Pseudomonas fragi and Pseudomonas lundensis have been reported as key spoilage bacteria in aerobicallystored chilled meat.However,the co-spoilage effect of these bacteria has not been effectively evaluated.This study ...Pseudomonas fragi and Pseudomonas lundensis have been reported as key spoilage bacteria in aerobicallystored chilled meat.However,the co-spoilage effect of these bacteria has not been effectively evaluated.This study evaluated the spoilage potential of P.fragi,P.lundensis and P.fragi+P.lundensis in vitro and in situ at 4℃.The results showed that P.fragi+P.lundensis performed the highest growth rate and displayed larger decomposition zone diameters on raw-pork juice agar(RJA)plates.P.fragi+P.lundensis inoculants exhibited the strongest proteolytic activity,which resulted in the highest values of trichloroacetic acid(TCA)-soluble peptides concentration,total volatile basic nitrogen(TVB-N)content and myofibril fragmentation index(MFI)in chilled pork.Moreover,the inoculated samples showed different pH and sensory changes.Notably,increased amounts of volatile organic compounds(VOCs),such as octanal,nonanal,2-nonanone,1-propanol,1-octanol,isopropyl acetate,and 2,6-dimethylpyazine,were observed in inoculated P.fragi+P.lundensis samples,hinting their potential use as spoilage markers for spoilage monitoring of co-cultures.This study would provide a deeper understanding of meat spoilage and serve as a reference for future studies to inhibit meat spoilage.展开更多
Oxytetracycline(OTC)is used extensively in animal husbandry and enters the soil in different forms,causing severe environmental pollution.Previous studies have shown that the genus Pseudomonas can potentially degrade ...Oxytetracycline(OTC)is used extensively in animal husbandry and enters the soil in different forms,causing severe environmental pollution.Previous studies have shown that the genus Pseudomonas can potentially degrade antibiotics in the soil environment.Environmental conditions,such as the initial concentration of antibiotics,incubation temperature and others,have significant impacts on the activity of antibiotic-degrading bacteria.However,few reports have clarified the environmental impacts on the effectiveness of Pseudomonas spp.In the present study,we investigated the effects of different initial concentrations of OTC and incubation temperatures,as well as soil sterilization,on OTC degradation by Pseudomonas strain T4.We also focused on the microbial degradation pathways of OTC,and variations in both antibiotic resistance genes(ARGs)and microbial communities with T4 functioning under optimal conditions.The results showed that the most effective degradation occurred under an initial OTC concentration of 2.5 mg kg^(-1)at 30℃in unsterilized soil spiked with T4.These conditions yielded an OTC degradation rate of 69.53%within 63 days.The putative degradation pathways of OTC in the presence of T4 included dehydration,demethylation,deamination,hydroxylation,oxidation and ring opening.Bacteroidetes,Proteobacteria and Acidobacteria played key roles in the biodegradation of OTC with T4 in the soil.The results also showed that tet(G)was the most frequently detected ARGs among the 13 common tetracycline ARGs that were investigated.The bacterial community shift observed in this study may provide new insights into the microbial degradation of OTC in soil.展开更多
Objective:To develop chitosan-silver nanoparticles targeting Pseudomonas aeruginosa biofilms and verify their antibacterial performance through animal experiments.Methods:Chitosan,silver nitrate,glacial acetic acid,an...Objective:To develop chitosan-silver nanoparticles targeting Pseudomonas aeruginosa biofilms and verify their antibacterial performance through animal experiments.Methods:Chitosan,silver nitrate,glacial acetic acid,and other chemical reagents were used to synthesize chitosan-silver nanoparticles.The characterization,minimum inhibitory concentration,and biofilm inhibition rate of the chitosan-silver nanoparticles were tested.A total of 40 SD rats were randomly divided into four groups.After routine adaptive feeding,the control group received intraperitoneal injection of normal saline;the model group received intraperitoneal injection of Pseudomonas aeruginosa suspension;the positive group received intraperitoneal injection of Pseudomonas aeruginosa suspension mixed with ampicillin at a volume ratio of 1∶1;the observation group received intraperitoneal injection of Pseudomonas aeruginosa suspension mixed with chitosan-silver nanoparticles(at minimum inhibitory concentration)at a volume ratio of 1∶1.Bacterial load,inflammatory factors,and liver and kidney function indicators in tissues were observed and compared among the four groups on the 3^(rd)day after treatment.Results:When the concentration of chitosansilver nanoparticles reached 8μg/mL or above,the OD value of the experimental wells was close to that of the control wells,indicating that 8μg/mL was the minimum inhibitory concentration of the chitosan-silver nanoparticles;at concentrations of 8μg/mL or above,the biofilm inhibition rate was greater than 80%.The bacterial load in the observation group was significantly lower than that in the model and positive groups(P<0.05).The expression levels of interleukin-6,interferon-γ,and tumor necrosis factor-αin the observation group were significantly lower than those in the model and positive groups(P<0.05).There were no statistically significant differences in alanine aminotransferase,aspartate aminotransferase,blood urea nitrogen,and creatinine levels among the four groups(P>0.05).Conclusion:The chitosan-silver nanoparticles targeting Pseudomonas aeruginosa biofilms constructed in this study exhibit good antibacterial effects against Pseudomonas aeruginosa and have good safety.展开更多
