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
Pseudomonas fluorescens is a widespread spoilage bacterium in food,and its spoilage characteristics and biofilm formation are regulated by N-acyl-homoserine lactone(AHLs)quorum sensing(QS)system.Quorum quenching(QQ)is...Pseudomonas fluorescens is a widespread spoilage bacterium in food,and its spoilage characteristics and biofilm formation are regulated by N-acyl-homoserine lactone(AHLs)quorum sensing(QS)system.Quorum quenching(QQ)is considered as an effective strategy to control the spoilage bacteria.Therefore,this study revealed a new QQ bacteria Lactiplantibacillus plantarumYP4-1-2.Notably,the crude cell extract(CCE)from L.plantarum YP4-1-2 showed strongly QQ activity against the AHLs of P.fluorescens.The degradation rate of AHLs(N-octanoyl-L-homoserine lactone)reached 25.90%,78.57%and 100%at theCCE protein concentrations of 57,86 and 114 g/mL,respectively.In addition,the CCE could drastically reduce the formation of biofilm,bacterial motility(swimming and swarming),and the release of extracellular protease and biogenic amines of P.fluorescens.Real-time polymerase chain reaction(PCR)results revealed that the CCE downregulated QS-related genes(rhlI,rhlR,aprX,algA,orm,flgA,and ldcA).Finally,using whole-genome sequencing analysis,the active substance in the CCE was identified to be penicillin V acylase(PVA)and named LpPVA.Meanwhile,homologous modeling and molecular docking analysis showed that the binding effect of LpPVA on long-chain AHLs was better than that on short-chain AHLs.This study demonstrated that L.plantarum YP4-1-2 could be considered as a promising QS inhibitor and antibiofilm agent against foodborne spoilage bacteria.展开更多
AIM:To characterize oxidase-and urease-producing bacterial isolates,grown aerobically,that originated from antral biopsies of patients suffering from acid peptic diseases.METHODS:A total of 258 antral biopsy specimens...AIM:To characterize oxidase-and urease-producing bacterial isolates,grown aerobically,that originated from antral biopsies of patients suffering from acid peptic diseases.METHODS:A total of 258 antral biopsy specimens were subjected to isolation of bacteria followed by tests for oxidase and urease production,acid tolerance and aerobic growth.The selected isolates were further characterized by molecular techniques viz.amplifications for 16S rRNA using universal eubacterial and HSP60 gene specific primers.The amplicons were subjected to restriction analysis and partial sequencing.A phylogenetic tree was generated using unweighted pair group method with arithmetic mean(UPGMA) from evolutionary distance computed with bootstrap test of phylogeny.Assessment of acidity tolerance of bacteria isolated from antrum was performed using hydrochloric acid from 10-7 mol/L to 10-1 mol/L.RESULTS:Of the 258 antral biopsy specimens collected from patients,179(69.4%) were positive for urease production by rapid urease test and 31%(80/258) yielded typical Helicobacter pylori(H.pylori) after 5-7 d of incubation under a microaerophilic environment.A total of 240(93%) antral biopsies yielded homogeneous semi-translucent and small colonies after overnight incubation.The partial 16S rRNA sequences revealed that the isolates had 99% similarity with Pseudomonas species.A phylogenetic tree on the basis of 16S rRNA sequences denoted that JQ927226 and JQ927227 were likely to be related to Pseudomonas fluorescens(P.fluorescens).On the basis ofHSP60 sequences applied to the UPGMA phylogenetic tree,it was observed that isolated strains in an aerobic environment were likely to be P.fluorescens,and HSP60 sequences had more discriminatory potential rather than 16S rRNA sequences.Interestingly,this bacterium was acid tolerant for hours at low pH.Further,a total of 250(96.9%) genomic DNA samples of 258 biopsy specimens and DNA from 240 bacterial isolates were positive for the 613 bp amplicons by targeting P.fluorescens-specific conserved putative outer membrane protein gene sequences.CONCLUSION:This study indicates that bacterial isolates from antral biopsies grown aerobically were P.fluorescens,and thus acid-tolerant bacteria other than H.pylori can also colonize the stomach and may be implicated in pathogenesis/protection.展开更多
Drought is one of the major abiotic stresses which adversely affect crop plants limiting growth and yield potential.Structural and functional characterization of drought stress-induced genes has contributed to a bette...Drought is one of the major abiotic stresses which adversely affect crop plants limiting growth and yield potential.Structural and functional characterization of drought stress-induced genes has contributed to a better understanding of how plants respond and adapt to the drought stress.In the present study,differential display technique was employed to study the gene expression of rice plants at the reproductive stage that were subjected to drought stress by withholding water,Pseudomonas fluorescens strain(Pf1) treated plants subjected for drought stress by withholding water and control(well-watered).Differentially expressed c DNAs of six genes(COX1,PKDP,b ZIP1,AP2-EREBP,Hsp20 and COC1) were identified,cloned and sequenced.Real-time q PCR analysis showed that all the six genes were upregulated in drought-stressed plants treated with Pf1.This revealed that the remarkable influence of Pf1 colonization leads to drought tolerance at the reproductive stage.These results showed that high levels of gene expression in plants lacking adequate water can be remarkably influenced by Pf1 colonization,which might be a key element for induced systemic tolerance by microbes.展开更多
