Background:Bacillus cereus is an important pathogen that causes human food poisoning,specifically diarrhea and vomiting.B.cereus can also induce mastitis in dairy cows and has a strong survival ability in milk,as it c...Background:Bacillus cereus is an important pathogen that causes human food poisoning,specifically diarrhea and vomiting.B.cereus can also induce mastitis in dairy cows and has a strong survival ability in milk,as it cannot be inactivated by high-temperature short-time pasteurization.Therefore,B.cereus can enter the market through pasteurized milk and other dairy products,imposing enormous hidden dangers on food safety and human health.Results:In this study,B.cereus 2101(BC)was isolated from milk samples of cows with mastitis.BC grew rapidly with strong hemolysis,making it difficult to prevent mastitis and ensure food security.MAC-T cells were treated with BC and/or Lactobacillus rhamnosus GR-1(LGR-1).Pretreatment with LGR-1 protected the integrity of tight junctions and the expression of zonula occludens-1(ZO-1)and occludin destroyed by BC.Furthermore,LGR-1 pretreatment reduced the expression of NOD-like receptor family member pyrin domain-containing protein 3(NLRP3),caspase recruitment and activation domain(ASC),Caspase-1 p20,gasdermin D(GSDMD)p30,inflammatory factors(interleukin(IL)-1βand IL-18),and cell death induced by BC.Moreover,LGR-1 pretreatment reduced NLRP3 inflammasome activity and increased expressions of ZO-1 and occludin induced by lipopolysaccharides(LPS)+ATP stimulation.MAC-T cells were transfected with NLRP3 si RNA or MCC950 and/or treated with BC and/or LGR-1.NLRP3-si RNA transfection and MCC950 attenuated BC-induced NLRP3 inflammasome activity.Expression of inflammatory cytokines and cell death suggested that the inflammatory pathway might play an important role in the induction of the NLRP3 inflammasome by BC and the protection of LGR-1.Conclusions:These results suggest that LGR-1 might be a probiotic alternative to antibiotics and could be administered to prevent mastitis in dairy cows,thus ensuring food security.展开更多
Although biofilm formation may promote growth,biofilms are not always beneficial to their hosts.The biofilm formation characteristics of Bacillus cereus WPySW2 and its changes at different temperatures were studied.Re...Although biofilm formation may promote growth,biofilms are not always beneficial to their hosts.The biofilm formation characteristics of Bacillus cereus WPySW2 and its changes at different temperatures were studied.Results show that B.cereus WPySW2 promoted the growth of Neoporphyra haitanensis(an economically cultivated seaweed)at 20℃ but accelerated algal rot at 28℃.Thicker B.cereus WPySW2 biofilms covered the surface of N.haitanensis thalli at 28℃,which hindered material exchange between the algae and surrounding environment,inhibited algal photosynthesis and respiration,and accelerated algal decay.Compared with planktonic bacteria,mature biofilm cells had lower energy consumption and metabolic levels.The biofilm metabolic characteristics of B.cereus WPySW2 changed significantly with temperature.High temperature accelerated biofilm maturation,which made it thicker and more stable,allowing the bacteria to easily adapt to environmental changes and obtain greater benefits from their host.High temperature did not affect the production or increased the abundance of toxic metabolites,indicating that the negative effects of B.cereus WPySW2 on algae were not caused by toxins.This study shows that increased temperature can transform a harmless bacterium into a detrimental one,demonstrating that temperature may change the ecological function of phycospheric bacteria by affecting their morphology and metabolism.展开更多
16S rDNA and ERIC(Enterobacteia Repetitive Intergenic Consensus Sequences) based on PCR method were tested for the effectiveness of the differentiation of B.thuringiensis and B.cereus.16S rDNA-PCR primers were designe...16S rDNA and ERIC(Enterobacteia Repetitive Intergenic Consensus Sequences) based on PCR method were tested for the effectiveness of the differentiation of B.thuringiensis and B.cereus.16S rDNA-PCR primers were designed based on the sequence difference in variable regions of B.cereus 16S rDNA and B.thuringiensis 16S rDNA.16S rDNA-PCR showed no obvious difference between B.cereus and B.thuringiensis.The only difference was that one 1600-bp amplificon could be obtained from all the three B.Cereus strains,and none amplificon from any B.thuringiensis strains.ERIC was optimized based on previous reports.The genomic DNA was used for the template of ERIC-PCR,and the following DNA fingerprints were analyzed by the agarose gel electrophoresis.The results showed that DNA fingerprint of three B.thuringiensis strains had a unique amplicon less than 100-bp,while DNA fingerprint of three B.cereus strains had none.Moreover,DNA fingerprint of B.cereus showed a 700-bp amplicon,but didn't have any DNA fingerprints of B.thuringiensis genome.Therefore,ERIC-PCR technique should be able to be used for the differentiation of B.thuringiensis and B.cereus.展开更多
A short phylogenetic marker previously used in the reconstruction of the Order Bacillales and the genus Bacillus was assessed here at a lower taxa level: species in the Bacillus cereus group: B. anthracis, B. cereus, ...A short phylogenetic marker previously used in the reconstruction of the Order Bacillales and the genus Bacillus was assessed here at a lower taxa level: species in the Bacillus cereus group: B. anthracis, B. cereus, B. thuringiensis and B. weihenstephanensis. This maker is 220 bp in length. It is a combination of 150 bp at the 3’ end of the 16S rDNA and 70 bp at the 5’ end of the 16S-23S ITS sequence. Three additional Bacillus species, B. halodurans, B. licheniformis and B. subtilis, and Clostridium tetani were included for comparison purposes. A total of eight bacterial species and 12 strains were analyzed. A boot- strapped neighbor-joining tree was inferred from comparative analyses of all allelic sequences of the bacterial species and strains under study. Based on its topology, four major Groups were revealed at the 90% nucleotide sequence identities, Group I to IV. Group I contains all al-leles of the Bacillus cereus group. Group II con-tains all alleles of B. halodurans. Group III con-tains all alleles of B. licheniformis and B. subtilis. Group IV contains all alleles of Clostridium tetani. The 220 bp phylogenetic marker used here could resolve different species from different genera. At the genus level, distant species could be dis-tinguished. Very closely-related species, however, were undistinguishable. Species in the B. cereus group, most notably B. cereus, B. anth- racis and B. thuringiensis, could not be distin- guished. After successfully inferring the phylo- genies of the Order Bacillales and the genus Bacillus, we have met the resolving limit of this short phy-logenetic marker: B. cereus, B. anthracis and B. thuringiensis.展开更多