We assessed the quorum sensing(QS)inhibitory impact of sesamol against the foodborne bacterium Pseudomonas aeruginosa.At concentrations ranging from 50 to 200μg/mL,sesamol significantly inhibited the production of vi...We assessed the quorum sensing(QS)inhibitory impact of sesamol against the foodborne bacterium Pseudomonas aeruginosa.At concentrations ranging from 50 to 200μg/mL,sesamol significantly inhibited the production of virulence factors such as protease,elastase,pyocyanin,rhamnolipid,and chemotaxis,and improved the susceptibility of bacterial and biofilm cells to colistin.Integrated transcriptomics,metabolomics,and docking analyses indicated that exposure to sesamol destroyed the QS system and down-regulated the expressions of genes encoding virulence and antioxidant enzymes.The down-regulation of genes encoding antioxidant enzymes intensified oxidative stress,as demonstrated by the enhancement of reactive oxygen species and H_(2)O_(2).The enhanced oxidative stress changed the components of the cell membrane,improved its permeability,and ultimately enhanced the susceptibility of bacterial and biofilm cells to colistin.Moreover,exposure to sesamol also led to the disorder of amino acid metabolism and energy metabolism,eventually attenuating the pathogenicity of P.aeruginosa.These findings indicated that sesamol can function as a potent anti-virulence agent to defend against food spoilage caused by P.aeruginosa.展开更多
Small RNAs(sRNAs)are a class of molecules capable of perceiving environmental changes and exerting posttranscriptional regulation over target gene expression,thereby influencing bacterial virulence and host immune res...Small RNAs(sRNAs)are a class of molecules capable of perceiving environmental changes and exerting posttranscriptional regulation over target gene expression,thereby influencing bacterial virulence and host immune responses.Pseudomonas plecoglossicida is a pathogenic bacterium that poses a significant threat to aquatic animal health.However,the regulatory mechanisms of sRNAs in P.plecoglossicida remain unclear.This study focused on sRNA113,previously identified as a potential regulator of the fliP gene,a key component of the lateral flagellar type III secretion system.To investigate the effects of sRNA113on P.plecoglossicida virulence,as well as its role in regulating pathogenic processes and host immune responses,mutant strains lacking this sRNA were generated and analyzed.Deletion of sRNA113 resulted in the up-regulation of lateral flagellar type III secretion system-related genes in P.plecoglossicida,which enhanced bacterial swarming motility,biofilm formation,and chemotaxis ability in vitro.In vivo infection experiments with pearl gentian grouper revealed that sRNA113 deletion enhanced the pathogenicity of P.plecoglossicida.This heightened virulence was attributed to the up-regulation of genes associated with the lateral flagellar type III secretion system,resulting in higher bacterial loads within host tissues.This amplification of pathogenic activity intensified tissue damage,disrupted immune responses,and impaired the ability of the host to clear infection,ultimately leading to mortality.These findings underscore the critical role of sRNA113 in regulating the virulence of P.plecoglossicida and its interaction with host immune defenses.This study provides a foundation for further exploration of sRNAmediated mechanisms in bacterial pathogenesis and hostpathogen interactions,contributing to a deeper understanding of virulence regulation and immune evasion in aquatic pathogens.展开更多
Pseudomonas aeruginosa is an opportunistic pathogen widely distributed in the natural environment,which can cause a variety of infections,especially in people with low immunity and high pathogenicity.In recent years,s...Pseudomonas aeruginosa is an opportunistic pathogen widely distributed in the natural environment,which can cause a variety of infections,especially in people with low immunity and high pathogenicity.In recent years,significant progress has been made in the detection technology of Pseudomonas aeruginosa,covering traditional methods,molecular biology techniques,immunological methods and automated detection systems.Traditional methods such as the national standard method and the filter membrane method are easy to operate,but have the problems of long time consuming and limited sensitivity.Molecular biological techniques(such as PCR,gene cloning)and immunological methods(such as ELISA,colloidal gold immunochromatography)have significantly improved the sensitivity and specificity of detection,but they require high equipment and technology,and are expensive.Automated detection systems,such as VITEK 2 Compact and AutoMS 1000 mass spectrometry identification system,are excellent in improving detection efficiency and accuracy,but their high cost and complex operation process limit their wide application.In addition,the resistance of Pseudomonas aeruginosa to bacteriostatic agents further increases the difficulty of detection.In this paper,the development and application of immunological detection technology,molecular biological technology and immunological technology of Pseudomonas aeruginosa were reviewed,and the principles,advantages,disadvantages and research progress of various detection technologies of Pseudomonas aeruginosa were described,and the future development trend was prospected,in order to provide reference for the optimization and development of detection methods of Pseudomonas aeruginosa.展开更多
