Aeromonas spp.are commonly found in spoilage of chilled meat.Aeromonas salmonicida NCM 29 and A.salmonicida NCM 57 have been discovered the spoilage heterogeneity in degrading myofibrillar protein.In this study,the tw...Aeromonas spp.are commonly found in spoilage of chilled meat.Aeromonas salmonicida NCM 29 and A.salmonicida NCM 57 have been discovered the spoilage heterogeneity in degrading myofibrillar protein.In this study,the two strains were tested to uncover the discrepancy of meat spoilage in collagen-rich chilled meat and extracted collagen.The results revealed that chicken claws,riched in collagen,inoculated with NCM 29 showed higher values of total viable counts(TVC),total volatile basic nitrogen(TVB-N),pH,adhered cells,trichloroacetic acid(TCA)-soluble peptides,and protease activity compared to those inoculated with NCM 57.Furthermore,NCM 29 generated higher quantity of volatile organic compounds related to meat spoilage.The collagenase((hemagglutinin protease(Hap))secreted by NCM 29 has been identified as the key factor responsible for the observed discrepancies in spoilage,which gradually degraded collagen into peptides and hydroxyproline.The capacity of Hap to degrade type Ⅰ collagen in vitro indicated that it has apparent proteolytic activity,which could reduce the average particle size and alter secondary structure of collagen.Sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE)further confirmed the degradation of theβ-chain in collagen.These findings not only provide a theoretical basis for in-depth investigation of the meat spoilage mechanisms of Aeromonas spp.,but also encourage us to take measures to avoid the spoilage of related bacteria such as Aeromonas spp.during the preservation process.展开更多
Aeromonas veronii is considered an emerging food-borne pathogen associated with a significant threat to public health,distributed in various aquatic environments and products.Hanks-type serine/threonine kinases(STKs)p...Aeromonas veronii is considered an emerging food-borne pathogen associated with a significant threat to public health,distributed in various aquatic environments and products.Hanks-type serine/threonine kinases(STKs)play a critical role in the pathogenesis of pathogens.However,the function of A.veronii STKs is currently unclear.By constructing a markerless prk A in-frame deletion strain,Δprk A,we found that i)the colonies of theΔprk A strain were larger after 1 h of high temperature at 50℃compared with the wild-type strain TH0426 and the complementary strain C-prk A,and the number of viable bacteria of theΔprk A strain increased significantly;ii)theΔprk A strain significantly enhanced the adhesion ability to epithelioma papulosum cyprini(EPC)cells;iii)theΔprk A strain was significantly more virulent than the TH0426 strain,at both the cellular and animal levels;and iv)RNA-seq results showed a total of 984 differentially expressed genes(DEGs)between theΔprk A strain and the TH0426 strain,which were enriched in 70 Kyoto Encyclopedia of Genes and Genomes(KEGG)metabolic pathways,mainly involved in bacterial ribosomes,flagellar assembly,type Ⅱ secretion system(T2SS),and lipopolysaccharide metabolic pathways.Taken together,the findings of this study indicate that the Hanks-type STK Prk A negatively regulates several biological processes,such as the temperature tolerance and virulence of A.veronii.The results of this study provide an important reference for further elucidation of the pathogenesis of A.veronii.展开更多
The aim of this study was to evaluate the factors influencing the inactivation effect of intense pulsed light(IPL)on Aeromonas salmonicida grown on chicken meat and skin,and to further develop prediction models of ina...The aim of this study was to evaluate the factors influencing the inactivation effect of intense pulsed light(IPL)on Aeromonas salmonicida grown on chicken meat and skin,and to further develop prediction models of inactivation.In this work,chicken meat and skin inoculated with meat-borne A.salmonicida isolates were subjected to IPL treatments under different conditions.The results showed that IPL had obvious bactericidal effect in the chicken skin and thickness groups when the treatment voltage and time were 7 V combined with 5 s.In addition,the lethality curves of A.salmonicida were fitted under IPL conditions of 3.5-7.5 V.The comparison of statistical parameters revealed that the Weibull model could best fit the mortality curves and could accurately predict the mortality dynamic of A.salmonicida grown on chicken skin.And further a secondary model between the scale factor b and the treatment voltage in Weibull model was established using linear equations,which determined that the secondary model could accurately predict the inactivation of A.salmonicida.This study provides a theoretical basis for future prediction models of Aeromonas,and also provides new ideas for sterilization approaches of meat-borne Aeromonas.展开更多
