minimum inhibitory concentration(MIC) and minimum bactericidal concentration(MBC) values of the autoclaved honey(extracted from Apis indica hive by indigenous method) were determined for S.enterica serovar Typhi(n=8:from blood cultute), E.coli(n=5:from urine culture) and P.aeruginosa(n=5:from pus culture) isolates by in vitro methods.Results:The PICs of the honey tested for the isolates ranged 0.50%-1.25%(v/v) for S. enterica serovar Typhi,0.75%-1.50%(v/v) for E.coli and 1.00%-1.25%(v/v) for P.aeruginosa, while the MICs ranged 1.75%-3.00%(v/v),3.00%-3.50%(v/v) and 3.50%(v/v),respectively.The P.aeruginosa and E.coli isolates had MBC value of 4.00%(v/v):the S.enterica serovar Typhi showed MBCs in between 3.00%and 3.50%(v/v).The bactericidal activity of honey was achieved at concentration 3.00%(v/v) for S.enterica serovar Typhi and E.coli,and at 3.50%(v/v) for P. aeruginosa.Conclusions:The excellent antibacterial activity of honey against clinical bacterial isolates indicates the usefulness of honey in clinical practice against bacterial infection.展开更多
Objective:To investigate the synergic antibacterial activity of garlic and tazma honey against standard and clinical pathogenic bacteria.Methods:Antimicrobial activity of tazma honey,garlic and mixture of them against...Objective:To investigate the synergic antibacterial activity of garlic and tazma honey against standard and clinical pathogenic bacteria.Methods:Antimicrobial activity of tazma honey,garlic and mixture of them against pathogenic bacteria were determined.Chloramphenicol and water were used as positive and negative controls,respectively.Minimum inhibitory concentration(MIC)and minimum bactericidal concentration of antimicrobial samples were determined using standard methods.Results:Inhibition zone of mixture of garlic and tazma honey against all tested pathogens was significantly(P≤0.05)greater than garlic and tazma honey alone.The diameter zone of inhibition ranged from(18±1)to(35±1)mm for mixture of garlic and tazma honey,(12±1)to(20±1)nun for tazma honey and(14±1)to(22±1)mm for garlic as compared with(10±1)to(30±1)mm for chloramphenicol.The combination of garlic and tazma honey(30-35 mm)was more significantly(P≤0.05)effective against Salmonella(NCTC 8385),Staphylococcus aureus(ATCC 25923),Lyesria moncytogenes(ATCC 19116)and Streptococcus pneumonia(ATCC 63).Results also showed considerable antimicrobial activity of garlic and tazma honey.MIC of mixture of garlic and tazma honey at 6.25%against total test bacteria was 88.9%.MIC of mixture of garlic and tazma honey at6.25%against Gram positive and negative were 100%and 83.33%,respectively.The bactericidal activities of garlic,tazma honey,and mixture of garlic and tazma honey against all pathogenic bacteria at 6.25%concentration were 66.6%,55.6%and 55.6%,respectively.Conclusions:This finding strongly supports the claim of the local community to use the combination of tazma honey and garlic for the treatment of different pathogenic bacterial infections.Therefore,garlic in combination with tazma honey can serve as an alternative natural antimicrobial drug for the treatment of pathogenic bacterial infections.Further in vivo study is recommended to come up with a comprehensive conclusion.展开更多
AIM: To investigate the bactericidal effects of Chenopodium ambrosioides L.(CAL) against Helicobacter pylori(H.pylori) both in vitro and in vivo.METHODS: For in vitro experiments, the inhibitory activity of CAL was te...AIM: To investigate the bactericidal effects of Chenopodium ambrosioides L.(CAL) against Helicobacter pylori(H.pylori) both in vitro and in vivo.METHODS: For in vitro experiments, the inhibitory activity of CAL was tested using an agar dilution method; H.pylori strain NCTC11637 was incubated on Columbia blood agar plates containing serial concentrations of CAL.The minimal inhibitory concentration(MIC) was determined by the absence of H.pylori colonies on the agar plate.Time-kill curves were used to evaluate bactericidal activity; the average number of colonies was calculated at 0, 2, 8 and 24 h after liquid incubation with concentrations of CAL at 0.5, 1, and 2 × MIC.For in vivo experiments, H.pylori-infected mice were randomly divided into CAL, triple therapy(lansoprazole, metronidazole, and clarithromycin), blank control, or H.pylori control groups.The eradication ratios were determined by positive findings from rapid urease tests(RUTs) and by histopathology.RESULTS: In vitro, the MIC of CAL against H.pylori was 16 mg/L.The time-kill curves showed a stable and persistent decreasing tendency with increasing CAL concentration, and the intensity of the bactericidal effect was proportional to dose; the 1 and 2 × MIC completely inhibited the growth of H.pylori at 24 h.In vivo, the eradication ratios in the CAL group were60%(6/10) by RUT and 50%(5/10) by histopathology.Ratios in the triple therapy group were both 70%(7/10), and there was no difference between the CAL and triple therapy groups.Histopathologic evaluation revealed massive bacterial colonization on the surface of gastric mucosa and slight infiltration of mononuclear cells after inoculation with H.pylori, but no obvious inflammation or other pathologic changes in gastric mucosa of mice from CAL and triple therapy groups.CONCLUSION: CAL demonstrates effective bactericidal activity against H.pylori both in vitro and in vivo.展开更多