The isolation of bacteria from the rhizosphere soil of different plants and locations in Diwaniyah Governorate and their diagnosis by two methods.Isolation and routine molecular diagnosis revealed ten bacterial isolat...The isolation of bacteria from the rhizosphere soil of different plants and locations in Diwaniyah Governorate and their diagnosis by two methods.Isolation and routine molecular diagnosis revealed ten bacterial isolates with the attributes of P.fluorescens out of fifteen local isolates that are represented by the following codes and sequences(P.f9,P.f8,P.f6,P.f5,P.f4,P.f2,P.f1,P.f14,P.f13,P.f11).Results also confirmed the diagnosis of bacterial isolates by biochemical and molecular tests using a specialized primer to amplify the bp698 region of the 16S ribosomal RNA gene,approved by Macrogen/Korea.The test efficiency in dissolving solid phosphate by P.fluorescens bacteria showed that the most effective is the(P.f1)isolate,giving the highest score effectiveness in mineral phosphate dissolution by the diameter of the clear zone around the colony,which was effective in phosphate dissolution up to 6.95 mm.The efficiency of the Nitrogen Fixation Test showed that the isolate(P.f5)scored the highest nitrogen-fixing efficiency amount with a value of 6.81 mg L^(-1).The quantitative amount of the hormone for each of Auxins,Cytokinins,and Gibberellins was assayed;the results with isolate(P.f1)for IAA(Auxins)gave a concentration up to 28.6μg ml^(-1),which was the most,while the production of GA3 by isolate(P.f1)gave the maximum value of 36.7μg ml^(-1),and for synthesis of the hormone of Cytokinins represented by isolate(P.f2),the highest value in the production of Cytokinins hormone was recorded at 26.3μg ml^(-1).展开更多
Objective Pseudomonas aeruginosa(P.aeruginosa)is a prevalent pathogenic bacterium involved in meningitis;however,the virulence factors contributing to this disease remain poorly understood.Methods The virulence of the...Objective Pseudomonas aeruginosa(P.aeruginosa)is a prevalent pathogenic bacterium involved in meningitis;however,the virulence factors contributing to this disease remain poorly understood.Methods The virulence of the P.aeruginosa A584,isolated from meningitis samples,was evaluated by constructing in vitro blood-brain barrier and in vivo systemic infection models.qPCR,whole-genome sequencing,and drug efflux assays of A584 were performed to analyze the virulence factors.Results Genomic sequencing showed that A584 formed a phylogenetic cluster with the reference strains NY7610,DDRC3,Pa58,and Pa124.Its genome includes abundant virulence factors,such as hemolysin,the Type IV secretion system,and pyoverdine.A584 is a multidrug-resistant strain,and its wide-spectrum resistance is associated with enhanced drug efflux.Moreover,this strain caused significantly more severe damage to the blood-brain barrier than the standard strain,PAO1.qPCR assays further revealed the downregulation of the blood-brain barrier-associated proteins Claudin-5 and Occludin by A584.During systemic infection,A584 exhibited a higher capacity of brain colonization than PAO1(37.1×10^(6) CFU/g brain versus 2.5×10^(6) CFU/g brain),leading to higher levels of the proinflammatory factors IL-1βand TNF-α.Conclusion This study sheds light on the virulence factors of P.aeruginosa involved in meningitis.展开更多
Background:Corneal scarring following bacterial keratitis,particularly from Pseudomonas infections,poses significant challenges in ophthalmic care.Current treatments often fall short in effectively reducing corneal ha...Background:Corneal scarring following bacterial keratitis,particularly from Pseudomonas infections,poses significant challenges in ophthalmic care.Current treatments often fall short in effectively reducing corneal haze and restoring vision.To our knowledge,this is the first report documenting the use of topical losartan,an angiotensin II receptor antagonist known to inhibit the transforming growth factor-β(TGF-β)pathway,for treating corneal haze resulting from bacterial keratitis.Case Description:A 30-year-old male presented with a persistent corneal scar in his right eye,178 days post-Pseudomonas keratitis.Despite a prolonged course of topical corticosteroids,his best-corrected visual acuity(BCVA)stabilized at 20/40 with a hybrid contact lens over a 2-month period.Given the lack of improvement,we initiated treatment with topical losartan at a concentration of 0.8 mg/mL,administered six times daily.After 4 months of therapy,the patient’s BCVA improved to 20/25.Slit-lamp examination and corneal tomography revealed a significant reduction in corneal haze,indicating a positive response to the treatment.Conclusions:This case suggests that topical losartan may be a promising therapeutic option for reducing corneal opacity following bacterial keratitis by inhibiting the TGF-βpathway.However,further clinical studies are necessary to confirm its efficacy and safety in broader patient populations.展开更多
Large yellow croaker(Larimichthys crocea)is an economically important fish,with the annual production ranking second among maricultured fish in China.Outbreaks of visceral white nodules disease caused by Pseudomonas p...Large yellow croaker(Larimichthys crocea)is an economically important fish,with the annual production ranking second among maricultured fish in China.Outbreaks of visceral white nodules disease caused by Pseudomonas plecoglossicida have led to substantial economic losses for the L.crocea aquaculture industry.However,L.crocea defense strategies against P.plecoglossicida infection,especially the role of microRNAs(miRNAs)in the defense against P.plecoglossicida,are poorly understood.Here,we analyzed changes in the mRNA and miRNA expression profiles in the spleen of L.crocea at 96 h post-infection and explored its defensive strategies.Principal component analysis(PCA)showed that P.plecoglossicida infection brought about a profound remodeling of both the miRNA and mRNA profiles.Enrichment analysis showed that the inflammatory response(IL-17 signaling pathway,chemokines and chemokine receptor pathway),ATP synthesis(TCA cycle and oxidative