sodA2-encoding manganese-containing superoxide dismutase(MnSOD2)in Bacillus cereus 905 plays an essential role in antioxidative stress,nutrition utilization,rhizosphere and phyllosphere colonization.However,the genes ...sodA2-encoding manganese-containing superoxide dismutase(MnSOD2)in Bacillus cereus 905 plays an essential role in antioxidative stress,nutrition utilization,rhizosphere and phyllosphere colonization.However,the genes involved in regulating the sod A2 expression have not been clearly elucidated in B.cereus.In this study,a genome-wide random insertion mutagenesis was constructed by using transposon TnYLB-1 to identify novel genes regulating the sodA2 expression.Seven mutants that changed the sodA2 expression at both m RNA and protein levels were finally obtained.Sequence analysis and BLAST data showed that the genes disrupted by TnYLB-1 in B.cereus 905 shared high conservations with those in the B.cereus type strain,ATCC 14579.These genes encode heat-inducible transcription repressor,chloride channel protein,recombinase A,ferrous iron transport protein,nucleoside diphosphate kinase,and histidine ammonia-lyase.Besides,we also provided the evidence that the genes regulating the sodA2 expression could influence colonization ability of B.cereus 905 on wheat roots.Specifically,those genes downregulating the sodA2 expression significantly reduced bacterial colonization on wheat roots,and mutants with increased MnSOD2 activities could enhance bacterial population densities on wheat roots to a certain degree.Our work provided information that multiple genes are involved in MnSOD2 production and wheat root colonization.The molecular regulatory pathways through which these genes modulate the sod A2 expression and root colonization need to be investigated extensively in the future.展开更多
In order to explore the salt tolerance mechanism of Bacillus cereus LBR-4 with salinity of 14%NaCl,differential proteomic analysis of the whole protein of LBR-4 strain expressed under 14%NaCl high salinity condition a...In order to explore the salt tolerance mechanism of Bacillus cereus LBR-4 with salinity of 14%NaCl,differential proteomic analysis of the whole protein of LBR-4 strain expressed under 14%NaCl high salinity condition and normalculture condition(1%NaCl)was studied by two-dimensional electrophoresis and mass spectrometry.The isoelectric point of most detected proteins was between pH 4-7 and the molecular weight distribution was 10-70 ku.Compared with the normal culture condition,the expression level of 118 protein spots in the whole protein expression map changed significantly(accounting for 25.2%of the total protein spots).The expression level of 78 protein spots increased significantly,including 22 new protein spots that appeared under high salt stress.The expression levels of 40 protein spots decreased significantly,including 18 protein spots that disappeared under high salt stress.By mass spectrometry,six distinct differentially expressed protein spotswere dihydroxy acid dehydratase,cell division protein FtsZ,iron sulfur cluster synthesis protein SufD,unknown carboxylase YngE,hypothetical acetaldehyde dehydrogenase DhaS and phenylalanine acid tRNA ligase alpha subunit.It was speculated that under high salt stress,the cells had protective measures and the secretion of intracellular compatible solutes increased.The iron and sulfur clusters involved in various physiological reactions also activated the stressful suf synthesis pathway,and therate of cell division and reproduction was also slowed down and ensured the normal progress of physiological reactions inthe cells.展开更多
Introduction: Bacillus cereus and spores produced in various ecological niches are responsible for toxic infections in humans. This study is conducted to determine the antibiotics resistance profile of B. cereus strai...Introduction: Bacillus cereus and spores produced in various ecological niches are responsible for toxic infections in humans. This study is conducted to determine the antibiotics resistance profile of B. cereus strains isolated from soil and pepper consummated in Brazzaville. Methodology: An antimicrobial susceptibility test of 16 B. cereus strains from soil and peppers was performed using 11 antibiotics by the Kirby-Bauer’s diffusion on disc method. Results: Results revealed 100% (16/16) of resistance in penicillin G, amoxicillin, ceftazidime, rifampicin, and colistin, also 18.75% (3/16), 11.76% (2/16), and 18.75% (3/16) of resistance in doripenem, vancomycin and chloramphenicol respectively. In addition, we have observed 100% (16/16), 81.25% (13/16), 76.47% (13/16), 35.29% (5/16), 35.50% (6/16), and 12.5% (2/16) of sensitivity to line-zolid, tigecycline, ciprofloxacin, vancomycin, doripenem and chloram-phenicol respectively. However, all strains have been multidrug resistant (MDR) to betalactams, polypeptides, and ansamycins. Moreover, 7 strains (43.75%) have been variably multiresistant. One strain, Ri10 has been resistant to beta-lactams, polypeptides, ansamycins, cyclins and glycopeptides. No strain was ultraresistant (XDR) or largely insensitive (PDR) to different antibiotics. Conclusion: This study reveals that 51% of strains have been resistant to antibiotics, 32% are sensitive, and 17% have intermediate resistance. These results partly explain the high rate of gastroenteritis observed in Brazzaville due to food poisoning.展开更多
Bacillus cereus 58(Bc58)is a UV-resistant wild type strain that has an ability to produce a sorrel pigment induced by L-tyrosine.The Fourier-transform infrared(FT-IR)spectra and chemical tests of its pigment are simil...Bacillus cereus 58(Bc58)is a UV-resistant wild type strain that has an ability to produce a sorrel pigment induced by L-tyrosine.The Fourier-transform infrared(FT-IR)spectra and chemical tests of its pigment are similar to that of the standard melanin(Sigma).A bioassay shows that the LC50 of a Bacillus thuringiensis(Bt)formulation added with the melanin of Bc58 and exposed to UV for 5 h is 16.1μg/m1,which is similar to that of the Bt formulation without UV treatment,however,it is almost double that of the Bt formulation exposed to UV without the melanin of Bc58.The result of SDS-PAGE indicates that the melanin of Bc58 can protect the insecticidal crystal proteins from degradation.This suggests that it is an excellent UV protective agent for the insecticidal crystal proteins of the Bt formulation.展开更多
Introduction:Raw milk is the basic raw material of dairy products.Bacillus cereus(B.cereus)is a typical conditional pathogenic bacteria and cold-phagocytic spoilage bacteria in raw milk.Materials and Methods:In this s...Introduction:Raw milk is the basic raw material of dairy products.Bacillus cereus(B.cereus)is a typical conditional pathogenic bacteria and cold-phagocytic spoilage bacteria in raw milk.Materials and Methods:In this study,a quantitative polymerase chain reaction(qPCR)method for detecting B.cereus in raw milk was established.The specificity of the method was verified by using other Bacillus bacteria and pathogenic bacteria;the sensitivity of the method was evaluated by preparing recombinant plasmids and simulated contaminated samples;and the applicability of the method was verified using pure spore DNA.The actual sample detection was completed by using the established qPCR method.Results:The qPCR established in this study can specifically detect B.cereus in raw milk.The limit of detection of the method was as low as 200 CFU/mL,the limit of quantification ranged from 2×10^(2)to 2×10^(8)CFU/mL,and the amplification efficiency of qPCR was 96.6%.Conclusions:The method established in this study can distinguish B.cereus from other Bacillus bacteria,and spore DNA can be used as the detection object.This method has the advantages of strong specificity,high sensitivity,wide application range,and short detection time,which isexpectedtobeapplied in thedairy industry.展开更多