Objective:To evaluate antibacterial activity of hot and cold ethanol and methanol leaf extracts of Ricinus communis L(R.communis)against Staphylococcus aureus(S.aureus)(NCTC 6571)and Escherichia coli(E.coli)(ATCC 2592...Objective:To evaluate antibacterial activity of hot and cold ethanol and methanol leaf extracts of Ricinus communis L(R.communis)against Staphylococcus aureus(S.aureus)(NCTC 6571)and Escherichia coli(E.coli)(ATCC 25922).Methods:Leaf powder of R.communis L.was extracted with hot(in Soxhlet)and cold ethanol and methanol,separately.The antibacterial activity of the extracts was determined by agar well diffusion and macro broth dilution methods.The extracts were also subjected to phytochemical analysis.Results:All the four test extracts showed inhibition on both S.aureus and E.coli.Hot and cold ethanol extracts revealed significantly(P<0.05)higher inhibition on S.aureus than methanol extracts,and the hot ethanol extract had the lowest minimum inhibitory concentration(MIC)and minimum bactericidal concentration(MBC)values(5 mg/mL and 10 mg/mL,respectively).E.coli was highly inhibited by hot extracts of both ethanol and methanol with the MIC and MBC of 40 mg/mL and 80 mg/mL,respectively.Phytochemical analysis revealed the presence of saponins,cardiac glycosides,tannins,flavonoids and terpenoids in all test extracts.Conclusions:This study demonstrates that the hot and cold methanol and ethanol extracts are potential sources for control of S.aureus and E.coli.Especially,the hot and cold extracts of ethanol are more inhibitive against 5.aureus even at lower concentration.Further study is needed to identify the specific bioactive compounds,their mode of action and their nontoxic nature in vivo condition.展开更多
in order to verify whether the bactericidal capacity of polymorphonuclear neutrophils (PMNs)could be abolished by the bypass-activated complement,intracellular bactericidal activity (ICBA),superoxide ions (O2-) and sp...in order to verify whether the bactericidal capacity of polymorphonuclear neutrophils (PMNs)could be abolished by the bypass-activated complement,intracellular bactericidal activity (ICBA),superoxide ions (O2-) and specific granules (SGs) 3 were determine展开更多
Silver nanoparticles have mainly been studied for their antimicrobial potential against bacteria, but have also proven to be active against several types of viruses, even against pebrine as well. Methods: Petri dishes...Silver nanoparticles have mainly been studied for their antimicrobial potential against bacteria, but have also proven to be active against several types of viruses, even against pebrine as well. Methods: Petri dishes and transmission electronic microscope were applied to observe silver nanoparticles against bacteria strains and nuclear polyhedral viruses (NPV) and cytoplasmic polyhedral viruses (CPV). For biological test, 108 CFU/mL NPV with strong pathogenicity, and the NPV samples treated with 1:100 ratio of “Sumerian Silver” for 8 hrs were sprayed on the mulberry leaves, respectively, for silkworm rearing. Conclusion: Silver nanoparticle solution showed a strong bactericidal effect against both G+ and G﹣bacterial pathogenic strains from Bombyx mori and mulberry. Under transmission electronic microscope (TEM), Bacillus sp. Samples showed light particles in the cells when treated with silver nanoparticles, in contrast, untreated samples showed homogeneity contents. Further, NPV particles showed no significant differences between treated and untreated samples, but CPV showed strong effects that almost all CPV were collapsed. For biological test, “Sumerian Silver” treated NPV showed no diseased silkworm but nearly all silkworms were dead with no treatment. It seems like that silver nanoparticles were proved to be more effective against CPV than that of NPV. The significant differences between two antivirus or virucidal mechanism should be greatly aroused the scientific interest.展开更多
High level infant mortality rates and onset of drug resistance has led into the possible development of indigenous probiotics as alternative bacteriotherapy in the control of infantile bacterial diarrhoea.This study w...High level infant mortality rates and onset of drug resistance has led into the possible development of indigenous probiotics as alternative bacteriotherapy in the control of infantile bacterial diarrhoea.This study was to determine the in vitro inhibitory potential of four probiotic candidates obtained from Nigerian indigenous fermented foods and beverages and from faecal specimens of healthy infants on infantile Gram-positive diarrhogenic bacterial pathogens.Potential probiotic candidates,AAOOL4,L.reuteri AAOOCH1,L.plantarum AA0025NN and L.delbrueckii AAOOT20 were assayed for in vitro bactericidal effects on diarrhogenic bacterial test strains-Bacillus cereus 25S,B.cereus 32S,B.licheniformis 26S and B.licheniformis 39S.All the test strains inoculated into an industrial infant weaning food already seeded with the probiotic strains were significantly inhibited within 96 hours.L.acidophilus AAOOL4,L.reuteri AAOOCH1,L.plantarum AAOO25NN and L.delbrueckii AAOOT20 had in vitro bactericidal effects on bacteri isolates implicated in infantile diarrhoea,indicating the probiotic potential of the candidates.展开更多