phosphorylation),apoptosis and necroptosis(TNF signaling pathway),and proteolysis(proteasome pathway)were enriched and upregulated by P.plecoglossicida.Thus,P.plecoglossicida infection activated the inflammatory response,stimulated ATP synthesis,and accelerated apoptosis and necroptosis,and promoted proteasome-mediated protein degradation.Additionally,integrated analysis identified 568 miRNA-mRNA pairs.KEGG enrichment analysis of the miRNA targets showed that the enriched pathways included cytokine-cytokine receptor interaction,the chemokine signaling pathway,the C-type lectin receptor signaling pathway,and apoptosis.Integrated analysis identified 14 miRNAs which targeted 44 immune-related genes.Altogether,our results revealed not only the role of the inflammatory response,energy metabolism,apoptosis and necroptosis,and the proteasome pathway in L.crocea defense against P.plecoglossicida infection,but also the regulatory networks of miRNAs associated with host defense against P.plecoglossicida.展开更多
Pseudomonas syringae pv.actinidiae(Psa)causes destructive kiwifruit bacterial canker by invading vascular tissues across multiple plant organs.However,the cellular mechanism underlying its systemic transmission and ce...Pseudomonas syringae pv.actinidiae(Psa)causes destructive kiwifruit bacterial canker by invading vascular tissues across multiple plant organs.However,the cellular mechanism underlying its systemic transmission and cell-to-cell movement within these specialized vascular conduits remains unclear.In this study,a Psa-GFP strain and various microscopic techniques were used to investigate the interaction between kiwifruit and Psa.Our results reveal that Psa strategically exploits host vascular conduits for systemic movement,with the xylem vessel being the predominant avenue.In the phloem,Psa exhibits adaptive alteration in bacterial shape to traverse sieve pores,facilitating its systemic spread along sieve tubes and inducing phloem necrosis.Within the xylem,Psa breaches pit membranes to migrate between adjacent vessels.Furthermore,phloem fibers act as an initial barrier at the early stages of infection,delaying Psa's entry into vascular tissues during its journey to the xylem.Additionally,at the junctions of stem-stem or stem-leaf,branch trace or leaf trace mediates the bacterial organ-to-organ translocation,thus facilitating the systemic progression of disease.In conclusion,our findings shed light on the cellular mechanism employed by Psa to exploit the woody plant's vascular network for infection,thereby enhancing a better understanding of the biology of this poorly defined bacterium.These insights carry implications for the pathogenesis of Psa and other vascular pathogens,offering theoretical guidance for effective control strategies.展开更多
The Cd-tolerant and sodium alginate(SA)-synthesizing Pseudomonas putida XMS-1was characterized for Cd immobilization in solution.Additionally,the XMS-1 mutant constructed by deleting SA-synthesizing regulatory gene al...The Cd-tolerant and sodium alginate(SA)-synthesizing Pseudomonas putida XMS-1was characterized for Cd immobilization in solution.Additionally,the XMS-1 mutant constructed by deleting SA-synthesizing regulatory gene algB(△algB)were characterized for their roles in Cd uptake in Chinese chive in the Cd-contaminated soil.Between 12 and 48 h of incubation,the XMS-1△algBmutant significantly reduced solution Cd concentrations by 81%compared with the control but increased the Cd concentrations by 36%compared with XMS-1.After 48 h of incubation,the XMS-1△algB mutant significantly increased the Cd concentration by 36%and decreased the expolysaccharide(EPS)and SA concentrations by 30%-32%and cell surface-adsorbed Cd content by 24%in the Cd-containing medium,compared with XMS-1.The XMS-1△algB mutant significantly increased the root and leaf Cd contents of Chinese chive by 15%-50%and exchangeable Cd content by 17%and decreased the Fe-Mn oxideand organic matter-bound Cd contents by 17%-23%,compared with XMS-1.Furthermore,the XMS-1△algBmutant significantly decreased the EPS content by 33%,copies of algD gene involved in EPS production by 7.7-fold,and the interactions between the amino,hydroxyl,and carbonyl groups and Cd in the Cd-contaminated soil,compared with XMS-1.These results suggested that algB promoted XMS-1-mediated Cd-stabilizing related gene abundance and interactions between soil and Cd and decreased Cd uptake in Chinese chive.These findings may provide an effective and eco-friendly way using SA-producing bacteria for safe production of vegetables in the Cd-polluted soil.展开更多
Nicotine,also known as nicotinic norephedrine,is one of the main alkaloids present in tobacco plants.In recent years,due to the increase in tobacco production and smoking population,the environmental and health issues...Nicotine,also known as nicotinic norephedrine,is one of the main alkaloids present in tobacco plants.In recent years,due to the increase in tobacco production and smoking population,the environmental and health issues caused by nicotine have become increasingly severe.Traditional methods have proven ineffective in efficiently degrading residual nicotine.To address this issue,scientists both domestically and internationally have turned to biodegradation methods to tackle the environmental and health problems caused by residual nicotine.In this study,an enrichment method was used to screen bacteria with nicotine-degrading capabilities from the soil of tobacco planting sites at the Tobacco Research Institute of Heilongjiang in Bin County,Harbin City.Through phenotypic observations and 16S rDNA identification,a bacterial strain identified as Pseudomonas hunanensis MGJ-2 was isolated,capable of utilizing nicotine as a carbon and nitrogen source for growth.High-performance liquid chromatography(HPLC)-1 analysis revealed that within 25 h,strain MGJ-2 could degrade nicotine 500 mg·L^(-1) with an efficiency exceeding 99.9%.Strain MGJ-2 was applied to tobacco,and after 15 days of incubation and fermentation,it degraded 10.57%of nicotine in tobacco.Overall,the discovery of strain MGJ-2 enriched the resources of nicotine-degrading strains.Its remarkable biodegradation performance held immense potential for future biodegradation of nicotine in tobacco.展开更多