In order to enhance the degrading protein capability of purple non-sulfur bacteria(PNSB),an effective strain,L2,was used to co-culture with Rhodobacter sphaeroides ATCC17023.The effects of added strain on protein remo...In order to enhance the degrading protein capability of purple non-sulfur bacteria(PNSB),an effective strain,L2,was used to co-culture with Rhodobacter sphaeroides ATCC17023.The effects of added strain on protein removal of R.sphaeroides were investigated.Results showed that strain L2,being identified as Bacillus thuringiensis/cereus,had a high potential for producing protease with a production of 295 U/m L.The optimal B.thuringiensis/cereus(40 μL) could significantly increase protein degradation of R.sphaeroides.Protein removal and biomass production were improved by 483% and 67%,respectively.R.sphaeroides/total biomass production was more than 95%.Theoretical analysis revealed that R.sphaeroides syntrophically interacted with B.thuringiensis/cereus.Protein degradation of B.thuringiensis/cereus provided small molecule substrates(VFAs) for R.sphaeroides growth and cells materials synthesis.展开更多
Bacillus cereus,a spore-forming bacterium and frequent cause of food poisoning,poses a safety threat to dairy and rice industries due to its high contamination rates and ability to produce toxins such as cereulide.Bec...Bacillus cereus,a spore-forming bacterium and frequent cause of food poisoning,poses a safety threat to dairy and rice industries due to its high contamination rates and ability to produce toxins such as cereulide.Because of widespread presence and thermal resistance of the spores,B.cereus cannot be eliminated from the environment and may survive in processing plants.Surviving spores can develop into vegetative cells,leading to a heightened risk of cereulide production in the processing environment.Both spores and vegetative cells have the ability to adhere to the surfaces of dairy plants and form biofilms,serving as the site for cereulide production and accumulation.Therefore,it is crucial for the food industry to address potential sources and pathways of B.cereus contamination and their connections to cereulide production in processing lines.In this review,sources of contamination of B.cereus,including spores,vegetative cells,and biofilms and their potential role in cereulide production at each stage of dairy and cooked rice processing were analyzed.In addition,control methods to prevent B.cereus contamination and cereulide production in processing lines were proposed,offering valuable insights for improving microbial risk management in the food industry.展开更多
Background:Previous studies found differences in the utilization of different carbon sources during biofilm formation by Bacillus cereus.Illumina HiSeq high-throughput sequencing technology was used to investigate the...Background:Previous studies found differences in the utilization of different carbon sources during biofilm formation by Bacillus cereus.Illumina HiSeq high-throughput sequencing technology was used to investigate the changes in gene transcript levels in Bacillus cereus biofilm bacteria under different carbon source conditions.Results:Compared with the control group,the number of differentially expressed genes in the glucose,maltose,lactose,and skim milksupplemented groups was 351,1136,133,and 487,respectively.The results showed that the pathways involved in the differentially expressed genes were mainly distributed in glycolysis and pentose phosphate pathway,tricarboxylic acid cycle,amino acid metabolism,and fatty acid metabolism.The gene expression of enzymes related to acetoin synthesis from pyruvate was mostly upregulated in the glucose-supplemented group.The gene expression of enzymes related to pyruvate synthesis of branched-chain amino acids in the maltose-supplemented group was mostly upregulated.In the lactose-supplemented group,the gene expression of acetoin biosynthesis from pyruvate was upregulated.Pyruvate production through glycolysis pathway increased in the skim milk-supplemented group,but the metabolic capacity of the tricarboxylic acid cycle did not change significantly.Conclusion:The content of pyruvate stored by Bacillus cereus biofilm bacteria through glycolysis or pentose phosphate pathway increased,but the carbon flux into the tricarboxylic acid cycle did not increase,which suggested that carbon fluxes in the extracellular polysaccharide synthesis pathway of the biofilm may be increased,resulting in increased biofilm biomass formation.展开更多
Fermented foods play a very important role in Cambodian health and nutrition,as well as other developing countries where food preservation methods may be limited.SIENG,a Khmer fermented soybean product,naturally conta...Fermented foods play a very important role in Cambodian health and nutrition,as well as other developing countries where food preservation methods may be limited.SIENG,a Khmer fermented soybean product,naturally contains both beneficial and pathogenic microorganisms.Traditional fermentation that relies on natural microbial flora and environmental conditions results in variable product quality and can lead to spoilage.A starter culture such as Bacillus subtilis can ensure the safety and stability of the products.The objective of this study is to control the growth of Gram positive pathogens contaminated into traditional fermented soybean(SEING)by using antimicrobial Bacillus subtilis isolated from the same kind of food.Out of 120 SIENG samples,49 B.cereus strains were isolated,and 12 of B.cereus were positively synthesized compared with the lyophilized control enterotoxin.Two of these strains(BTM8-7 and BTM8-8)produced high levels of enterotoxin.We identified five Bacillus strains with the ability to fight against indicator pathogenic microorganisms.Among the five strains,B.CeM6-2 had the highest activity level against Lactobacillus plantrum ATCC 8014 and the largest diameter.B.CeM6-2 tolerated up to 20 h at 30℃ and 22 h at 37℃.In testing the strains with PK and PK-PMSF enzymes,bacteriocin produced by the strain B.CeM6PK untreated and B.CeM6-2PK-PMSF had a significantly stronger ability to suppress all the pathogenic indicators from 0 h to 47 h compared to the B.CeM6-2PK.Moreover,CeM6-2 outperformed the Miyagino strains,as it actively produced bacteriocin that fought against all four indicator strains of Gram positive and lactic acid groups,especially against Listeria monocytogenes,Streptococcus pyrogene,Leuconostoc mesenterids and L.plantarum,from 0 h-58 h and 0 h-40 h at 35℃.CeM6-2(1%)strain had the highest ability to fight against B.cereus at 24 h and at 34 h to 44 h incubation as well.CeM6-2(10:0 mL)and CeM6-2(9:1 mL)have the strongest ability to fight against B.cereus at room temperature(48 h and 72 h).The longer incubation and time at room temperature produce the highest level of bacteriocin.Thus,bacteriocins produced by B.CeM6-2 can be used as a preservative in food processing industries to avoid food spoilage even in higher temperatures and time.展开更多
Garlic is a most important medicinal herb belonging to the family Liliaceae. Both its leaves and bulb are edible. The current study was based on evaluating the growth promoting potential of plant growth promoting rhiz...Garlic is a most important medicinal herb belonging to the family Liliaceae. Both its leaves and bulb are edible. The current study was based on evaluating the growth promoting potential of plant growth promoting rhizobacteria (PGPR) on garlic (Allium sativum L.) growth and biochemical contents. Garlic cloves were inoculated with 3 kinds of PGPRs, Pseudomonas putida (KX574857), Pseudomonas stutzeri (Kx574858) and Bacillus cereus (ATCC14579) at 10<sup>8</sup> cells/mL prior to sowing. Under natural conditions, plants were grown in the net house. The PGPR significantly enhanced % germination, leaf and root growth and their biomass also increased the diameter of bulb and fresh and dry weight. The flavonoids, phenolics, chlorophyll, protein and sugar content were also significantly increased due to PGPR inoculation. The Pseudomonas stutzeri was found most effective for producing longer leaves with moderate sugar, high flavonoids (129%) and phenolics (263%) in bulb over control (Tap). The Pseudomonas putida exhibited a maximum increase in bulb diameter and bulb biomass with maximum phenolics and flavonoid contents.展开更多