The biosorption characteristics of Cs（I） ions from aqueous solution using exopolymers （PFC02） produced from Pseudomonas fluorescens C-2 were investigated as a function of pH, biosorbent dosage, contact time and in...The biosorption characteristics of Cs（I） ions from aqueous solution using exopolymers （PFC02） produced from Pseudomonas fluorescens C-2 were investigated as a function of pH, biosorbent dosage, contact time and initial concentration. pH played a major role in the adsorption process, and the optimum pH for the removal of Cs（I） was 8.0. Langmuir, Freundlich and Dubinin-Radushkevich （D-R） models were applied to describe the biosorption isotherm of the Cs（I） ions by PFC02. The Lagergren first-order, pseudo second-order kinetic and intraparticle diffusion models were used to test the kinetic data. Langmuir model and D-R model fitted the equilibrium data better than the Freundlich isotherm. The monolayer adsorption capacities of PFC02 as obtained from Langmuir isotherm at 25°C was found to be 32.63 mg/g. From the D-R isotherm model, the mean free energy was calculated as 26.73 kJ/mol, indicating that the biosorption of cesium was chemisorption. The biosorption process was rapid, and the kinetic rates were best fitted to the pseudo second-order model, which indicated the biosorption process operated through chemisorption mechanism. FT-IR analysis of PFC02 showed the possible functional groups responsible for cesium adsorption were hydroxyl, carboxyl, carbonyl and sulphonate groups. SEM analysis showed the porous structure of the material while EDX analysis confirmed the adsorption of Cs（I） on PFC02. Cesium adsorbed onto the PFC02 could be desorbed efficiently using 1 mol/L HNO 3 , and the enrichment factor was 50.0. Furthermore, PFC02 could be reused five times with only about 8.25% regeneration loss. The developed method was successfully utilized for the removal of Cs（I） ions from aqueous solution.展开更多
Pseudomonas species have been widely studied as biological agents (BCAs) and it is alternative to the application of chemical fungicides. Our objective was to optimize nutritional and environmental conditions of the i...Pseudomonas species have been widely studied as biological agents (BCAs) and it is alternative to the application of chemical fungicides. Our objective was to optimize nutritional and environmental conditions of the isolated Pseudomonas fluorescens fp-5 for biomass and metabolites production and to evaluate itsagainst the grey mould disease caused by Botrytis cinerea on strawberry plants under field conditions. Pseudomonas fluorescens, showed antagonistic properties, in vitro, against thepathogen Botrytiscinerea. Effect of the separated secondary metabolites on the fungal growth by broth dilution technique and antifungal activity by agar well diffusion technique was studied. Response surface methodology was used to investigate the effects of four fermentation parameters (pH, incubation time, carbon and nitrogen concentrations) on biomass and bioactivemetabolites [antibiotic phenazin and siderophore] production. Glycerol was found to be the best carbon source for improved biomass and metabolites production. Meanwhile, peptone and yeast extract were found to be the best nitrogen source. Analysis of each formulation revealed that glycerol oil at 0.01% the best oil used for protect P. fluorescens for 3 months Under natural condition, P. fluorescens formulation was effective in reducing B. cinerea disease in strawberry leaves and fruits. Pre-harvest treatment protected fruits from Botrytis post-harvest disease in comparing of fungicide. In addition, the obtained results showed that bacterial treatment significantly increased thegrowth parameters as well as dry weights and yield.展开更多
INTRODUCTION P.fluorescens is an aerobic,Gram-negative bacillus related to Pseudomonas aeruginosa.Like other species of Pseudomonas,the organism is widespread in nature and is found in water,moist soil,and vegetation....INTRODUCTION P.fluorescens is an aerobic,Gram-negative bacillus related to Pseudomonas aeruginosa.Like other species of Pseudomonas,the organism is widespread in nature and is found in water,moist soil,and vegetation.Due to its low virulence,P.fluorescens is an infrequent cause of infections except for catheter-related bloodstream infections in cancer patients.From August 1,2003 to May 31,2016,Hyogo Emergency Medical Center and the Kobe Red Cross Hospital treated three cases of bloodstream infection展开更多
BACKGROUND The clinical incidence of spinal infection is gradually increasing,and its onset is insidious,easily leading to missed diagnosis and misdiagnosis,which may lead to serious complications such as nervous syst...BACKGROUND The clinical incidence of spinal infection is gradually increasing,and its onset is insidious,easily leading to missed diagnosis and misdiagnosis,which may lead to serious complications such as nervous system dysfunction,spinal instability and/or deformity,and cause a huge burden on society and families.Early identification of the causative agent and precision medicine will greatly reduce the suffering of patients.At present,the main pathogenic bacteria that cause spinal infection are Staphylococcus aureus,Streptococcus,Pneumococcus,Escherichia coli,and Klebsiella.There are no reports of spinal infection caused by Pseudomonas fluorescens.CASE SUMMARY We report a 32-year-old female patient with spinal infection.She presented with flank pain,initially thought to be bone metastases or bone tuberculosis,and had a family background of tumors.Her clinical features and changes in imaging and laboratory tests led to the suspicion of thoracic spine infection.Histopathology of the lesion showed inflammation,tissue culture of the lesion was negative several times,and the possible pathogen-Pseudomonas fluorescens was found after gene sequencing of the lesion.The patient recovered completely after a full course of antibiotic treatment.CONCLUSION This report increases the range of pathogens involved in spinal infections,highlights the unique advantages of gene sequencing technology in difficult-todiagnose diseases,and validates conservative treatment with a full course of antibiotics for spinal infections without complications.展开更多