基金funded by the National Natural Science Foundation of China(32372404)the National Key Research and Development Program of China(2021YFD2100802-02)。
文摘Pseudomonas fragi and Pseudomonas lundensis have been reported as key spoilage bacteria in aerobicallystored chilled meat.However,the co-spoilage effect of these bacteria has not been effectively evaluated.This study evaluated the spoilage potential of P.fragi,P.lundensis and P.fragi+P.lundensis in vitro and in situ at 4℃.The results showed that P.fragi+P.lundensis performed the highest growth rate and displayed larger decomposition zone diameters on raw-pork juice agar(RJA)plates.P.fragi+P.lundensis inoculants exhibited the strongest proteolytic activity,which resulted in the highest values of trichloroacetic acid(TCA)-soluble peptides concentration,total volatile basic nitrogen(TVB-N)content and myofibril fragmentation index(MFI)in chilled pork.Moreover,the inoculated samples showed different pH and sensory changes.Notably,increased amounts of volatile organic compounds(VOCs),such as octanal,nonanal,2-nonanone,1-propanol,1-octanol,isopropyl acetate,and 2,6-dimethylpyazine,were observed in inoculated P.fragi+P.lundensis samples,hinting their potential use as spoilage markers for spoilage monitoring of co-cultures.This study would provide a deeper understanding of meat spoilage and serve as a reference for future studies to inhibit meat spoilage.
基金funded by the earmarked fund for China Agriculture Research System(CARS-29-zp-10)。
文摘Oxytetracycline(OTC)is used extensively in animal husbandry and enters the soil in different forms,causing severe environmental pollution.Previous studies have shown that the genus Pseudomonas can potentially degrade antibiotics in the soil environment.Environmental conditions,such as the initial concentration of antibiotics,incubation temperature and others,have significant impacts on the activity of antibiotic-degrading bacteria.However,few reports have clarified the environmental impacts on the effectiveness of Pseudomonas spp.In the present study,we investigated the effects of different initial concentrations of OTC and incubation temperatures,as well as soil sterilization,on OTC degradation by Pseudomonas strain T4.We also focused on the microbial degradation pathways of OTC,and variations in both antibiotic resistance genes(ARGs)and microbial communities with T4 functioning under optimal conditions.The results showed that the most effective degradation occurred under an initial OTC concentration of 2.5 mg kg^(-1)at 30℃in unsterilized soil spiked with T4.These conditions yielded an OTC degradation rate of 69.53%within 63 days.The putative degradation pathways of OTC in the presence of T4 included dehydration,demethylation,deamination,hydroxylation,oxidation and ring opening.Bacteroidetes,Proteobacteria and Acidobacteria played key roles in the biodegradation of OTC with T4 in the soil.The results also showed that tet(G)was the most frequently detected ARGs among the 13 common tetracycline ARGs that were investigated.The bacterial community shift observed in this study may provide new insights into the microbial degradation of OTC in soil.
文摘Objective:To develop chitosan-silver nanoparticles targeting Pseudomonas aeruginosa biofilms and verify their antibacterial performance through animal experiments.Methods:Chitosan,silver nitrate,glacial acetic acid,and other chemical reagents were used to synthesize chitosan-silver nanoparticles.The characterization,minimum inhibitory concentration,and biofilm inhibition rate of the chitosan-silver nanoparticles were tested.A total of 40 SD rats were randomly divided into four groups.After routine adaptive feeding,the control group received intraperitoneal injection of normal saline;the model group received intraperitoneal injection of Pseudomonas aeruginosa suspension;the positive group received intraperitoneal injection of Pseudomonas aeruginosa suspension mixed with ampicillin at a volume ratio of 1∶1;the observation group received intraperitoneal injection of Pseudomonas aeruginosa suspension mixed with chitosan-silver nanoparticles(at minimum inhibitory concentration)at a volume ratio of 1∶1.Bacterial load,inflammatory factors,and liver and kidney function indicators in tissues were observed and compared among the four groups on the 3^(rd)day after treatment.Results:When the concentration of chitosansilver nanoparticles reached 8μg/mL or above,the OD value of the experimental wells was close to that of the control wells,indicating that 8μg/mL was the minimum inhibitory concentration of the chitosan-silver nanoparticles;at concentrations of 8μg/mL or above,the biofilm inhibition rate was greater than 80%.The bacterial load in the observation group was significantly lower than that in the model and positive groups(P<0.05).The expression levels of interleukin-6,interferon-γ,and tumor necrosis factor-αin the observation group were significantly lower than those in the model and positive groups(P<0.05).There were no statistically significant differences in alanine aminotransferase,aspartate aminotransferase,blood urea nitrogen,and creatinine levels among the four groups(P>0.05).Conclusion:The chitosan-silver nanoparticles targeting Pseudomonas aeruginosa biofilms constructed in this study exhibit good antibacterial effects against Pseudomonas aeruginosa and have good safety.