In this paper,the influences of gas doping(O2,N2,Air)on the concentrations of reactive species and bactericidal effects induced by a He plasma jet are studied.Firstly,results show that gas doping causes an increase in...In this paper,the influences of gas doping(O2,N2,Air)on the concentrations of reactive species and bactericidal effects induced by a He plasma jet are studied.Firstly,results show that gas doping causes an increase in voltage and a decrease in current compared with the pure He discharge under the same discharge power,which might be attributed to the different chemical characteristics of O2 and N2 and verified by the changes in the gaseous reactive species shown in the optical emission spectroscopy(OES)and Fourier transform infrared(FTIR)spectroscopy.Secondly,the concentrations of aqueous reactive oxygen species(ROS)and reactive nitrogen species(RNS)are tightly related to the addition of O2 and N2 into the working gas.The concentrations of aqueous NO-2 and NO-3 significantly increase while the concentrations of aqueous ROS decrease with the admixture of N2.The addition of O2 has little effect on the concentrations of NO-2 and NO-3 and pH values;however,the addition of O2 increases the concentration of O-2 and deceases the concentrations of H2O2 and OH.Finally,the results of bactericidal experiments demonstrate that the inactivation efficiency of the four types of plasma jets is He+O2>He+Air>He>He+N2,which is in accordance with the changing trend of the concentration of aqueous O.-2 Simultaneously to the better understanding of the formation and removal mechanisms of reactive species in the plasma–liquid interaction,these results also prove the effectiveness of regulating the concentrations of aqueous reactive species and the bacteria inactivation effects by gas doping.展开更多
This study has been embarked upon due to increased resistance of bacteria to many already synthesized drugs and the high price of the orthodox medicines in the market, the antimicrobial effect of Psidium guajava leaf ...This study has been embarked upon due to increased resistance of bacteria to many already synthesized drugs and the high price of the orthodox medicines in the market, the antimicrobial effect of Psidium guajava leaf extracts against selected drug-resistant bacteria will help to reduce the overdependence on orthodox or synthetic drugs which greater population of the society cannot afford due to economic/financial restriction. Ethanolic and aqueous extracts of Psidium guajava were assayed for antibacterial activity using the agar dilution method in the determination of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The bioactive components of the extracts were determined using standard techniques and the inhibitory activities of the extracts were compared to gentamicin, ciprofloxacin, erythromycin, azithromycin, ofloxacin, and nitrofurantoin. The MIC of the extract on the test organisms ranges from 10 mg/ml - 40 mg/ml. The sensitivity test showed that the organisms were susceptible to Psidium guajava leave extract except Pseudomonas aeruginosa. The phytochemical analysis of the extracts revealed the presence of bioactive compounds such as Tannin, Saponin, Balsam, Flavonoids, Alkaloids, Cardiac glycosides, Carbohydrate, Resins, Terpenes, and Sterols. It has been shown that the leaves of Psidium guajava have antibacterial effects and hence can be used to treat the ailments caused by those organisms at a particular dosage and concentration. However, more research work on its toxicity level, synergistic or antagonistic interaction with other plants or drugs is needed to consolidate its usage.展开更多
基金supported by the National Natural Science Foundation of China(No.31972802)the Natural Science Foundation of Shandong Province(No.ZR2019MC041)the Taishan Scholar Program of Shandong Province(No.tsqn201812023).
文摘In recent years probiotics have been considered as a potential substitution of antibiotics to control pathogens and treat infectious diseases in aquaculture.In the present study a strain of Lactobacillus pentosus,named as L.pentosus SF-1,was isolated from waters in aquaculture.The species identification of this strain was conducted by 16S rRNA sequence,and the physiological and biochemical characteristics of this strain were assessed.Furthermore,the virulence,antibiotic sensitivity,cell surface characteristics and acid/base-resistance of L.pentosus SF-1 were determined to evaluate the probiotic potentials of this strain.Specifically,L.pentosus SF-1 is sensitive to most common antibiotics,and no hemolysin was generated from it,indicating the safety of this strain to hosts.In addition,L.pentosus SF-1 was able to tolerate the artificial gastric juice at pH 3 for 4 h and the artificial intestinal fluid at pH 6.8 or 8.0 for 6 h.Moreover,the analysis of self-aggregation and the adhesion of L.pentosus SF-1 to organic solvents suggested a high potential of L.pentosus SF-1 to inhabit the hosts,which was confirmed by testing the colonization of L.pentosus SF-1 in germ-free zebrafish.Interestingly,L.pentosus SF-1 displayed a high bactericidal activity against several bacterial pathogens.Consistently,the incubation of L.pentosus SF-1 significantly promoted the expression of antimicrobial components in zebrafish,contributing to the protection of the fish from E.tarda infection in vivo.Taken together,the probiotic strain L.pentosus SF-1 could be applied as anti-infection reagent in aquaculture.