Rhizosphere microbial communities play important roles in facilitating or inhibiting the establishment of exotic species.Since some invasive plants interact with soil microbial communities such as rhizosphere bacteria...Rhizosphere microbial communities play important roles in facilitating or inhibiting the establishment of exotic species.Since some invasive plants interact with soil microbial communities such as rhizosphere bacteria,changes triggered by rhizosphere bacteria may alter competitive interactions between exotic and native plants.This study compared the Bacillus cereus content in soils with different degrees of Ageratina adenophora invasion,and investigated the effects of A.adenophora allelochemicals on B.cereus growth and soil characteristics and the feedback effects of B.cereus on A.adenophora growth.Bacillus cereus content in the rhizosphere of A.adenophora increased with intensification of the invasion process,and newly invaded soil contained almost twice as much bacteria as noninvaded soil.When rhizosphere soil was added to the root exudates of A.adenophora,the contents of B.cereus were twice as much as the control,except on the first day.Certain soil parameters increased significantly,such as ammonium nitrogen(NH_(4)^(+)-N)and available phosphorus(AP),which were increased by 41 and 27%,respectively.Soil treatment with B.cereus promoted the degradation of two allelochemicals from the rhizosphere of A.adenophora,amorpha-4,7(11)-dien-8-one and 6-hydroxy-5-isopropy1-3,8-dimethyl-4 a,5,6,7,8,8 ahexahydraphthalen-2(1 H)-one,to varying degrees;and increased the germination rate by 50%,root length by 117%,shoot length by 48%and fresh weight by 81%for A.adenophora compared to those of untreated soil.Our results confirmed that the invasion of A.adenophora will promote an increase of B.cereus,a beneficial rhizosphere bacterium,which in turn induces a positive feedback effect on A.adenophora.展开更多
The development of green experimental processes for the synthesis of nanoparticles is a need in the field of nanotechnology. The synthesis of silver nanoparticles was achieved using Bacillus cereus supernatant and1 m ...The development of green experimental processes for the synthesis of nanoparticles is a need in the field of nanotechnology. The synthesis of silver nanoparticles was achieved using Bacillus cereus supernatant and1 m M silver nitrate. 100 m M glucose was found to quicken the rate of reaction of silver nanoparticles synthesis.UV-visible spectrophotometric analysis was carried out to assess the synthesis of silver nanoparticles. The synthesized silver nanoparticles were further characterized by using Nanoparticle Tracking Analyzer(NTA),Transmission Electron Microscope and Energy Dispersive X-ray spectra. These silver nanoparticles showed enhanced quorum quenching activity against Staphylococcus aureus biofilm and prevention of biofilm formation which can be seen under inverted microscope(40 X). The synergistic effect of silver nanoparticles along with antibiotics in biofilm quenching was found to be effective. In the near future, silver nanoparticles could be used in the treatment of infections caused by highly antibiotic resistant biofilm.展开更多
BACKGROUND Phlegmonous gastritis(PG)is a rare bacterial infectious disease characterized by neutrophil-based purulent inflammation of the gastric wall.The most representative causative bacterium is Streptococcus pyoge...BACKGROUND Phlegmonous gastritis(PG)is a rare bacterial infectious disease characterized by neutrophil-based purulent inflammation of the gastric wall.The most representative causative bacterium is Streptococcus pyogenes,followed by Staphylococcus,Pneumococcus and Enterococcus.Hepatic portal venous gas(HPVG)is considered a potentially fatal condition and is rarely associated with PG.CASE SUMMARY The white blood cell count of a 70-year-old woman with acute lymphocytic leukemia in complete remission dropped to 100/μL after consolidation chemotherapy.Her vital signs were consistent with septic shock.Venous blood culture revealed the presence of Bacillus cereus.Abdominal computed tomography(CT)and esophagogastroduodenoscopy(EGD)showed marked thickening of the gastric wall.As with the other findings,CT was suggestive of HPVG,and EGD showed pseudomembrane-like tissue covering the superficial mucosa.Histopathological examination of gastric biopsy specimens showed mostly necrotic tissue with lymphocytes rather than neutrophils.Culture of gastric specimens revealed the presence of Bacillus cereus.We finally diagnosed this case as PG with Bacillus cereus-induced sepsis and HPVG.This patient recovered successfully with conservative treatment,chiefly by using carbapenem antibiotics.CONCLUSION The histopathological finding of this gastric biopsy specimen should be called"neutropenic necrotizing gastritis".展开更多
Antibacterial activity of methanol, n-hexane and water extracts of seeds and bark of Moringa oleifera and Moringa ovalifolia was conducted. The causative agents of common bacterial infections that are thought to cause...Antibacterial activity of methanol, n-hexane and water extracts of seeds and bark of Moringa oleifera and Moringa ovalifolia was conducted. The causative agents of common bacterial infections that are thought to cause water-borne diseases, namely, Escherichia coli, Enterococcus faecalis, and Bacillus cereus were chosen for the study. The paper-disc diffusion method was used with treatments arranged in a completely randomized design and replicated four times. The M. oleifera extracts showed more inhibitory effect than those of M. ovolifolia. The conventional antibiotic Ampicilin generally showed higher inhibitory effect than the extracts of both M. oleifera and M. ovalifolia. The inhibitory effect varied depending on the solvent used. The n-hexane extracts of both seeds and bark of M. ovalifolia and M. oleifera had almost the same inhibition activities (6 ± 1 mm mean inhibition zones) on B. cereus, E. coli and E. faecalis. The n-hexane extract generally gave lower antibacterial activities than those of the other solvents for seeds and back. The results of the study showed that M. oleifera and M. ovalifolia had a degree of antibacterial properties against the selected test organisms that cause water borne diseases.展开更多
Phytoextraction is a promising option for purifying hexavalent chromium(Cr(Ⅵ))-laden wastewater,but the long remediation period incurred by poor growth rate of Cr hyperaccumulators remains a primary hindrance to its ...Phytoextraction is a promising option for purifying hexavalent chromium(Cr(Ⅵ))-laden wastewater,but the long remediation period incurred by poor growth rate of Cr hyperaccumulators remains a primary hindrance to its large-scale application.In this study,we performed a hydroponic experiment to evaluate the feasibility of promoting the growth and phytoextraction efficiency of Cr hyperaccumulator Leersia hexandra Swartz(L.hexandra)by inoculating plant growth-promoting rhizobacteria(PGPR)Bacillus cereus(B.cereus).In batch tests,the Cr(Ⅵ)removal rates of L.hexandra and B.cereus co-culture were greater than the sum of their respective monocultures.This was likely due to the microbial reduction of Cr(Ⅵ)to Cr(Ⅲ),which is amiable to plant uptake.Besides,the PGPR factors of B.cereus,including indoleacetic acid(IAA)production,1-aminocyclopropane-1-carboxylic acid deamination(ACCd)activity,phosphate solubilization capacity,and siderophore production,were quantified.These PGPR factors helped explain the biomass augmentation,root elongation and enhanced Cr enrichment of the inoculated L.hexandra in pot experiments.Despite the increased Cr uptake,no aggravated oxidative damage to the cell membrane was observed in the inoculated L.hexandra.This was attributed to its capacity to confront the increased intracellular Cr stress by upregulating both the activities of antioxidative enzymes and expression of metal-binding proteins/peptides.Moreover,L.hexandra could always conserve the majority of Cr in the residual and oxalic integrated forms with low mobility and phytotoxicity,irrespective of the B.cereus inoculation.These results highlight the constructed Cr hyperaccumulatorrhizobacteria consortia as an effective candidate for decontaminating Cr(Ⅵ)-laden wastewater.展开更多