基金supported by grants from the National Natural Science Foundation of China(32000091)General Projects of Natural Science Research in Universities of Jiangsu Province(20KJB180019)Jiangsu Youth Talent Promotion Project(TJ-2021-066)。
文摘We assessed the quorum sensing(QS)inhibitory impact of sesamol against the foodborne bacterium Pseudomonas aeruginosa.At concentrations ranging from 50 to 200μg/mL,sesamol significantly inhibited the production of virulence factors such as protease,elastase,pyocyanin,rhamnolipid,and chemotaxis,and improved the susceptibility of bacterial and biofilm cells to colistin.Integrated transcriptomics,metabolomics,and docking analyses indicated that exposure to sesamol destroyed the QS system and down-regulated the expressions of genes encoding virulence and antioxidant enzymes.The down-regulation of genes encoding antioxidant enzymes intensified oxidative stress,as demonstrated by the enhancement of reactive oxygen species and H_(2)O_(2).The enhanced oxidative stress changed the components of the cell membrane,improved its permeability,and ultimately enhanced the susceptibility of bacterial and biofilm cells to colistin.Moreover,exposure to sesamol also led to the disorder of amino acid metabolism and energy metabolism,eventually attenuating the pathogenicity of P.aeruginosa.These findings indicated that sesamol can function as a potent anti-virulence agent to defend against food spoilage caused by P.aeruginosa.
基金supported by the National Natural Science Foundation of China (32373181)National Key Research and Development Program (2023YFD2400700)+2 种基金Science and Technology Plan Project of Fujian Province (2022L3059)High-quality Development of Marine and Fishery Industry Special Fund Project of Fujian Province (FJHYF-L-2023-5)Open Fund of Fujian Province Key Laboratory of Special Aquatic Formula Feed (TMKJZ2302)。
文摘Small RNAs(sRNAs)are a class of molecules capable of perceiving environmental changes and exerting posttranscriptional regulation over target gene expression,thereby influencing bacterial virulence and host immune responses.Pseudomonas plecoglossicida is a pathogenic bacterium that poses a significant threat to aquatic animal health.However,the regulatory mechanisms of sRNAs in P.plecoglossicida remain unclear.This study focused on sRNA113,previously identified as a potential regulator of the fliP gene,a key component of the lateral flagellar type III secretion system.To investigate the effects of sRNA113on P.plecoglossicida virulence,as well as its role in regulating pathogenic processes and host immune responses,mutant strains lacking this sRNA were generated and analyzed.Deletion of sRNA113 resulted in the up-regulation of lateral flagellar type III secretion system-related genes in P.plecoglossicida,which enhanced bacterial swarming motility,biofilm formation,and chemotaxis ability in vitro.In vivo infection experiments with pearl gentian grouper revealed that sRNA113 deletion enhanced the pathogenicity of P.plecoglossicida.This heightened virulence was attributed to the up-regulation of genes associated with the lateral flagellar type III secretion system,resulting in higher bacterial loads within host tissues.This amplification of pathogenic activity intensified tissue damage,disrupted immune responses,and impaired the ability of the host to clear infection,ultimately leading to mortality.These findings underscore the critical role of sRNA113 in regulating the virulence of P.plecoglossicida and its interaction with host immune defenses.This study provides a foundation for further exploration of sRNAmediated mechanisms in bacterial pathogenesis and hostpathogen interactions,contributing to a deeper understanding of virulence regulation and immune evasion in aquatic pathogens.
基金College Students’Innovation and Entrepreneurship Training Program Project(X202511049398)College Students’Innovation and Entrepreneurship Training Program Project(X202511049201)+1 种基金College Students’Innovation and Entrepreneurship Training Program Project(D202504071303298456)Hainan Vocational University of Science and Technology University-Level Scientific Research Funding Project(HKKY2024-87).
文摘Pseudomonas aeruginosa is an opportunistic pathogen widely distributed in the natural environment,which can cause a variety of infections,especially in people with low immunity and high pathogenicity.In recent years,significant progress has been made in the detection technology of Pseudomonas aeruginosa,covering traditional methods,molecular biology techniques,immunological methods and automated detection systems.Traditional methods such as the national standard method and the filter membrane method are easy to operate,but have the problems of long time consuming and limited sensitivity.Molecular biological techniques(such as PCR,gene cloning)and immunological methods(such as ELISA,colloidal gold immunochromatography)have significantly improved the sensitivity and specificity of detection,but they require high equipment and technology,and are expensive.Automated detection systems,such as VITEK 2 Compact and AutoMS 1000 mass spectrometry identification system,are excellent in improving detection efficiency and accuracy,but their high cost and complex operation process limit their wide application.In addition,the resistance of Pseudomonas aeruginosa to bacteriostatic agents further increases the difficulty of detection.In this paper,the development and application of immunological detection technology,molecular biological technology and immunological technology of Pseudomonas aeruginosa were reviewed,and the principles,advantages,disadvantages and research progress of various detection technologies of Pseudomonas aeruginosa were described,and the future development trend was prospected,in order to provide reference for the optimization and development of detection methods of Pseudomonas aeruginosa.