基金supported by National Natural Science Foundation of China(No.51977174)。
文摘Plasma-activated water(PAW),as an extended form of cold atmospheric-pressure plasma,greatly expands the application of plasma-based technology.The biological effects of PAW are closely related to the aqueous reactive species,which can be regulated by the activation process.In this study,surface plasma-activated air(SAA)and a He+O_(2)plasma jet(Jet)were parallelly combined(the SAA+Jet combination)or sequentially combined(the SAA→Jet combination and the Jet→SAA combination)to prepare plasma-activated saline(PAS).The PAS activated by the combinations exhibited stronger bactericidal effects than that activated by the SAA or the Jet alone.The concentrations of H_(2)O_(2)and NO_(2)^(-)were higher in the PAS activated by the Jet→SAA combination,while ONOO^(-)concentrations were close in the three kinds of PAS and^(1)O_(2)concentrations were higher in the PAS activated by the SAA+Jet combination.The analysis of scavengers also demonstrated that H_(2)O_(2),^(1)O_(2),and ONOO^(-)in the PAS activated by the SAA+Jet combination,and^(1)O_(2)in the PAS activated by the Jet→SAA combination played critical roles in bactericidal effects.Further,the effective placement time of the three PAS varied,and the PAS activated by the Jet→SAA combination could also inactivate 2.6-log_(10)of MRSA cells after placement for more than 60 min.The regulation of reactive species in plasma-activated water via different combinations of plasma devices could improve the directional application of plasma-activated water in the biomedical field.
文摘Introduction: The aim of this study was to improve the DISTER-UV and to perform microbiological quality control at the biomedical laboratory of the West African Polytechnic University from January 2022 to November 2022. Methodology: During this eleven-month prospective study, we set up a quality control device (QCD). For microbiological quality control, we performed different cultures of bacteria with different bacteriological and morphological characteristics at T0 (no sterilization) and at T30 (after 30 minutes of sterilization under DISTER-UV). Results: After the realization, the DCQ attached to the DISTER-UV1 allows to display of the UV wavelength present in the light box. This device also displays and alerts when the UV intensity emitted by the lamps is below 250 nm. During microbiological quality control, the cultures carried out at T30 and incubated for 24 hours did not reveal any bacterial colonies. This shows the bactericidal character of DISTER-UV-2. Conclusion: The improvement and the microbiological quality control allowed us to switch from DISTER-UV1 (without sensor) to DISTER-UV-2 (with sensor or DCQ). The biological control allowed us to affirm that the DISTER-UV-2 is bactericidal.
基金funded by the Forestry Science and Technology Innovation Project of Guangdong Province,China(2020KJCX010).
文摘This study aimed to explore the anti-bacterial and anti-fungal activities of extracts from different parts of plants in the Zingiberaceae family.The inhibitory rate,minimum inhibitory concentration(MIC),and minimum bactericidal concentration(MBC)of leaf and stem,and root and rhizome extracts from Alpinia katsumadai Hayata,Alpinia oxyphylla Miq×Alpinia henryi K.Schumann,Alpinia oblongifolia Hayata,Alpinia nigra(Gaertn.)Burtt,Amomum villosum Lour,Alpinia zerumbet(Pers.)Burtt.et Smith and Alpinia oxyphylla Miq were determined using the fungus cake method and double dilution method.The seven Zingiberaceae plants exhibited characteristic antibacterial activities against pathogenic bacteria and fungi.At a 1.5 mg mL^(−1),A.zerumbet root and rhizome extracts exhibited strong inhibitory activity against S.aureus and E.coli,with 83.23%and 79.62%,respectively.In addition,A.zerumbet leaf and stem extracts had an inhibitory rate of 90.85%against P.aeruginosa.At the same concentration,the leaf and stem,root and rhizome extracts of A.katsumadai had the best anti-bacterial effect against F.oxysporum,with inhibition rates of 84.46%and 84.73%,respectively.Moreover,A.katsumadai and A.zerumbet leaf and stem extracts had the most significant antibacterial effect against S.aureus,with a MIC of 0.063 mg mL^(−1).Thus,both A.katsumadai and A.zerumbet extracts had significant antibacterial activity.In addition,by comparing the inhibitory effect of extracts from different parts,it was found that the inhibitory rate and average inhibitory rate of extracts from leaf and stem were higher than those from root and rhizome.The chemical constituents of A.katsumadai and A.zerumbet,determined by the high-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS),revealed that citric acid(CA),alpinetin,and pinocembrin(PNCB)were the functional constituents yielding the antibacterial activity.Overall,A.katsumadai and A.zerumbet have the potential to be developed as new plant fungicides and bactericides.