基金the following funds:the National Key R&D Program of China(Project No.2017YFD0502200)the National Natural Science Foundation of China(Project No.31960721)the National Natural Science Foundation of China(Project No.31873034)。
文摘Background:Bacillus cereus is an important pathogen that causes human food poisoning,specifically diarrhea and vomiting.B.cereus can also induce mastitis in dairy cows and has a strong survival ability in milk,as it cannot be inactivated by high-temperature short-time pasteurization.Therefore,B.cereus can enter the market through pasteurized milk and other dairy products,imposing enormous hidden dangers on food safety and human health.Results:In this study,B.cereus 2101(BC)was isolated from milk samples of cows with mastitis.BC grew rapidly with strong hemolysis,making it difficult to prevent mastitis and ensure food security.MAC-T cells were treated with BC and/or Lactobacillus rhamnosus GR-1(LGR-1).Pretreatment with LGR-1 protected the integrity of tight junctions and the expression of zonula occludens-1(ZO-1)and occludin destroyed by BC.Furthermore,LGR-1 pretreatment reduced the expression of NOD-like receptor family member pyrin domain-containing protein 3(NLRP3),caspase recruitment and activation domain(ASC),Caspase-1 p20,gasdermin D(GSDMD)p30,inflammatory factors(interleukin(IL)-1βand IL-18),and cell death induced by BC.Moreover,LGR-1 pretreatment reduced NLRP3 inflammasome activity and increased expressions of ZO-1 and occludin induced by lipopolysaccharides(LPS)+ATP stimulation.MAC-T cells were transfected with NLRP3 si RNA or MCC950 and/or treated with BC and/or LGR-1.NLRP3-si RNA transfection and MCC950 attenuated BC-induced NLRP3 inflammasome activity.Expression of inflammatory cytokines and cell death suggested that the inflammatory pathway might play an important role in the induction of the NLRP3 inflammasome by BC and the protection of LGR-1.Conclusions:These results suggest that LGR-1 might be a probiotic alternative to antibiotics and could be administered to prevent mastitis in dairy cows,thus ensuring food security.
基金Supported by the Zhejiang Province Nature Science Foundation of China(No.LY22C190002)the National Natural Science Foundation of China(Nos.31772871,31872540)+4 种基金the Major Scientific and Technological Project of Zhejiang Province(No.2021C02069-9)the Major Scientific and Technological Project of Ningbo(Nos.2021Z004,2021Z103)the Scientific and Technological Project of Ningbo(No.2021S063)the China Agriculture Research System of MOF and MARAthe K.C.Wong Magna Fund of Ningbo University。
文摘Although biofilm formation may promote growth,biofilms are not always beneficial to their hosts.The biofilm formation characteristics of Bacillus cereus WPySW2 and its changes at different temperatures were studied.Results show that B.cereus WPySW2 promoted the growth of Neoporphyra haitanensis(an economically cultivated seaweed)at 20℃ but accelerated algal rot at 28℃.Thicker B.cereus WPySW2 biofilms covered the surface of N.haitanensis thalli at 28℃,which hindered material exchange between the algae and surrounding environment,inhibited algal photosynthesis and respiration,and accelerated algal decay.Compared with planktonic bacteria,mature biofilm cells had lower energy consumption and metabolic levels.The biofilm metabolic characteristics of B.cereus WPySW2 changed significantly with temperature.High temperature accelerated biofilm maturation,which made it thicker and more stable,allowing the bacteria to easily adapt to environmental changes and obtain greater benefits from their host.High temperature did not affect the production or increased the abundance of toxic metabolites,indicating that the negative effects of B.cereus WPySW2 on algae were not caused by toxins.This study shows that increased temperature can transform a harmless bacterium into a detrimental one,demonstrating that temperature may change the ecological function of phycospheric bacteria by affecting their morphology and metabolism.
基金Supported by Genetically Modified Organisms Breeding Major Projects (2009ZX08009-031B)State Key Laboratory for Biology of Plant Diseases and Insect Pests Open Fund (DKL2010OP13)
文摘16S rDNA and ERIC(Enterobacteia Repetitive Intergenic Consensus Sequences) based on PCR method were tested for the effectiveness of the differentiation of B.thuringiensis and B.cereus.16S rDNA-PCR primers were designed based on the sequence difference in variable regions of B.cereus 16S rDNA and B.thuringiensis 16S rDNA.16S rDNA-PCR showed no obvious difference between B.cereus and B.thuringiensis.The only difference was that one 1600-bp amplificon could be obtained from all the three B.Cereus strains,and none amplificon from any B.thuringiensis strains.ERIC was optimized based on previous reports.The genomic DNA was used for the template of ERIC-PCR,and the following DNA fingerprints were analyzed by the agarose gel electrophoresis.The results showed that DNA fingerprint of three B.thuringiensis strains had a unique amplicon less than 100-bp,while DNA fingerprint of three B.cereus strains had none.Moreover,DNA fingerprint of B.cereus showed a 700-bp amplicon,but didn't have any DNA fingerprints of B.thuringiensis genome.Therefore,ERIC-PCR technique should be able to be used for the differentiation of B.thuringiensis and B.cereus.
文摘A short phylogenetic marker previously used in the reconstruction of the Order Bacillales and the genus Bacillus was assessed here at a lower taxa level: species in the Bacillus cereus group: B. anthracis, B. cereus, B. thuringiensis and B. weihenstephanensis. This maker is 220 bp in length. It is a combination of 150 bp at the 3’ end of the 16S rDNA and 70 bp at the 5’ end of the 16S-23S ITS sequence. Three additional Bacillus species, B. halodurans, B. licheniformis and B. subtilis, and Clostridium tetani were included for comparison purposes. A total of eight bacterial species and 12 strains were analyzed. A boot- strapped neighbor-joining tree was inferred from comparative analyses of all allelic sequences of the bacterial species and strains under study. Based on its topology, four major Groups were revealed at the 90% nucleotide sequence identities, Group I to IV. Group I contains all al-leles of the Bacillus cereus group. Group II con-tains all alleles of B. halodurans. Group III con-tains all alleles of B. licheniformis and B. subtilis. Group IV contains all alleles of Clostridium tetani. The 220 bp phylogenetic marker used here could resolve different species from different genera. At the genus level, distant species could be dis-tinguished. Very closely-related species, however, were undistinguishable. Species in the B. cereus group, most notably B. cereus, B. anth- racis and B. thuringiensis, could not be distin- guished. After successfully inferring the phylo- genies of the Order Bacillales and the genus Bacillus, we have met the resolving limit of this short phy-logenetic marker: B. cereus, B. anthracis and B. thuringiensis.