Bacterial wilt complex disease of tomato(Solanum lycopersicum L.)was incited jointly by bacterial wilt pathogen Ralstonia solanacearum and Meloidogyne incognita worldwide.Bio-efficacy of bacterial antagonists i.e.B.am...Bacterial wilt complex disease of tomato(Solanum lycopersicum L.)was incited jointly by bacterial wilt pathogen Ralstonia solanacearum and Meloidogyne incognita worldwide.Bio-efficacy of bacterial antagonists i.e.B.amyloliquefaciens DSBA-11 and P.fluorescens DTPF-3 was studied against the wilt disease complex in tomato at National Phytotran facility Indian Agricultural Research Institute(IARI),New Delhi,at 26±2°C.Minimum wilt disease incidence(26.00%)with the highest bio-control efficacy(64.15%),less juvenile population(19.33 J2/g of soil)of M.incognita was recorded in the combined application of DTPF-3+DSBA-11 after 30 d of inoculation under glasshouse conditions.In a field study,minimum bacterial wilt disease incidences 19.0%and 20.4%were recorded in the bleaching powder treatment followed by mixed application of DSBA-11+DTPF-3,19.6%and 21.2%wilt incidence in 2014 and 2015 respectively.However,a reduction of root-knot gall index was recorded a maximum of 59.76%and 69.62%in DSBA-11+DTPF-3 treated plants followed by 54.88%and 60.13%over control in DTPF-3 treatment in 2014 and 2015 respectively.The yield of tomato fruit was increased over control by 17.48%and 16.97%in 2014 and 2015 respectively under field conditions.A combination of P.fluorescens DTPF-3+B.amyloliquefaciens DSBA-11 suppressed bacterial wilt and root-knot diseases and also increased the yield of the tomato fruit significantly(p<0.05)under field conditions.展开更多
The research question being studied in this paper is how do different types of bacteria as food (Pseudomonas fluorescens and Bacillus megaterium) affect the lifespan of Caenorhabditis elegans in dpy-11 mutant-type and...The research question being studied in this paper is how do different types of bacteria as food (Pseudomonas fluorescens and Bacillus megaterium) affect the lifespan of Caenorhabditis elegans in dpy-11 mutant-type and wild-type? P. fluorescens and B. megaterium will be the two pathogens that will be tested on two different types of C. elegans: mutant-type dpy-11 and wild-type. From the analysis of primary articles studying these pathogens, it can be concluded that P. fluorescens and B. megaterium are decent contenders for allowing C. elegans to grow and possibly extend the lifespan of it. P. fluorescens will allow the lifespan of the two types of nematodes to be longer. Additionally, the mu-tant-type dpy-11 of C. elegans will have a much longer lifespan, even double, compared to that of the wild-type. The results showed P. fluorescens had a longer lifespan than B. megaterium but not as long as C. elegans’ main food source, E. coli. C. elegans mutant dpy-11 had a longer lifespan than the wild-type. Furthermore, there were no C. elegans present in the B. megaterium wild-type plates.展开更多
The bio-control potential of rhizospere bacteria Pseudomonas fluorescens against plant-parasite nematode had been demonstrated. P. fluorescens had shown the effect to enhance tobacco resistance to root-knot nematode M...The bio-control potential of rhizospere bacteria Pseudomonas fluorescens against plant-parasite nematode had been demonstrated. P. fluorescens had shown the effect to enhance tobacco resistance to root-knot nematode Meloidogyne incognita. Inoculation with P. fluorescens in tobacco could lead to significant reductions in the number of juveniles that penetrated tobacco root and further life stage development of the juveniles. The number of juveniles penetrated into tobacco root in treatment with P. fluorescens is significantly different from CK at 2DAI,6DAI,8DAI and 10 DAI. Significant reduction and delayed development of juveniles that penetrated into tobacco root and treated were observed in treatment at14 DAI,21DAI,28 DAI and 35 DAI. In addition,P. fluorescens treatment leads to a significant reduction in the number of eggs per egg-mass at 35 DAI. The results show P. fluorescens induced a continuously suppression on root-knot nematode M. incognita throughout their entire early infection phase of root penetration,subsequent life stage development and reproduction.展开更多
Carbofuran insecticide is one of the insecticides most often used by Indonesian farmers.The United Nations Environment Program(UNEP)2011 in the decision of UNEP/FAO/RC/CRC.11/6,agreed that the active ingredient Carbof...Carbofuran insecticide is one of the insecticides most often used by Indonesian farmers.The United Nations Environment Program(UNEP)2011 in the decision of UNEP/FAO/RC/CRC.11/6,agreed that the active ingredient Carbofuran is dangerous to human health and the environment.P.fluorescens bacteria are known to be able to remediate carbofuran-contaminated soil.This study examines more deeply the biodegradation and biotransformation processes of Carbofuran in P.fluorescens bacteria.The research was carried out at the Laboratory of Plant Diseases,Faculty of Agriculture,Brawijaya University;Analytical Chemistry Laboratory,State Polytechnic of Malang;and Analytical Chemistry Laboratory,Udayana University from February to August 2020.The results showed that P.fluorescens was able to degrade the insecticide Carbofuran in liquid media up to 82%and the growth of P.fluorescens bacteria reached 2.9×10^(12) CFU/mL,bacteria P.fluorescens is able to degrade the insecticide Carbofuran in a mixture of soil and compost up to 85%and the growth of P.fluorescens bacteria reaches 7.5 x 1013 CFU/mL,resulting in Carbofuran insecticide derivatives from the biotransformation process,there are 3-hydroxy-7-phenol;2,3-dihydro-1-benzofuran-2,2,7-triol;(2Z)-2-[(2Z)-pent-2-en-1-ylidene]butane-1,4,4-trio;7-phenol;2,2,3-trihydroxy-2,3-dihydro-1-benzofuran-7-yl hydrogen carbonate;2,2-dimethyl-2,3-dihydro-1-benzofuran-7-yl acetate;7-(hydroxymethoxy)-2,3-dihydro-1-benzofuran-2,2,3,5-tetrol;3-hidroksi-2-fenilpropil Carbamat;2-(3-hydroperoxy-2-hydroxyphenyl)ethane-1,1-diol,3-keto-7-fenol;4-hydroxy-2,2-dimethyl-2,3-dihydro-1H-inden-1-one;3-hydroxy-carbofuran;and 7-methoxy-2,2-dimethyl-2,3-dihydro-1-benzofuran-3,5-diol.Carbofuran derivative compounds from the biodegradation of P.fluorescens bacteria are less toxic than the active ingredient Carbofuran.展开更多