文摘The isolation of bacteria from the rhizosphere soil of different plants and locations in Diwaniyah Governorate and their diagnosis by two methods.Isolation and routine molecular diagnosis revealed ten bacterial isolates with the attributes of P.fluorescens out of fifteen local isolates that are represented by the following codes and sequences(P.f9,P.f8,P.f6,P.f5,P.f4,P.f2,P.f1,P.f14,P.f13,P.f11).Results also confirmed the diagnosis of bacterial isolates by biochemical and molecular tests using a specialized primer to amplify the bp698 region of the 16S ribosomal RNA gene,approved by Macrogen/Korea.The test efficiency in dissolving solid phosphate by P.fluorescens bacteria showed that the most effective is the(P.f1)isolate,giving the highest score effectiveness in mineral phosphate dissolution by the diameter of the clear zone around the colony,which was effective in phosphate dissolution up to 6.95 mm.The efficiency of the Nitrogen Fixation Test showed that the isolate(P.f5)scored the highest nitrogen-fixing efficiency amount with a value of 6.81 mg L^(-1).The quantitative amount of the hormone for each of Auxins,Cytokinins,and Gibberellins was assayed;the results with isolate(P.f1)for IAA(Auxins)gave a concentration up to 28.6μg ml^(-1),which was the most,while the production of GA3 by isolate(P.f1)gave the maximum value of 36.7μg ml^(-1),and for synthesis of the hormone of Cytokinins represented by isolate(P.f2),the highest value in the production of Cytokinins hormone was recorded at 26.3μg ml^(-1).
基金supported by National Natural Science Foundation of China,China(32170102)Natural Science Foundation of Tianjin(21JCYBJC01420)the Fundamental Research Funds for the Central Universities(63233050)。
文摘Objective Pseudomonas aeruginosa(P.aeruginosa)is a prevalent pathogenic bacterium involved in meningitis;however,the virulence factors contributing to this disease remain poorly understood.Methods The virulence of the P.aeruginosa A584,isolated from meningitis samples,was evaluated by constructing in vitro blood-brain barrier and in vivo systemic infection models.qPCR,whole-genome sequencing,and drug efflux assays of A584 were performed to analyze the virulence factors.Results Genomic sequencing showed that A584 formed a phylogenetic cluster with the reference strains NY7610,DDRC3,Pa58,and Pa124.Its genome includes abundant virulence factors,such as hemolysin,the Type IV secretion system,and pyoverdine.A584 is a multidrug-resistant strain,and its wide-spectrum resistance is associated with enhanced drug efflux.Moreover,this strain caused significantly more severe damage to the blood-brain barrier than the standard strain,PAO1.qPCR assays further revealed the downregulation of the blood-brain barrier-associated proteins Claudin-5 and Occludin by A584.During systemic infection,A584 exhibited a higher capacity of brain colonization than PAO1(37.1×10^(6) CFU/g brain versus 2.5×10^(6) CFU/g brain),leading to higher levels of the proinflammatory factors IL-1βand TNF-α.Conclusion This study sheds light on the virulence factors of P.aeruginosa involved in meningitis.
文摘Background:Corneal scarring following bacterial keratitis,particularly from Pseudomonas infections,poses significant challenges in ophthalmic care.Current treatments often fall short in effectively reducing corneal haze and restoring vision.To our knowledge,this is the first report documenting the use of topical losartan,an angiotensin II receptor antagonist known to inhibit the transforming growth factor-β(TGF-β)pathway,for treating corneal haze resulting from bacterial keratitis.Case Description:A 30-year-old male presented with a persistent corneal scar in his right eye,178 days post-Pseudomonas keratitis.Despite a prolonged course of topical corticosteroids,his best-corrected visual acuity(BCVA)stabilized at 20/40 with a hybrid contact lens over a 2-month period.Given the lack of improvement,we initiated treatment with topical losartan at a concentration of 0.8 mg/mL,administered six times daily.After 4 months of therapy,the patient’s BCVA improved to 20/25.Slit-lamp examination and corneal tomography revealed a significant reduction in corneal haze,indicating a positive response to the treatment.Conclusions:This case suggests that topical losartan may be a promising therapeutic option for reducing corneal opacity following bacterial keratitis by inhibiting the TGF-βpathway.However,further clinical studies are necessary to confirm its efficacy and safety in broader patient populations.
基金The National Key Research and Development Program of China under contract No.2022YFD2401002the National Natural Science Foundation of China under contract No.32102784+1 种基金the Natural Science Foundation of Fujian Province under contract No.2022J01211209the Fund of the Institute of Oceanology of Fuzhou under contract No.2021F02.
文摘Large yellow croaker(Larimichthys crocea)is an economically important fish,with the annual production ranking second among maricultured fish in China.Outbreaks of visceral white nodules disease caused by Pseudomonas plecoglossicida have led to substantial economic losses for the L.crocea aquaculture industry.However,L.crocea defense strategies against P.plecoglossicida infection,especially the role of microRNAs(miRNAs)in the defense against P.plecoglossicida,are poorly understood.Here,we analyzed changes in the mRNA and miRNA expression profiles in the spleen of L.crocea at 96 h post-infection and explored its defensive strategies.Principal component analysis(PCA)showed that P.plecoglossicida infection brought about a profound remodeling of both the miRNA and mRNA profiles.Enrichment analysis showed that the inflammatory response(IL-17 signaling pathway,chemokines and chemokine receptor pathway),ATP synthesis(TCA cycle and oxidative phosphorylation),apoptosis and necroptosis(TNF signaling pathway),and proteolysis(proteasome pathway)were enriched and upregulated by P.plecoglossicida.Thus,P.plecoglossicida infection activated the inflammatory response,stimulated ATP synthesis,and accelerated apoptosis and necroptosis,and promoted proteasome-mediated protein degradation.Additionally,integrated analysis identified 568 miRNA-mRNA pairs.KEGG enrichment analysis of the miRNA targets showed that the enriched pathways included cytokine-cytokine receptor interaction,the chemokine signaling pathway,the C-type lectin receptor signaling pathway,and apoptosis.Integrated analysis identified 14 miRNAs which targeted 44 immune-related genes.Altogether,our results revealed not only the role of the inflammatory response,energy metabolism,apoptosis and necroptosis,and the proteasome pathway in L.crocea defense against P.plecoglossicida infection,but also the regulatory networks of miRNAs associated with host defense against P.plecoglossicida.