文摘The determination of 7 bactericidals residues,including chlorthalonil,dichlofluanid,tolylfluanid,captan,folpet,captafol and deltamethrin,in foods by using on-line gel permeation chromatography(GPC) coupled with gas chromatography-mass spectrometry(GC-MS).Bactericidal residues were extracted with acetonitrile,and cleaned up by ENVI-Crab,LC-NH2 column and GPC,respectively.The analysis of 7 bactericidals residues was performed by GC-MS.The average recoveries of analytes were range of 75%-120% with RSD of 3.5%-10.3%.
基金Supported by National Key Research and Development Program of China(Grant No.2020YFB2010500)National Natural Science Foundation of China(Grant Nos.51975305,51905289)+2 种基金Shandong Provincial Major Science and Technology Innovation Engineering Projects of China(Grant No.2019JZZY020111)Shandong Provincial Natural Science Foundation of China(Grant Nos.ZR2020KE027,ZR2020ME158,ZR2019PEE008)Applied Basic Research Youth Project of Qingdao Science and Technology Plan(Grant No.19-6-2-63-cg)。
文摘The application of cutting fluid in the field of engineering manufacturing has a history of hundreds of years,and it plays a vital role in the processing efficiency and surface quality of parts.Among them,water-based cutting fluid accounts for more than 90%of the consumption of cutting fluid.However,long-term recycling of water-based cutting fluid could easily cause deterioration,and the breeding of bacteria could cause the cutting fluid to fail,increase manufacturing costs,and even endanger the health of workers.Traditional bactericides could improve the biological stability of cutting fluids,but they are toxic to the environment and do not conform to the development trend of low-carbon manufacturing.Low-carbon manufacturing is inevitable and the direction of sustainable manufacturing.The use of nanomaterials,transition metal complexes,and physical sterilization methods on the bacterial cell membrane and genetic material could effectively solve this problem.In this article,the mechanism of action of additives and microbial metabolites was first analyzed.Then,the denaturation mechanism of traditional bactericides on the target protein and the effect of sterilization efficiency were summarized.Further,the mechanism of nanomaterials disrupting cell membrane potential was discussed.The effects of lipophilicity and the atomic number of transition metal complexes on cell membrane penetration were also summarized,and the effects of ultraviolet rays and ozone on the destruction of bacterial genetic material were reviewed.In other words,the bactericidal performance,hazard,degradability,and economics of various sterilization methods were comprehensively evaluated,and the potential development direction of improving the biological stability of cutting fluid was proposed.
文摘ByBimolecular Nucleophilic Substitution, four new types of alkylene triphenyl double quaternary phosphonium salt were synthesized respectively by using triphenylphosphine, 1,3-dibromopropane, 1,6-dibromohexane,1,10-dibromo- decane, 1,12-dibromododecane as raw materials and using DMAC as the solvent, under a certain temperature and reac- tion time. The productivity is 58% - 83%. The molecular structures of the products were characterized by IR, NMR and elemental analysis. The sterilizing effect of 1,6-hexylidene triphenyl double phosphonium bromide(HTDPB) and 1,12- dodecylidene triphenyl double phosphonium bromide(DoTDPB) was evaluated by using extinct dilution method.The experimental result shows that the sterilizing effect of DoTDPB is better than the effect of HTDPB under the same drug concentration and contact time. When the concentration of DoTDPB was 20 mg/L and the contact time was 0.5 h, the sterilizing rate of DoTDPB used to kill saprophytic bacteria (TGB), sulfate-reducing bacteria (SRB) and iron bacteria (IB) was 95.56%, 84% and 99.58% respectively.
文摘Quaternary ammonium compound are a class of broad-spectrum,high-efficiency and low-toxicity bactericide,which are widely used in daily life and industrial sterilization.Herein,the current state of domestic quaternary ammonium disinfectant products was summarized,as well as those new products developed and studied,and the development trend was also predicted.
文摘The iron compounds in the oxidation state (VI) have the specific advantage of being powerful oxidants and bactericides. This feature explains their particular interest in the treatment of water. The aim of this work is to prepare Na2FeO4 stable at ambient in order to optimize the key parameters influencing the performance of the oxidation of iron (II) to iron (VI), as well as to monitor its degradation over time. The synthesis of this phase has been carried out by using the dry reaction Na2O2 with Fe2O3 with a temperature of 700°C for a reaction time of 13 hours with a Na/Fe ratio of 4 to make it possible to simplify the synthesis procedure, to minimize the cost and enhance the production of iron (VI) to meet the growing demand of ferrate (VI) for its interest in water treatment. The obtained phase was characterized by UV spectrophotometer by measuring the optical density at a wavelength of 507 nm.