LuxR solos sense exogenous signaling molecules and regulate microbial behaviors,thus facilitating intra-and inter-species communication among bacteria.However,studies on the role of LuxR solos in regulating the spoila...LuxR solos sense exogenous signaling molecules and regulate microbial behaviors,thus facilitating intra-and inter-species communication among bacteria.However,studies on the role of LuxR solos in regulating the spoilage potential of specific spoilage organisms are limited.In this study,we screened a LuxR solo EvgA,derived from Pseudomonas fluorescens PF08.qRT-PCR and molecular docking results indicated that EvgA responds and binds most strongly to exogenous N-3-tetradecanoyl-L-homoserine lactone(C14-HSL)through hydrogen bonds and hydrophobic interactions,with a-CDOCKER ENERGY of 45.87 kcal/mol.Subsequently,the evgA knockout(ΔevgA)and complementary evgA(ΔevgA-com)mutants of P.fluorescens PF08 were constructed through homologous recombination.ΔevgA mutants displayed diminished eavesdropping to exogenous C14-HSL(by 18.99±2.09%),reduced adhesion ability(by 30.33±0.36%),attenuated biofilm formation(by 15.97±0.14%),and decreased motility(swarming zones by 4.34±0.002 mm and swimming zones by 4.17±0.11 mm).In addition,EvgA deletion reduced spoilage factor production(hydrolysis zone),which included extracellular proteases,lipases,and biogenic amines(by 4.45±0.51 mm,10.12±0.10 mm,and 14.41±0.57 mm,respectively),thereby diminishing the spoilage of salmon fillets stored at 4℃.Notably,the addition of exogenous C14-HSL promoted the spoilage ability of all strains.This study emphasizes the important role of LuxR solo EvgA in AHLs-mediated quorum sensing and the spoilage potential of P.fluorescens PF08,which is expected to be a new target for controlling the spoilage of aquatic products.展开更多
As predominant culprits in food spoilage,Pseudomonas spp.,primarily Pseudomonas fluorescens,can form biofilms on food contact surfaces or in food-processing environments.This biofilm matrix can act as a protective bar...As predominant culprits in food spoilage,Pseudomonas spp.,primarily Pseudomonas fluorescens,can form biofilms on food contact surfaces or in food-processing environments.This biofilm matrix can act as a protective barrier for viable bacteria to prevent the penetration of antibacterial agents.This emphasizes the need to develop effective strategies to control Pseudomonas fluorescens biofilms.Natural products are considered the main source of eco-friendly antibiofilm agents.In this review,recent findings examining the effects of promising multi-targeted natural products against Pseudomonas fluorescens biofilms are summarized.Hopefully,this review can provide valuable insights into potential research targets and antibiofilm agents for further application in the food industry.展开更多
Pseudomonas fluorescens is one of the most important specific spoilage organism(SSO)causing the corruption of salmon.Therefore,it is very necessary to develop efficiently antibacterial materials against Pseudomonas fl...Pseudomonas fluorescens is one of the most important specific spoilage organism(SSO)causing the corruption of salmon.Therefore,it is very necessary to develop efficiently antibacterial materials against Pseudomonas fluorescens.Present work successfully synthesized a novel bio-MOF named surfactin@ZIF-8-NH_(2)(Sur@ZIF-8-NH_(2))through covalent chemical reactions used in salmon preservation.The bio-MOF showed regular morphology and well thermal stability.It also exhibited excellent antibacterial activity against Pseudomonas fluorescens at low concentration(MIC=0.0625 mg/mL,MBC=0.25 mg/mL).The good hydrophobicity of Sur@ZIF-8-NH_(2) made it easier to adsorb and insert to the membrane of cells.And the electrostatic interaction between the negative charge of Sur@ZIF-8-NH_(2) and the positive charge of the bacterial surface could disturb the charge balance of Pseudomonas fluorescens,damaging ion channels and rupturing the cell membrane,resulting in an increase in the conductivity of the solution.At this point,the Zn^(2+)(8.9 mg/L)released by Sur@ZIF-8-NH_(2) could more easily penetrate Pseudomonas fluorescens and cause the aggregation of reactive oxygen species(ROS),which further killed the cells.In addition,Sur@ZIF-8-NH_(2) could significantly inhibit the growth of Pseudomonas at the genus level and extend the shelf life of salmon by about 4 days.This investigation will be important for the development of the bio-MOFs used in aquatic products preservation.展开更多
Structured-illumination reflectance imaging(SIRI)provides a new means for food quality detection.This original work investigated the capability of(SIRI)technique coupled with multivariate chemometrics to evaluate the ...Structured-illumination reflectance imaging(SIRI)provides a new means for food quality detection.This original work investigated the capability of(SIRI)technique coupled with multivariate chemometrics to evaluate the microbial contamination in pork inoculated with Pseudomonas fluorescens and Brochothrix thermosphacta during storage at different temperatures.The prediction performances based on different spectrum and the textural features of direct component and amplitude component images demodulated from the SIRI pattern,as well as their data fusion were comprehensively compared.Based on the full wavelength spectrum(420-700 nm)of amplitude component images,the orthogonal signal correction coupled with support vector machine regression provided the best predictions of the number of P.fluorescens and B.thermosphacta in pork,with the determination coefficients of prediction(R_(p)^(2))values of 0.870 and 0.906,respectively.Besides,the prediction models based on the amplitude component or direct component image textural features and the data fusion models using spectrum and textural features from direct component and amplitude component images cannot significantly improve their prediction accuracy.Consequently,SIRI can be further considered as a potential technique for the rapid evaluation of microbial contaminations in pork meat.展开更多
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 the Open Foundation of Oceanology Research Institute of Bohai University(BDHYYJY2020002).