基金the grants from the National Natural Science Foundation of China(31701860)the Program of Science and Technology of Beijing,China(Z191100004019025)。
文摘sodA2-encoding manganese-containing superoxide dismutase(MnSOD2)in Bacillus cereus 905 plays an essential role in antioxidative stress,nutrition utilization,rhizosphere and phyllosphere colonization.However,the genes involved in regulating the sod A2 expression have not been clearly elucidated in B.cereus.In this study,a genome-wide random insertion mutagenesis was constructed by using transposon TnYLB-1 to identify novel genes regulating the sodA2 expression.Seven mutants that changed the sodA2 expression at both m RNA and protein levels were finally obtained.Sequence analysis and BLAST data showed that the genes disrupted by TnYLB-1 in B.cereus 905 shared high conservations with those in the B.cereus type strain,ATCC 14579.These genes encode heat-inducible transcription repressor,chloride channel protein,recombinase A,ferrous iron transport protein,nucleoside diphosphate kinase,and histidine ammonia-lyase.Besides,we also provided the evidence that the genes regulating the sodA2 expression could influence colonization ability of B.cereus 905 on wheat roots.Specifically,those genes downregulating the sodA2 expression significantly reduced bacterial colonization on wheat roots,and mutants with increased MnSOD2 activities could enhance bacterial population densities on wheat roots to a certain degree.Our work provided information that multiple genes are involved in MnSOD2 production and wheat root colonization.The molecular regulatory pathways through which these genes modulate the sod A2 expression and root colonization need to be investigated extensively in the future.
基金Supported by Heilongjiang Province National Science Foundation(LH2020C007)。
文摘In order to explore the salt tolerance mechanism of Bacillus cereus LBR-4 with salinity of 14%NaCl,differential proteomic analysis of the whole protein of LBR-4 strain expressed under 14%NaCl high salinity condition and normalculture condition(1%NaCl)was studied by two-dimensional electrophoresis and mass spectrometry.The isoelectric point of most detected proteins was between pH 4-7 and the molecular weight distribution was 10-70 ku.Compared with the normal culture condition,the expression level of 118 protein spots in the whole protein expression map changed significantly(accounting for 25.2%of the total protein spots).The expression level of 78 protein spots increased significantly,including 22 new protein spots that appeared under high salt stress.The expression levels of 40 protein spots decreased significantly,including 18 protein spots that disappeared under high salt stress.By mass spectrometry,six distinct differentially expressed protein spotswere dihydroxy acid dehydratase,cell division protein FtsZ,iron sulfur cluster synthesis protein SufD,unknown carboxylase YngE,hypothetical acetaldehyde dehydrogenase DhaS and phenylalanine acid tRNA ligase alpha subunit.It was speculated that under high salt stress,the cells had protective measures and the secretion of intracellular compatible solutes increased.The iron and sulfur clusters involved in various physiological reactions also activated the stressful suf synthesis pathway,and therate of cell division and reproduction was also slowed down and ensured the normal progress of physiological reactions inthe cells.
文摘Introduction: Bacillus cereus and spores produced in various ecological niches are responsible for toxic infections in humans. This study is conducted to determine the antibiotics resistance profile of B. cereus strains isolated from soil and pepper consummated in Brazzaville. Methodology: An antimicrobial susceptibility test of 16 B. cereus strains from soil and peppers was performed using 11 antibiotics by the Kirby-Bauer’s diffusion on disc method. Results: Results revealed 100% (16/16) of resistance in penicillin G, amoxicillin, ceftazidime, rifampicin, and colistin, also 18.75% (3/16), 11.76% (2/16), and 18.75% (3/16) of resistance in doripenem, vancomycin and chloramphenicol respectively. In addition, we have observed 100% (16/16), 81.25% (13/16), 76.47% (13/16), 35.29% (5/16), 35.50% (6/16), and 12.5% (2/16) of sensitivity to line-zolid, tigecycline, ciprofloxacin, vancomycin, doripenem and chloram-phenicol respectively. However, all strains have been multidrug resistant (MDR) to betalactams, polypeptides, and ansamycins. Moreover, 7 strains (43.75%) have been variably multiresistant. One strain, Ri10 has been resistant to beta-lactams, polypeptides, ansamycins, cyclins and glycopeptides. No strain was ultraresistant (XDR) or largely insensitive (PDR) to different antibiotics. Conclusion: This study reveals that 51% of strains have been resistant to antibiotics, 32% are sensitive, and 17% have intermediate resistance. These results partly explain the high rate of gastroenteritis observed in Brazzaville due to food poisoning.
文摘Bacillus cereus 58(Bc58)is a UV-resistant wild type strain that has an ability to produce a sorrel pigment induced by L-tyrosine.The Fourier-transform infrared(FT-IR)spectra and chemical tests of its pigment are similar to that of the standard melanin(Sigma).A bioassay shows that the LC50 of a Bacillus thuringiensis(Bt)formulation added with the melanin of Bc58 and exposed to UV for 5 h is 16.1μg/m1,which is similar to that of the Bt formulation without UV treatment,however,it is almost double that of the Bt formulation exposed to UV without the melanin of Bc58.The result of SDS-PAGE indicates that the melanin of Bc58 can protect the insecticidal crystal proteins from degradation.This suggests that it is an excellent UV protective agent for the insecticidal crystal proteins of the Bt formulation.
基金supported by the National Key Research and Development Program of China (2018YFC1604201 and 2018YFC1603800).
文摘Introduction:Raw milk is the basic raw material of dairy products.Bacillus cereus(B.cereus)is a typical conditional pathogenic bacteria and cold-phagocytic spoilage bacteria in raw milk.Materials and Methods:In this study,a quantitative polymerase chain reaction(qPCR)method for detecting B.cereus in raw milk was established.The specificity of the method was verified by using other Bacillus bacteria and pathogenic bacteria;the sensitivity of the method was evaluated by preparing recombinant plasmids and simulated contaminated samples;and the applicability of the method was verified using pure spore DNA.The actual sample detection was completed by using the established qPCR method.Results:The qPCR established in this study can specifically detect B.cereus in raw milk.The limit of detection of the method was as low as 200 CFU/mL,the limit of quantification ranged from 2×10^(2)to 2×10^(8)CFU/mL,and the amplification efficiency of qPCR was 96.6%.Conclusions:The method established in this study can distinguish B.cereus from other Bacillus bacteria,and spore DNA can be used as the detection object.This method has the advantages of strong specificity,high sensitivity,wide application range,and short detection time,which isexpectedtobeapplied in thedairy industry.