文摘Essential oils (EOs) are natural bioactive compounds with antibacterial activity against a variety of microorganisms including phytopathogens. The use of EOs and their components as viable therapeutic antibacterials is however greatly compromised by their volatile nature, hydrophobicity and instability when exposed to environmental and physiological factors. Encapsulation of these compounds in an appropriate carrier system can alleviate these challenges. This study therefore aimed at developing, characterizing and evaluating the efficacy of antibacterial potential of thymol and eugenol loaded chitosan nanoparticles (TCNPs and ECNPs) against <i>Ralstonia solanacearum</i>, the bacterial wilt-causing pathogen in potatoes. Synthesis of TCNP and ECNP was achieved via ionic gelation method and the prepared nanoparticles characterized by their particle size distributions, encapsulation efficiency, loading capacity (LC) and <i>in-vitro</i> release characteristics. Antibacterial activities of the nanoparticles were investigated using agar dilution and colony counting methods and their minimum inhibitory concentration (MIC) determined by 96-well broth micro-dilution method. Scanning electron microscope images of TCNPs and ECNPs showed that the nanoparticles were spherical in shape and were well separated with an average particle size of 590 nm and 555 nm respectively. The average size of chitosan nanoparticles alone was however 375 nm. The encapsulation efficiency was 72.9% for TCNP (with 48.3% LC) and 71.7% for ECNP (with 49.5% LC). The release of thymol and eugenol from the microcapsules was found to be pH dependent with the highest release at pH 1.5. The growth inhibition of <i>R. solanacearum</i> was 92% and 94% for TCNP and ECNPs respectively. The MIC of thymol and eugenol before encapsulation was 175 μg/ml and 275 μg/ml respectively, but this reduced significantly to 22.5 μg/ml and 45 μg/ml after encapsulation. Thus, encapsulation of thymol and eugenol in chitosan nanoparticles has shown promising potential as a bactericide alternative for <i>R. solanacearum</i> and could be useful in managing the soil borne phytopathogen.
文摘This work is a result of previously done studies on the synthesis of A2FeVIO4 wet ferrate (VI) formula, using chlorine as an oxidant. The major problem of these ferrates is related to their stability over time. This brings us to identify and optimize the critical parameters influencing the preparation of the Na2FeO4 at room stable phase with acceptable performance. The use of water bleach (hypochlorite ClO‾) at a chlorometric degree of 50°F in the synthesis of the Na2FeO4 ambient stable phase promotes the oxidation of iron (II) iron to (VI) in a concentrated NaOH alkaline medium. The synthesis reaction is in the presence of FeSO4 7H2O hydrated iron sulfate at a temperature of about 55°C in order to simplify the synthesis process, to enhance the production of the Fe (VI) and to meet the growing demand of ferrates (VI) for their interest in the treatment of water. Monitoring the degradation of synthesized Na2FeO4 shows its stability up to 12 months, which facilitates storage and transportation. The phases obtained were characterized by IR spectroscopy, and RX by UV spectrophotometer, measuring the optical density at 507 nm.
文摘Objective:To ascertain the potential antibacterial activity of honey against clinical isolates of Escherichia coli(E.coli),Pseudomonas aeruginosa(P.aeruginosa) and Salmonella enterica serovar Typhi(S.enterica serovar Typhi) by in vitro methods.Methods:The partial inhibitory concentration(PIC),minimum inhibitory concentration(MIC) and minimum bactericidal concentration(MBC) values of the autoclaved honey(extracted from Apis indica hive by indigenous method) were determined for S.enterica serovar Typhi(n=8:from blood cultute), E.coli(n=5:from urine culture) and P.aeruginosa(n=5:from pus culture) isolates by in vitro methods.Results:The PICs of the honey tested for the isolates ranged 0.50%-1.25%(v/v) for S. enterica serovar Typhi,0.75%-1.50%(v/v) for E.coli and 1.00%-1.25%(v/v) for P.aeruginosa, while the MICs ranged 1.75%-3.00%(v/v),3.00%-3.50%(v/v) and 3.50%(v/v),respectively.The P.aeruginosa and E.coli isolates had MBC value of 4.00%(v/v):the S.enterica serovar Typhi showed MBCs in between 3.00%and 3.50%(v/v).The bactericidal activity of honey was achieved at concentration 3.00%(v/v) for S.enterica serovar Typhi and E.coli,and at 3.50%(v/v) for P. aeruginosa.Conclusions:The excellent antibacterial activity of honey against clinical bacterial isolates indicates the usefulness of honey in clinical practice against bacterial infection.