文摘Pseudomonas fluorescens is a widespread spoilage bacterium in food,and its spoilage characteristics and biofilm formation are regulated by N-acyl-homoserine lactone(AHLs)quorum sensing(QS)system.Quorum quenching(QQ)is considered as an effective strategy to control the spoilage bacteria.Therefore,this study revealed a new QQ bacteria Lactiplantibacillus plantarumYP4-1-2.Notably,the crude cell extract(CCE)from L.plantarum YP4-1-2 showed strongly QQ activity against the AHLs of P.fluorescens.The degradation rate of AHLs(N-octanoyl-L-homoserine lactone)reached 25.90%,78.57%and 100%at theCCE protein concentrations of 57,86 and 114 g/mL,respectively.In addition,the CCE could drastically reduce the formation of biofilm,bacterial motility(swimming and swarming),and the release of extracellular protease and biogenic amines of P.fluorescens.Real-time polymerase chain reaction(PCR)results revealed that the CCE downregulated QS-related genes(rhlI,rhlR,aprX,algA,orm,flgA,and ldcA).Finally,using whole-genome sequencing analysis,the active substance in the CCE was identified to be penicillin V acylase(PVA)and named LpPVA.Meanwhile,homologous modeling and molecular docking analysis showed that the binding effect of LpPVA on long-chain AHLs was better than that on short-chain AHLs.This study demonstrated that L.plantarum YP4-1-2 could be considered as a promising QS inhibitor and antibiofilm agent against foodborne spoilage bacteria.
基金Supported by Department of Biotechnology,Government of India,No. 102/IFD/SAN/PR1310/2006-07Council of Scientific and Industrial Research,New Delhi,India,in the form of Senior Research Fellowship (to Patel SK)
文摘AIM:To characterize oxidase-and urease-producing bacterial isolates,grown aerobically,that originated from antral biopsies of patients suffering from acid peptic diseases.METHODS:A total of 258 antral biopsy specimens were subjected to isolation of bacteria followed by tests for oxidase and urease production,acid tolerance and aerobic growth.The selected isolates were further characterized by molecular techniques viz.amplifications for 16S rRNA using universal eubacterial and HSP60 gene specific primers.The amplicons were subjected to restriction analysis and partial sequencing.A phylogenetic tree was generated using unweighted pair group method with arithmetic mean(UPGMA) from evolutionary distance computed with bootstrap test of phylogeny.Assessment of acidity tolerance of bacteria isolated from antrum was performed using hydrochloric acid from 10-7 mol/L to 10-1 mol/L.RESULTS:Of the 258 antral biopsy specimens collected from patients,179(69.4%) were positive for urease production by rapid urease test and 31%(80/258) yielded typical Helicobacter pylori(H.pylori) after 5-7 d of incubation under a microaerophilic environment.A total of 240(93%) antral biopsies yielded homogeneous semi-translucent and small colonies after overnight incubation.The partial 16S rRNA sequences revealed that the isolates had 99% similarity with Pseudomonas species.A phylogenetic tree on the basis of 16S rRNA sequences denoted that JQ927226 and JQ927227 were likely to be related to Pseudomonas fluorescens(P.fluorescens).On the basis ofHSP60 sequences applied to the UPGMA phylogenetic tree,it was observed that isolated strains in an aerobic environment were likely to be P.fluorescens,and HSP60 sequences had more discriminatory potential rather than 16S rRNA sequences.Interestingly,this bacterium was acid tolerant for hours at low pH.Further,a total of 250(96.9%) genomic DNA samples of 258 biopsy specimens and DNA from 240 bacterial isolates were positive for the 613 bp amplicons by targeting P.fluorescens-specific conserved putative outer membrane protein gene sequences.CONCLUSION:This study indicates that bacterial isolates from antral biopsies grown aerobically were P.fluorescens,and thus acid-tolerant bacteria other than H.pylori can also colonize the stomach and may be implicated in pathogenesis/protection.
基金the Jawaharlal Nehru University(JNU) research fellowship sponsored by the Department of Biotechnology(DBT),Government of India
文摘Drought is one of the major abiotic stresses which adversely affect crop plants limiting growth and yield potential.Structural and functional characterization of drought stress-induced genes has contributed to a better understanding of how plants respond and adapt to the drought stress.In the present study,differential display technique was employed to study the gene expression of rice plants at the reproductive stage that were subjected to drought stress by withholding water,Pseudomonas fluorescens strain(Pf1) treated plants subjected for drought stress by withholding water and control(well-watered).Differentially expressed c DNAs of six genes(COX1,PKDP,b ZIP1,AP2-EREBP,Hsp20 and COC1) were identified,cloned and sequenced.Real-time q PCR analysis showed that all the six genes were upregulated in drought-stressed plants treated with Pf1.This revealed that the remarkable influence of Pf1 colonization leads to drought tolerance at the reproductive stage.These results showed that high levels of gene expression in plants lacking adequate water can be remarkably influenced by Pf1 colonization,which might be a key element for induced systemic tolerance by microbes.