基金Sponsored by the National Natural Science Foundation of China(Grant No.51278489)
文摘In order to enhance the degrading protein capability of purple non-sulfur bacteria(PNSB),an effective strain,L2,was used to co-culture with Rhodobacter sphaeroides ATCC17023.The effects of added strain on protein removal of R.sphaeroides were investigated.Results showed that strain L2,being identified as Bacillus thuringiensis/cereus,had a high potential for producing protease with a production of 295 U/m L.The optimal B.thuringiensis/cereus(40 μL) could significantly increase protein degradation of R.sphaeroides.Protein removal and biomass production were improved by 483% and 67%,respectively.R.sphaeroides/total biomass production was more than 95%.Theoretical analysis revealed that R.sphaeroides syntrophically interacted with B.thuringiensis/cereus.Protein degradation of B.thuringiensis/cereus provided small molecule substrates(VFAs) for R.sphaeroides growth and cells materials synthesis.
基金This work was funded by a grant from the Key Projects of International Scientific and Technological Innovation Cooperation Among Governments Under the National Key Research and Development Program of China(No.2019YFE0103800).
文摘Bacillus cereus,a spore-forming bacterium and frequent cause of food poisoning,poses a safety threat to dairy and rice industries due to its high contamination rates and ability to produce toxins such as cereulide.Because of widespread presence and thermal resistance of the spores,B.cereus cannot be eliminated from the environment and may survive in processing plants.Surviving spores can develop into vegetative cells,leading to a heightened risk of cereulide production in the processing environment.Both spores and vegetative cells have the ability to adhere to the surfaces of dairy plants and form biofilms,serving as the site for cereulide production and accumulation.Therefore,it is crucial for the food industry to address potential sources and pathways of B.cereus contamination and their connections to cereulide production in processing lines.In this review,sources of contamination of B.cereus,including spores,vegetative cells,and biofilms and their potential role in cereulide production at each stage of dairy and cooked rice processing were analyzed.In addition,control methods to prevent B.cereus contamination and cereulide production in processing lines were proposed,offering valuable insights for improving microbial risk management in the food industry.
基金supported by the National Natural Science Foundation of China(No.32202221).
文摘Background:Previous studies found differences in the utilization of different carbon sources during biofilm formation by Bacillus cereus.Illumina HiSeq high-throughput sequencing technology was used to investigate the changes in gene transcript levels in Bacillus cereus biofilm bacteria under different carbon source conditions.Results:Compared with the control group,the number of differentially expressed genes in the glucose,maltose,lactose,and skim milksupplemented groups was 351,1136,133,and 487,respectively.The results showed that the pathways involved in the differentially expressed genes were mainly distributed in glycolysis and pentose phosphate pathway,tricarboxylic acid cycle,amino acid metabolism,and fatty acid metabolism.The gene expression of enzymes related to acetoin synthesis from pyruvate was mostly upregulated in the glucose-supplemented group.The gene expression of enzymes related to pyruvate synthesis of branched-chain amino acids in the maltose-supplemented group was mostly upregulated.In the lactose-supplemented group,the gene expression of acetoin biosynthesis from pyruvate was upregulated.Pyruvate production through glycolysis pathway increased in the skim milk-supplemented group,but the metabolic capacity of the tricarboxylic acid cycle did not change significantly.Conclusion:The content of pyruvate stored by Bacillus cereus biofilm bacteria through glycolysis or pentose phosphate pathway increased,but the carbon flux into the tricarboxylic acid cycle did not increase,which suggested that carbon fluxes in the extracellular polysaccharide synthesis pathway of the biofilm may be increased,resulting in increased biofilm biomass formation.
文摘Fermented foods play a very important role in Cambodian health and nutrition,as well as other developing countries where food preservation methods may be limited.SIENG,a Khmer fermented soybean product,naturally contains both beneficial and pathogenic microorganisms.Traditional fermentation that relies on natural microbial flora and environmental conditions results in variable product quality and can lead to spoilage.A starter culture such as Bacillus subtilis can ensure the safety and stability of the products.The objective of this study is to control the growth of Gram positive pathogens contaminated into traditional fermented soybean(SEING)by using antimicrobial Bacillus subtilis isolated from the same kind of food.Out of 120 SIENG samples,49 B.cereus strains were isolated,and 12 of B.cereus were positively synthesized compared with the lyophilized control enterotoxin.Two of these strains(BTM8-7 and BTM8-8)produced high levels of enterotoxin.We identified five Bacillus strains with the ability to fight against indicator pathogenic microorganisms.Among the five strains,B.CeM6-2 had the highest activity level against Lactobacillus plantrum ATCC 8014 and the largest diameter.B.CeM6-2 tolerated up to 20 h at 30℃ and 22 h at 37℃.In testing the strains with PK and PK-PMSF enzymes,bacteriocin produced by the strain B.CeM6PK untreated and B.CeM6-2PK-PMSF had a significantly stronger ability to suppress all the pathogenic indicators from 0 h to 47 h compared to the B.CeM6-2PK.Moreover,CeM6-2 outperformed the Miyagino strains,as it actively produced bacteriocin that fought against all four indicator strains of Gram positive and lactic acid groups,especially against Listeria monocytogenes,Streptococcus pyrogene,Leuconostoc mesenterids and L.plantarum,from 0 h-58 h and 0 h-40 h at 35℃.CeM6-2(1%)strain had the highest ability to fight against B.cereus at 24 h and at 34 h to 44 h incubation as well.CeM6-2(10:0 mL)and CeM6-2(9:1 mL)have the strongest ability to fight against B.cereus at room temperature(48 h and 72 h).The longer incubation and time at room temperature produce the highest level of bacteriocin.Thus,bacteriocins produced by B.CeM6-2 can be used as a preservative in food processing industries to avoid food spoilage even in higher temperatures and time.
文摘Garlic is a most important medicinal herb belonging to the family Liliaceae. Both its leaves and bulb are edible. The current study was based on evaluating the growth promoting potential of plant growth promoting rhizobacteria (PGPR) on garlic (Allium sativum L.) growth and biochemical contents. Garlic cloves were inoculated with 3 kinds of PGPRs, Pseudomonas putida (KX574857), Pseudomonas stutzeri (Kx574858) and Bacillus cereus (ATCC14579) at 10<sup>8</sup> cells/mL prior to sowing. Under natural conditions, plants were grown in the net house. The PGPR significantly enhanced % germination, leaf and root growth and their biomass also increased the diameter of bulb and fresh and dry weight. The flavonoids, phenolics, chlorophyll, protein and sugar content were also significantly increased due to PGPR inoculation. The Pseudomonas stutzeri was found most effective for producing longer leaves with moderate sugar, high flavonoids (129%) and phenolics (263%) in bulb over control (Tap). The Pseudomonas putida exhibited a maximum increase in bulb diameter and bulb biomass with maximum phenolics and flavonoid contents.