基金Supported by University of Condar(UOG/Budget/no.6215),Condar,Ethiopia
文摘Objective:To investigate the synergic antibacterial activity of garlic and tazma honey against standard and clinical pathogenic bacteria.Methods:Antimicrobial activity of tazma honey,garlic and mixture of them against pathogenic bacteria were determined.Chloramphenicol and water were used as positive and negative controls,respectively.Minimum inhibitory concentration(MIC)and minimum bactericidal concentration of antimicrobial samples were determined using standard methods.Results:Inhibition zone of mixture of garlic and tazma honey against all tested pathogens was significantly(P≤0.05)greater than garlic and tazma honey alone.The diameter zone of inhibition ranged from(18±1)to(35±1)mm for mixture of garlic and tazma honey,(12±1)to(20±1)nun for tazma honey and(14±1)to(22±1)mm for garlic as compared with(10±1)to(30±1)mm for chloramphenicol.The combination of garlic and tazma honey(30-35 mm)was more significantly(P≤0.05)effective against Salmonella(NCTC 8385),Staphylococcus aureus(ATCC 25923),Lyesria moncytogenes(ATCC 19116)and Streptococcus pneumonia(ATCC 63).Results also showed considerable antimicrobial activity of garlic and tazma honey.MIC of mixture of garlic and tazma honey at 6.25%against total test bacteria was 88.9%.MIC of mixture of garlic and tazma honey at6.25%against Gram positive and negative were 100%and 83.33%,respectively.The bactericidal activities of garlic,tazma honey,and mixture of garlic and tazma honey against all pathogenic bacteria at 6.25%concentration were 66.6%,55.6%and 55.6%,respectively.Conclusions:This finding strongly supports the claim of the local community to use the combination of tazma honey and garlic for the treatment of different pathogenic bacterial infections.Therefore,garlic in combination with tazma honey can serve as an alternative natural antimicrobial drug for the treatment of pathogenic bacterial infections.Further in vivo study is recommended to come up with a comprehensive conclusion.
基金Supported by National Natural Science Foundation Project of China,No.81072952
文摘AIM: To investigate the bactericidal effects of Chenopodium ambrosioides L.(CAL) against Helicobacter pylori(H.pylori) both in vitro and in vivo.METHODS: For in vitro experiments, the inhibitory activity of CAL was tested using an agar dilution method; H.pylori strain NCTC11637 was incubated on Columbia blood agar plates containing serial concentrations of CAL.The minimal inhibitory concentration(MIC) was determined by the absence of H.pylori colonies on the agar plate.Time-kill curves were used to evaluate bactericidal activity; the average number of colonies was calculated at 0, 2, 8 and 24 h after liquid incubation with concentrations of CAL at 0.5, 1, and 2 × MIC.For in vivo experiments, H.pylori-infected mice were randomly divided into CAL, triple therapy(lansoprazole, metronidazole, and clarithromycin), blank control, or H.pylori control groups.The eradication ratios were determined by positive findings from rapid urease tests(RUTs) and by histopathology.RESULTS: In vitro, the MIC of CAL against H.pylori was 16 mg/L.The time-kill curves showed a stable and persistent decreasing tendency with increasing CAL concentration, and the intensity of the bactericidal effect was proportional to dose; the 1 and 2 × MIC completely inhibited the growth of H.pylori at 24 h.In vivo, the eradication ratios in the CAL group were60%(6/10) by RUT and 50%(5/10) by histopathology.Ratios in the triple therapy group were both 70%(7/10), and there was no difference between the CAL and triple therapy groups.Histopathologic evaluation revealed massive bacterial colonization on the surface of gastric mucosa and slight infiltration of mononuclear cells after inoculation with H.pylori, but no obvious inflammation or other pathologic changes in gastric mucosa of mice from CAL and triple therapy groups.CONCLUSION: CAL demonstrates effective bactericidal activity against H.pylori both in vitro and in vivo.
文摘Objective:To evaluate antibacterial activity of hot and cold ethanol and methanol leaf extracts of Ricinus communis L(R.communis)against Staphylococcus aureus(S.aureus)(NCTC 6571)and Escherichia coli(E.coli)(ATCC 25922).Methods:Leaf powder of R.communis L.was extracted with hot(in Soxhlet)and cold ethanol and methanol,separately.The antibacterial activity of the extracts was determined by agar well diffusion and macro broth dilution methods.The extracts were also subjected to phytochemical analysis.Results:All the four test extracts showed inhibition on both S.aureus and E.coli.Hot and cold ethanol extracts revealed significantly(P<0.05)higher inhibition on S.aureus than methanol extracts,and the hot ethanol extract had the lowest minimum inhibitory concentration(MIC)and minimum bactericidal concentration(MBC)values(5 mg/mL and 10 mg/mL,respectively).E.coli was highly inhibited by hot extracts of both ethanol and methanol with the MIC and MBC of 40 mg/mL and 80 mg/mL,respectively.Phytochemical analysis revealed the presence of saponins,cardiac glycosides,tannins,flavonoids and terpenoids in all test extracts.Conclusions:This study demonstrates that the hot and cold methanol and ethanol extracts are potential sources for control of S.aureus and E.coli.Especially,the hot and cold extracts of ethanol are more inhibitive against 5.aureus even at lower concentration.Further study is needed to identify the specific bioactive compounds,their mode of action and their nontoxic nature in vivo condition.