基金supported by the National Nat- ural Science Foundation of China (No. 30970309)the Natural Science Foundation of He'nan Province (No. 082102220009)the Natural Science Foundation of He'nan Province Education Department (No. 2009A610001)
文摘The biosorption characteristics of Cs（I） ions from aqueous solution using exopolymers （PFC02） produced from Pseudomonas fluorescens C-2 were investigated as a function of pH, biosorbent dosage, contact time and initial concentration. pH played a major role in the adsorption process, and the optimum pH for the removal of Cs（I） was 8.0. Langmuir, Freundlich and Dubinin-Radushkevich （D-R） models were applied to describe the biosorption isotherm of the Cs（I） ions by PFC02. The Lagergren first-order, pseudo second-order kinetic and intraparticle diffusion models were used to test the kinetic data. Langmuir model and D-R model fitted the equilibrium data better than the Freundlich isotherm. The monolayer adsorption capacities of PFC02 as obtained from Langmuir isotherm at 25°C was found to be 32.63 mg/g. From the D-R isotherm model, the mean free energy was calculated as 26.73 kJ/mol, indicating that the biosorption of cesium was chemisorption. The biosorption process was rapid, and the kinetic rates were best fitted to the pseudo second-order model, which indicated the biosorption process operated through chemisorption mechanism. FT-IR analysis of PFC02 showed the possible functional groups responsible for cesium adsorption were hydroxyl, carboxyl, carbonyl and sulphonate groups. SEM analysis showed the porous structure of the material while EDX analysis confirmed the adsorption of Cs（I） on PFC02. Cesium adsorbed onto the PFC02 could be desorbed efficiently using 1 mol/L HNO 3 , and the enrichment factor was 50.0. Furthermore, PFC02 could be reused five times with only about 8.25% regeneration loss. The developed method was successfully utilized for the removal of Cs（I） ions from aqueous solution.
文摘Pseudomonas species have been widely studied as biological agents (BCAs) and it is alternative to the application of chemical fungicides. Our objective was to optimize nutritional and environmental conditions of the isolated Pseudomonas fluorescens fp-5 for biomass and metabolites production and to evaluate itsagainst the grey mould disease caused by Botrytis cinerea on strawberry plants under field conditions. Pseudomonas fluorescens, showed antagonistic properties, in vitro, against thepathogen Botrytiscinerea. Effect of the separated secondary metabolites on the fungal growth by broth dilution technique and antifungal activity by agar well diffusion technique was studied. Response surface methodology was used to investigate the effects of four fermentation parameters (pH, incubation time, carbon and nitrogen concentrations) on biomass and bioactivemetabolites [antibiotic phenazin and siderophore] production. Glycerol was found to be the best carbon source for improved biomass and metabolites production. Meanwhile, peptone and yeast extract were found to be the best nitrogen source. Analysis of each formulation revealed that glycerol oil at 0.01% the best oil used for protect P. fluorescens for 3 months Under natural condition, P. fluorescens formulation was effective in reducing B. cinerea disease in strawberry leaves and fruits. Pre-harvest treatment protected fruits from Botrytis post-harvest disease in comparing of fungicide. In addition, the obtained results showed that bacterial treatment significantly increased thegrowth parameters as well as dry weights and yield.
文摘INTRODUCTION P.fluorescens is an aerobic,Gram-negative bacillus related to Pseudomonas aeruginosa.Like other species of Pseudomonas,the organism is widespread in nature and is found in water,moist soil,and vegetation.Due to its low virulence,P.fluorescens is an infrequent cause of infections except for catheter-related bloodstream infections in cancer patients.From August 1,2003 to May 31,2016,Hyogo Emergency Medical Center and the Kobe Red Cross Hospital treated three cases of bloodstream infection
文摘BACKGROUND The clinical incidence of spinal infection is gradually increasing,and its onset is insidious,easily leading to missed diagnosis and misdiagnosis,which may lead to serious complications such as nervous system dysfunction,spinal instability and/or deformity,and cause a huge burden on society and families.Early identification of the causative agent and precision medicine will greatly reduce the suffering of patients.At present,the main pathogenic bacteria that cause spinal infection are Staphylococcus aureus,Streptococcus,Pneumococcus,Escherichia coli,and Klebsiella.There are no reports of spinal infection caused by Pseudomonas fluorescens.CASE SUMMARY We report a 32-year-old female patient with spinal infection.She presented with flank pain,initially thought to be bone metastases or bone tuberculosis,and had a family background of tumors.Her clinical features and changes in imaging and laboratory tests led to the suspicion of thoracic spine infection.Histopathology of the lesion showed inflammation,tissue culture of the lesion was negative several times,and the possible pathogen-Pseudomonas fluorescens was found after gene sequencing of the lesion.The patient recovered completely after a full course of antibiotic treatment.CONCLUSION This report increases the range of pathogens involved in spinal infections,highlights the unique advantages of gene sequencing technology in difficult-todiagnose diseases,and validates conservative treatment with a full course of antibiotics for spinal infections without complications.