基金supported by grants from the National Key Research and Development Program of China(Grant No.2022YFD1400200)the Special Support Plan for High-Level Talent of Shaanxi Provincethe First-Class Universities and Academic Programs of Northwest A&F University.
文摘Pseudomonas syringae pv.actinidiae(Psa)causes destructive kiwifruit bacterial canker by invading vascular tissues across multiple plant organs.However,the cellular mechanism underlying its systemic transmission and cell-to-cell movement within these specialized vascular conduits remains unclear.In this study,a Psa-GFP strain and various microscopic techniques were used to investigate the interaction between kiwifruit and Psa.Our results reveal that Psa strategically exploits host vascular conduits for systemic movement,with the xylem vessel being the predominant avenue.In the phloem,Psa exhibits adaptive alteration in bacterial shape to traverse sieve pores,facilitating its systemic spread along sieve tubes and inducing phloem necrosis.Within the xylem,Psa breaches pit membranes to migrate between adjacent vessels.Furthermore,phloem fibers act as an initial barrier at the early stages of infection,delaying Psa's entry into vascular tissues during its journey to the xylem.Additionally,at the junctions of stem-stem or stem-leaf,branch trace or leaf trace mediates the bacterial organ-to-organ translocation,thus facilitating the systemic progression of disease.In conclusion,our findings shed light on the cellular mechanism employed by Psa to exploit the woody plant's vascular network for infection,thereby enhancing a better understanding of the biology of this poorly defined bacterium.These insights carry implications for the pathogenesis of Psa and other vascular pathogens,offering theoretical guidance for effective control strategies.
基金supported by the National Natural Science Foundation of China(No.41977199).
文摘The Cd-tolerant and sodium alginate(SA)-synthesizing Pseudomonas putida XMS-1was characterized for Cd immobilization in solution.Additionally,the XMS-1 mutant constructed by deleting SA-synthesizing regulatory gene algB(△algB)were characterized for their roles in Cd uptake in Chinese chive in the Cd-contaminated soil.Between 12 and 48 h of incubation,the XMS-1△algBmutant significantly reduced solution Cd concentrations by 81%compared with the control but increased the Cd concentrations by 36%compared with XMS-1.After 48 h of incubation,the XMS-1△algB mutant significantly increased the Cd concentration by 36%and decreased the expolysaccharide(EPS)and SA concentrations by 30%-32%and cell surface-adsorbed Cd content by 24%in the Cd-containing medium,compared with XMS-1.The XMS-1△algB mutant significantly increased the root and leaf Cd contents of Chinese chive by 15%-50%and exchangeable Cd content by 17%and decreased the Fe-Mn oxideand organic matter-bound Cd contents by 17%-23%,compared with XMS-1.Furthermore,the XMS-1△algBmutant significantly decreased the EPS content by 33%,copies of algD gene involved in EPS production by 7.7-fold,and the interactions between the amino,hydroxyl,and carbonyl groups and Cd in the Cd-contaminated soil,compared with XMS-1.These results suggested that algB promoted XMS-1-mediated Cd-stabilizing related gene abundance and interactions between soil and Cd and decreased Cd uptake in Chinese chive.These findings may provide an effective and eco-friendly way using SA-producing bacteria for safe production of vegetables in the Cd-polluted soil.
基金Supported by the Research on Biofermentation Technology of Domestic Cigar Tobacco(202115010534-JS-178)(2021)。
文摘Nicotine,also known as nicotinic norephedrine,is one of the main alkaloids present in tobacco plants.In recent years,due to the increase in tobacco production and smoking population,the environmental and health issues caused by nicotine have become increasingly severe.Traditional methods have proven ineffective in efficiently degrading residual nicotine.To address this issue,scientists both domestically and internationally have turned to biodegradation methods to tackle the environmental and health problems caused by residual nicotine.In this study,an enrichment method was used to screen bacteria with nicotine-degrading capabilities from the soil of tobacco planting sites at the Tobacco Research Institute of Heilongjiang in Bin County,Harbin City.Through phenotypic observations and 16S rDNA identification,a bacterial strain identified as Pseudomonas hunanensis MGJ-2 was isolated,capable of utilizing nicotine as a carbon and nitrogen source for growth.High-performance liquid chromatography(HPLC)-1 analysis revealed that within 25 h,strain MGJ-2 could degrade nicotine 500 mg·L^(-1) with an efficiency exceeding 99.9%.Strain MGJ-2 was applied to tobacco,and after 15 days of incubation and fermentation,it degraded 10.57%of nicotine in tobacco.Overall,the discovery of strain MGJ-2 enriched the resources of nicotine-degrading strains.Its remarkable biodegradation performance held immense potential for future biodegradation of nicotine in tobacco.