基金the National Natural Science Foundations of China(31772229 and 31660546)。
文摘Rhizosphere microbial communities play important roles in facilitating or inhibiting the establishment of exotic species.Since some invasive plants interact with soil microbial communities such as rhizosphere bacteria,changes triggered by rhizosphere bacteria may alter competitive interactions between exotic and native plants.This study compared the Bacillus cereus content in soils with different degrees of Ageratina adenophora invasion,and investigated the effects of A.adenophora allelochemicals on B.cereus growth and soil characteristics and the feedback effects of B.cereus on A.adenophora growth.Bacillus cereus content in the rhizosphere of A.adenophora increased with intensification of the invasion process,and newly invaded soil contained almost twice as much bacteria as noninvaded soil.When rhizosphere soil was added to the root exudates of A.adenophora,the contents of B.cereus were twice as much as the control,except on the first day.Certain soil parameters increased significantly,such as ammonium nitrogen(NH_(4)^(+)-N)and available phosphorus(AP),which were increased by 41 and 27%,respectively.Soil treatment with B.cereus promoted the degradation of two allelochemicals from the rhizosphere of A.adenophora,amorpha-4,7(11)-dien-8-one and 6-hydroxy-5-isopropy1-3,8-dimethyl-4 a,5,6,7,8,8 ahexahydraphthalen-2(1 H)-one,to varying degrees;and increased the germination rate by 50%,root length by 117%,shoot length by 48%and fresh weight by 81%for A.adenophora compared to those of untreated soil.Our results confirmed that the invasion of A.adenophora will promote an increase of B.cereus,a beneficial rhizosphere bacterium,which in turn induces a positive feedback effect on A.adenophora.
基金Pravara Institute of Medical Sciences, Loni (MS), India for the financial support
文摘The development of green experimental processes for the synthesis of nanoparticles is a need in the field of nanotechnology. The synthesis of silver nanoparticles was achieved using Bacillus cereus supernatant and1 m M silver nitrate. 100 m M glucose was found to quicken the rate of reaction of silver nanoparticles synthesis.UV-visible spectrophotometric analysis was carried out to assess the synthesis of silver nanoparticles. The synthesized silver nanoparticles were further characterized by using Nanoparticle Tracking Analyzer(NTA),Transmission Electron Microscope and Energy Dispersive X-ray spectra. These silver nanoparticles showed enhanced quorum quenching activity against Staphylococcus aureus biofilm and prevention of biofilm formation which can be seen under inverted microscope(40 X). The synergistic effect of silver nanoparticles along with antibiotics in biofilm quenching was found to be effective. In the near future, silver nanoparticles could be used in the treatment of infections caused by highly antibiotic resistant biofilm.
文摘BACKGROUND Phlegmonous gastritis(PG)is a rare bacterial infectious disease characterized by neutrophil-based purulent inflammation of the gastric wall.The most representative causative bacterium is Streptococcus pyogenes,followed by Staphylococcus,Pneumococcus and Enterococcus.Hepatic portal venous gas(HPVG)is considered a potentially fatal condition and is rarely associated with PG.CASE SUMMARY The white blood cell count of a 70-year-old woman with acute lymphocytic leukemia in complete remission dropped to 100/μL after consolidation chemotherapy.Her vital signs were consistent with septic shock.Venous blood culture revealed the presence of Bacillus cereus.Abdominal computed tomography(CT)and esophagogastroduodenoscopy(EGD)showed marked thickening of the gastric wall.As with the other findings,CT was suggestive of HPVG,and EGD showed pseudomembrane-like tissue covering the superficial mucosa.Histopathological examination of gastric biopsy specimens showed mostly necrotic tissue with lymphocytes rather than neutrophils.Culture of gastric specimens revealed the presence of Bacillus cereus.We finally diagnosed this case as PG with Bacillus cereus-induced sepsis and HPVG.This patient recovered successfully with conservative treatment,chiefly by using carbapenem antibiotics.CONCLUSION The histopathological finding of this gastric biopsy specimen should be called"neutropenic necrotizing gastritis".
文摘Antibacterial activity of methanol, n-hexane and water extracts of seeds and bark of Moringa oleifera and Moringa ovalifolia was conducted. The causative agents of common bacterial infections that are thought to cause water-borne diseases, namely, Escherichia coli, Enterococcus faecalis, and Bacillus cereus were chosen for the study. The paper-disc diffusion method was used with treatments arranged in a completely randomized design and replicated four times. The M. oleifera extracts showed more inhibitory effect than those of M. ovolifolia. The conventional antibiotic Ampicilin generally showed higher inhibitory effect than the extracts of both M. oleifera and M. ovalifolia. The inhibitory effect varied depending on the solvent used. The n-hexane extracts of both seeds and bark of M. ovalifolia and M. oleifera had almost the same inhibition activities (6 ± 1 mm mean inhibition zones) on B. cereus, E. coli and E. faecalis. The n-hexane extract generally gave lower antibacterial activities than those of the other solvents for seeds and back. The results of the study showed that M. oleifera and M. ovalifolia had a degree of antibacterial properties against the selected test organisms that cause water borne diseases.
基金supported by the National Natural Science Foundation of China(Nos.52000046,52100034,52170154,and 52070051)the Special Project of Guangxi Science and Technology Base and Talent(Nos.GuiKe AD20297009 and GuiKe AD20297007)the Middle-aged and Young Teachers’Basic Ability Promotion Project of Guangxi(Nos.2020KY05039 and 2021KY0221).
文摘Phytoextraction is a promising option for purifying hexavalent chromium(Cr(Ⅵ))-laden wastewater,but the long remediation period incurred by poor growth rate of Cr hyperaccumulators remains a primary hindrance to its large-scale application.In this study,we performed a hydroponic experiment to evaluate the feasibility of promoting the growth and phytoextraction efficiency of Cr hyperaccumulator Leersia hexandra Swartz(L.hexandra)by inoculating plant growth-promoting rhizobacteria(PGPR)Bacillus cereus(B.cereus).In batch tests,the Cr(Ⅵ)removal rates of L.hexandra and B.cereus co-culture were greater than the sum of their respective monocultures.This was likely due to the microbial reduction of Cr(Ⅵ)to Cr(Ⅲ),which is amiable to plant uptake.Besides,the PGPR factors of B.cereus,including indoleacetic acid(IAA)production,1-aminocyclopropane-1-carboxylic acid deamination(ACCd)activity,phosphate solubilization capacity,and siderophore production,were quantified.These PGPR factors helped explain the biomass augmentation,root elongation and enhanced Cr enrichment of the inoculated L.hexandra in pot experiments.Despite the increased Cr uptake,no aggravated oxidative damage to the cell membrane was observed in the inoculated L.hexandra.This was attributed to its capacity to confront the increased intracellular Cr stress by upregulating both the activities of antioxidative enzymes and expression of metal-binding proteins/peptides.Moreover,L.hexandra could always conserve the majority of Cr in the residual and oxalic integrated forms with low mobility and phytotoxicity,irrespective of the B.cereus inoculation.These results highlight the constructed Cr hyperaccumulatorrhizobacteria consortia as an effective candidate for decontaminating Cr(Ⅵ)-laden wastewater.