文摘Bacterial wilt complex disease of tomato(Solanum lycopersicum L.)was incited jointly by bacterial wilt pathogen Ralstonia solanacearum and Meloidogyne incognita worldwide.Bio-efficacy of bacterial antagonists i.e.B.amyloliquefaciens DSBA-11 and P.fluorescens DTPF-3 was studied against the wilt disease complex in tomato at National Phytotran facility Indian Agricultural Research Institute(IARI),New Delhi,at 26±2°C.Minimum wilt disease incidence(26.00%)with the highest bio-control efficacy(64.15%),less juvenile population(19.33 J2/g of soil)of M.incognita was recorded in the combined application of DTPF-3+DSBA-11 after 30 d of inoculation under glasshouse conditions.In a field study,minimum bacterial wilt disease incidences 19.0%and 20.4%were recorded in the bleaching powder treatment followed by mixed application of DSBA-11+DTPF-3,19.6%and 21.2%wilt incidence in 2014 and 2015 respectively.However,a reduction of root-knot gall index was recorded a maximum of 59.76%and 69.62%in DSBA-11+DTPF-3 treated plants followed by 54.88%and 60.13%over control in DTPF-3 treatment in 2014 and 2015 respectively.The yield of tomato fruit was increased over control by 17.48%and 16.97%in 2014 and 2015 respectively under field conditions.A combination of P.fluorescens DTPF-3+B.amyloliquefaciens DSBA-11 suppressed bacterial wilt and root-knot diseases and also increased the yield of the tomato fruit significantly(p<0.05)under field conditions.
文摘The research question being studied in this paper is how do different types of bacteria as food (Pseudomonas fluorescens and Bacillus megaterium) affect the lifespan of Caenorhabditis elegans in dpy-11 mutant-type and wild-type? P. fluorescens and B. megaterium will be the two pathogens that will be tested on two different types of C. elegans: mutant-type dpy-11 and wild-type. From the analysis of primary articles studying these pathogens, it can be concluded that P. fluorescens and B. megaterium are decent contenders for allowing C. elegans to grow and possibly extend the lifespan of it. P. fluorescens will allow the lifespan of the two types of nematodes to be longer. Additionally, the mu-tant-type dpy-11 of C. elegans will have a much longer lifespan, even double, compared to that of the wild-type. The results showed P. fluorescens had a longer lifespan than B. megaterium but not as long as C. elegans’ main food source, E. coli. C. elegans mutant dpy-11 had a longer lifespan than the wild-type. Furthermore, there were no C. elegans present in the B. megaterium wild-type plates.
文摘The bio-control potential of rhizospere bacteria Pseudomonas fluorescens against plant-parasite nematode had been demonstrated. P. fluorescens had shown the effect to enhance tobacco resistance to root-knot nematode Meloidogyne incognita. Inoculation with P. fluorescens in tobacco could lead to significant reductions in the number of juveniles that penetrated tobacco root and further life stage development of the juveniles. The number of juveniles penetrated into tobacco root in treatment with P. fluorescens is significantly different from CK at 2DAI,6DAI,8DAI and 10 DAI. Significant reduction and delayed development of juveniles that penetrated into tobacco root and treated were observed in treatment at14 DAI,21DAI,28 DAI and 35 DAI. In addition,P. fluorescens treatment leads to a significant reduction in the number of eggs per egg-mass at 35 DAI. The results show P. fluorescens induced a continuously suppression on root-knot nematode M. incognita throughout their entire early infection phase of root penetration,subsequent life stage development and reproduction.
文摘Carbofuran insecticide is one of the insecticides most often used by Indonesian farmers.The United Nations Environment Program(UNEP)2011 in the decision of UNEP/FAO/RC/CRC.11/6,agreed that the active ingredient Carbofuran is dangerous to human health and the environment.P.fluorescens bacteria are known to be able to remediate carbofuran-contaminated soil.This study examines more deeply the biodegradation and biotransformation processes of Carbofuran in P.fluorescens bacteria.The research was carried out at the Laboratory of Plant Diseases,Faculty of Agriculture,Brawijaya University;Analytical Chemistry Laboratory,State Polytechnic of Malang;and Analytical Chemistry Laboratory,Udayana University from February to August 2020.The results showed that P.fluorescens was able to degrade the insecticide Carbofuran in liquid media up to 82%and the growth of P.fluorescens bacteria reached 2.9×10^(12) CFU/mL,bacteria P.fluorescens is able to degrade the insecticide Carbofuran in a mixture of soil and compost up to 85%and the growth of P.fluorescens bacteria reaches 7.5 x 1013 CFU/mL,resulting in Carbofuran insecticide derivatives from the biotransformation process,there are 3-hydroxy-7-phenol;2,3-dihydro-1-benzofuran-2,2,7-triol;(2Z)-2-[(2Z)-pent-2-en-1-ylidene]butane-1,4,4-trio;7-phenol;2,2,3-trihydroxy-2,3-dihydro-1-benzofuran-7-yl hydrogen carbonate;2,2-dimethyl-2,3-dihydro-1-benzofuran-7-yl acetate;7-(hydroxymethoxy)-2,3-dihydro-1-benzofuran-2,2,3,5-tetrol;3-hidroksi-2-fenilpropil Carbamat;2-(3-hydroperoxy-2-hydroxyphenyl)ethane-1,1-diol,3-keto-7-fenol;4-hydroxy-2,2-dimethyl-2,3-dihydro-1H-inden-1-one;3-hydroxy-carbofuran;and 7-methoxy-2,2-dimethyl-2,3-dihydro-1-benzofuran-3,5-diol.Carbofuran derivative compounds from the biodegradation of P.fluorescens bacteria are less toxic than the active ingredient Carbofuran.
基金supported by the National Natural Science Foundation of China[Important Program,U20A2067]the Kunlun Mountain Scholar Project of Qinghai Province[2021-13]+4 种基金the Liaoning Marine Economic Development Project[2021-84]the Doctoral Startup Fund of Natural Science Foundation Program of Liaoning Province[2022-BS-301]Basic Research Project of Liaoning Provincial Department of Ed-ucation[LJ212410167063]the Open Fund of the Key Laboratory of Biotechnology and Bioresources Utilization(Dalian Minzu University),Ministry of Education[NO.KF2024002],Chinathe Open Fund of Institute of Ocean Research,Bohai University[BDHYYJY2023002,BDHYYJY2023003].