文摘in order to verify whether the bactericidal capacity of polymorphonuclear neutrophils (PMNs)could be abolished by the bypass-activated complement,intracellular bactericidal activity (ICBA),superoxide ions (O2-) and specific granules (SGs) 3 were determine
文摘Silver nanoparticles have mainly been studied for their antimicrobial potential against bacteria, but have also proven to be active against several types of viruses, even against pebrine as well. Methods: Petri dishes and transmission electronic microscope were applied to observe silver nanoparticles against bacteria strains and nuclear polyhedral viruses (NPV) and cytoplasmic polyhedral viruses (CPV). For biological test, 108 CFU/mL NPV with strong pathogenicity, and the NPV samples treated with 1:100 ratio of “Sumerian Silver” for 8 hrs were sprayed on the mulberry leaves, respectively, for silkworm rearing. Conclusion: Silver nanoparticle solution showed a strong bactericidal effect against both G+ and G﹣bacterial pathogenic strains from Bombyx mori and mulberry. Under transmission electronic microscope (TEM), Bacillus sp. Samples showed light particles in the cells when treated with silver nanoparticles, in contrast, untreated samples showed homogeneity contents. Further, NPV particles showed no significant differences between treated and untreated samples, but CPV showed strong effects that almost all CPV were collapsed. For biological test, “Sumerian Silver” treated NPV showed no diseased silkworm but nearly all silkworms were dead with no treatment. It seems like that silver nanoparticles were proved to be more effective against CPV than that of NPV. The significant differences between two antivirus or virucidal mechanism should be greatly aroused the scientific interest.
文摘High level infant mortality rates and onset of drug resistance has led into the possible development of indigenous probiotics as alternative bacteriotherapy in the control of infantile bacterial diarrhoea.This study was to determine the in vitro inhibitory potential of four probiotic candidates obtained from Nigerian indigenous fermented foods and beverages and from faecal specimens of healthy infants on infantile Gram-positive diarrhogenic bacterial pathogens.Potential probiotic candidates,AAOOL4,L.reuteri AAOOCH1,L.plantarum AA0025NN and L.delbrueckii AAOOT20 were assayed for in vitro bactericidal effects on diarrhogenic bacterial test strains-Bacillus cereus 25S,B.cereus 32S,B.licheniformis 26S and B.licheniformis 39S.All the test strains inoculated into an industrial infant weaning food already seeded with the probiotic strains were significantly inhibited within 96 hours.L.acidophilus AAOOL4,L.reuteri AAOOCH1,L.plantarum AAOO25NN and L.delbrueckii AAOOT20 had in vitro bactericidal effects on bacteri isolates implicated in infantile diarrhoea,indicating the probiotic potential of the candidates.
基金supported by National Natural Science Foundation of China (Grant Nos. 51722705 and 51837008)
文摘In this paper,the influences of gas doping(O2,N2,Air)on the concentrations of reactive species and bactericidal effects induced by a He plasma jet are studied.Firstly,results show that gas doping causes an increase in voltage and a decrease in current compared with the pure He discharge under the same discharge power,which might be attributed to the different chemical characteristics of O2 and N2 and verified by the changes in the gaseous reactive species shown in the optical emission spectroscopy(OES)and Fourier transform infrared(FTIR)spectroscopy.Secondly,the concentrations of aqueous reactive oxygen species(ROS)and reactive nitrogen species(RNS)are tightly related to the addition of O2 and N2 into the working gas.The concentrations of aqueous NO-2 and NO-3 significantly increase while the concentrations of aqueous ROS decrease with the admixture of N2.The addition of O2 has little effect on the concentrations of NO-2 and NO-3 and pH values;however,the addition of O2 increases the concentration of O-2 and deceases the concentrations of H2O2 and OH.Finally,the results of bactericidal experiments demonstrate that the inactivation efficiency of the four types of plasma jets is He+O2>He+Air>He>He+N2,which is in accordance with the changing trend of the concentration of aqueous O.-2 Simultaneously to the better understanding of the formation and removal mechanisms of reactive species in the plasma–liquid interaction,these results also prove the effectiveness of regulating the concentrations of aqueous reactive species and the bacteria inactivation effects by gas doping.
文摘This study has been embarked upon due to increased resistance of bacteria to many already synthesized drugs and the high price of the orthodox medicines in the market, the antimicrobial effect of Psidium guajava leaf extracts against selected drug-resistant bacteria will help to reduce the overdependence on orthodox or synthetic drugs which greater population of the society cannot afford due to economic/financial restriction. Ethanolic and aqueous extracts of Psidium guajava were assayed for antibacterial activity using the agar dilution method in the determination of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The bioactive components of the extracts were determined using standard techniques and the inhibitory activities of the extracts were compared to gentamicin, ciprofloxacin, erythromycin, azithromycin, ofloxacin, and nitrofurantoin. The MIC of the extract on the test organisms ranges from 10 mg/ml - 40 mg/ml. The sensitivity test showed that the organisms were susceptible to Psidium guajava leave extract except Pseudomonas aeruginosa. The phytochemical analysis of the extracts revealed the presence of bioactive compounds such as Tannin, Saponin, Balsam, Flavonoids, Alkaloids, Cardiac glycosides, Carbohydrate, Resins, Terpenes, and Sterols. It has been shown that the leaves of Psidium guajava have antibacterial effects and hence can be used to treat the ailments caused by those organisms at a particular dosage and concentration. However, more research work on its toxicity level, synergistic or antagonistic interaction with other plants or drugs is needed to consolidate its usage.