文摘LuxR solos sense exogenous signaling molecules and regulate microbial behaviors,thus facilitating intra-and inter-species communication among bacteria.However,studies on the role of LuxR solos in regulating the spoilage potential of specific spoilage organisms are limited.In this study,we screened a LuxR solo EvgA,derived from Pseudomonas fluorescens PF08.qRT-PCR and molecular docking results indicated that EvgA responds and binds most strongly to exogenous N-3-tetradecanoyl-L-homoserine lactone(C14-HSL)through hydrogen bonds and hydrophobic interactions,with a-CDOCKER ENERGY of 45.87 kcal/mol.Subsequently,the evgA knockout(ΔevgA)and complementary evgA(ΔevgA-com)mutants of P.fluorescens PF08 were constructed through homologous recombination.ΔevgA mutants displayed diminished eavesdropping to exogenous C14-HSL(by 18.99±2.09%),reduced adhesion ability(by 30.33±0.36%),attenuated biofilm formation(by 15.97±0.14%),and decreased motility(swarming zones by 4.34±0.002 mm and swimming zones by 4.17±0.11 mm).In addition,EvgA deletion reduced spoilage factor production(hydrolysis zone),which included extracellular proteases,lipases,and biogenic amines(by 4.45±0.51 mm,10.12±0.10 mm,and 14.41±0.57 mm,respectively),thereby diminishing the spoilage of salmon fillets stored at 4℃.Notably,the addition of exogenous C14-HSL promoted the spoilage ability of all strains.This study emphasizes the important role of LuxR solo EvgA in AHLs-mediated quorum sensing and the spoilage potential of P.fluorescens PF08,which is expected to be a new target for controlling the spoilage of aquatic products.
基金supported by the Open Fund of Institute of Ocean Research,Bohai University(BDHYYJY2023005)Doctoral Research Foundation of Bohai University(05013/0523bs019).
文摘As predominant culprits in food spoilage,Pseudomonas spp.,primarily Pseudomonas fluorescens,can form biofilms on food contact surfaces or in food-processing environments.This biofilm matrix can act as a protective barrier for viable bacteria to prevent the penetration of antibacterial agents.This emphasizes the need to develop effective strategies to control Pseudomonas fluorescens biofilms.Natural products are considered the main source of eco-friendly antibiofilm agents.In this review,recent findings examining the effects of promising multi-targeted natural products against Pseudomonas fluorescens biofilms are summarized.Hopefully,this review can provide valuable insights into potential research targets and antibiofilm agents for further application in the food industry.
基金supported by Ningbo Natural Science Foundation(2024J162)Scientific Research Fund of Zhejiang Provincial Education Department(Y202456807)+1 种基金Science Foundation of Donghai Laboratory(DH-2022KF0218)Zhoushan Science and Technology Plan Project(2019F12004,2021C41004).
文摘Pseudomonas fluorescens is one of the most important specific spoilage organism(SSO)causing the corruption of salmon.Therefore,it is very necessary to develop efficiently antibacterial materials against Pseudomonas fluorescens.Present work successfully synthesized a novel bio-MOF named surfactin@ZIF-8-NH_(2)(Sur@ZIF-8-NH_(2))through covalent chemical reactions used in salmon preservation.The bio-MOF showed regular morphology and well thermal stability.It also exhibited excellent antibacterial activity against Pseudomonas fluorescens at low concentration(MIC=0.0625 mg/mL,MBC=0.25 mg/mL).The good hydrophobicity of Sur@ZIF-8-NH_(2) made it easier to adsorb and insert to the membrane of cells.And the electrostatic interaction between the negative charge of Sur@ZIF-8-NH_(2) and the positive charge of the bacterial surface could disturb the charge balance of Pseudomonas fluorescens,damaging ion channels and rupturing the cell membrane,resulting in an increase in the conductivity of the solution.At this point,the Zn^(2+)(8.9 mg/L)released by Sur@ZIF-8-NH_(2) could more easily penetrate Pseudomonas fluorescens and cause the aggregation of reactive oxygen species(ROS),which further killed the cells.In addition,Sur@ZIF-8-NH_(2) could significantly inhibit the growth of Pseudomonas at the genus level and extend the shelf life of salmon by about 4 days.This investigation will be important for the development of the bio-MOFs used in aquatic products preservation.
基金supported by Key Research&Development Program of Jiangsu Province in China(BE2020693)Major Project of Science and Technology of Anhui Province(201903a06020010)+1 种基金Joint Key Project of Science and Technology Innovation of Yangtze River Delta in Anhui Province(202004g01020009)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
文摘Structured-illumination reflectance imaging(SIRI)provides a new means for food quality detection.This original work investigated the capability of(SIRI)technique coupled with multivariate chemometrics to evaluate the microbial contamination in pork inoculated with Pseudomonas fluorescens and Brochothrix thermosphacta during storage at different temperatures.The prediction performances based on different spectrum and the textural features of direct component and amplitude component images demodulated from the SIRI pattern,as well as their data fusion were comprehensively compared.Based on the full wavelength spectrum(420-700 nm)of amplitude component images,the orthogonal signal correction coupled with support vector machine regression provided the best predictions of the number of P.fluorescens and B.thermosphacta in pork,with the determination coefficients of prediction(R_(p)^(2))values of 0.870 and 0.906,respectively.Besides,the prediction models based on the amplitude component or direct component image textural features and the data fusion models using spectrum and textural features from direct component and amplitude component images cannot significantly improve their prediction accuracy.Consequently,SIRI can be further considered as a potential technique for the rapid evaluation of microbial contaminations in pork meat.