To identify the cause of mass mortality of adult Macrobrachium rosenbergii in a farm in Gaoyou City,Jiangsu Province,China,a dominant strain named DKQ-1 was isolated from the hepatopancreas of dying M.rosenbergii and ...To identify the cause of mass mortality of adult Macrobrachium rosenbergii in a farm in Gaoyou City,Jiangsu Province,China,a dominant strain named DKQ-1 was isolated from the hepatopancreas of dying M.rosenbergii and identified as Aeromonas dhakensis by purification culture,biochemical characterization,and 16S rRNA and gyrB gene sequence analysis.The results of the challenge test revealed that the strain was highly pathogenic and the 50%lethal dose(LD_(50))in 72 h to M.rosenbergii was 1.54×10^(5)CFU/mL.The amplification results of virulence genes show that strain DKQ-1 carried 9 virulence genes,including ascV,aexT,aer,act,lip,ompAI,gcaT,acg,and exu,supporting the strong virulence of strain DKQ-1 to M.rosenbergii.Histopathological observation of the hepatopancreas,gills,and intestines indicated that DKQ-1 injection into M.rosenbergii could cause serious tissue damage,which further supported the strong virulence of this strain.In addition,a drug susceptibility test revealed that strain DKQ-1 was sensitive to 16 kinds of antibiotics,resistant to 9 kinds of antibiotics,and had intermediate resistance to spectinomycin and kanamycin.This study is the first report of A.dhakensis isolated from M.rosenbergii and provided a reference for the pathogen identification of bacterial diseases in M.rosenbergii,and for the prevention and treatment caused by A.dhakensis.展开更多
[Objectives]To explore the function of hcp gene in Aeromonas hydrophila.[Methods]A pair of specific primers was designed referring to the hcp gene sequence of A.hydrophila.The hcp gene was amplified by PCR,and perform...[Objectives]To explore the function of hcp gene in Aeromonas hydrophila.[Methods]A pair of specific primers was designed referring to the hcp gene sequence of A.hydrophila.The hcp gene was amplified by PCR,and performed bioinformatics analysis.[Results]The hcp gene had a total length of 1650 bp and encoded 549 amino acids.The theoretical molecular weight of the protein predicted was about 59476.44 kDa.After predicting the N-terminal signal peptide structure of the amino acid sequence,neither obvious signal peptide cleavage site nor signal peptide was found,and the protein had no transmembrane region.The amino acid sequence had a N-glycosylation site,4 protein kinase C phosphorylation sites,7 casein kinase II phosphorylation sites,9 N-myristoylation sites,4 isoprene binding sites,10 microbody C-terminal target signal sites,and an ATP/GTP binding site motif A(P-ring).The amino acid sequence of hcp gene of A.hydrophila was performed homology analysis with other Aeromonas strains,and it showed higher homology with A.veronii.In the secondary structure,theα-helix,β-sheet,random coil and extended strand accounted for 45.36%,6.01%,37.52%and 11.11%,respectively.The tertiary structure model consisted of 18α-helix and 22β-sheet.Analysis of protein-protein network interaction demonstrated that the proteins interacting with Hcp protein were AHA_3407,nrfA,nirB-1,nirB-2 and AHA_1112.[Conclusions]Through the bioinformatics prediction results,the basic information of hcp gene of A.hydrophila is preliminarily understood,and the possible function of this protein is predicted,in order to provide guidance for subsequent vaccine research.展开更多
The study was conducted to identify Aeromonas spp.and Vibrio spp.from fresh Pangasius fish(n=153)in Cambodia and test their antimicrobial susceptibility to antibiotics.The samples were collected from different wet mar...The study was conducted to identify Aeromonas spp.and Vibrio spp.from fresh Pangasius fish(n=153)in Cambodia and test their antimicrobial susceptibility to antibiotics.The samples were collected from different wet markets of Phnom Penh city and Kampong Thom,and Siem Reap provinces.The bacteria were isolated by using selective medium and their AMR(Antimicrobial Resistance)profile was tested by API 20E technique,respectively.Susceptibility profile was determined for seven antibiotics commonly used.The Vibrio spp.(34.64%,n=53)was found to be higher than Aeromonas spp.(24.83%,n=38).Four Vibrio and four Aeromonas species were identified where V.parahaemolyticus(57%,n=30)was the highest,followed by V.cholerae(38%,n=20),V.fluvialis(3.8%,n=2)and V.aglinolyticus(1.9%,n=1),whereas A.hydrophila(47%,n=18)was the highest,followed by A.hydrophila/caviae(45%,n=17),A.sobria(5%,n=2),A.caviae(2.6%,n=1).All the species presented high multi-resistance to the tested antibiotics.The antibiotic susceptibility profile to ampicillin(74%-100%),ciprofloxacin(7%-100%),sulfamethoxazole/trimethoprim(14%-100%),florfenicol(14%-100%),oxytetracycline(7%-100%),erythromycin(10%-100%)and colistin sulphate(33%-100%)was revealed resistance level in Aeromonas spp.whereas few species of Vibrio spp.resistant to ampicillin(43%-100%),ciprofloxacin(14%-100%),sulfamethoxazole/trimethoprim(14%-100%),florfenicol(14%-100%),oxytetracycline(20%-100%),erythromycin(29%-100%),colistin sulphate(33%-100%)were also identified.The results revealed these Aeromonas spp.and Vibrio spp.are potentially reservoirs of antibiotic resistance genes.MDR(Multidrug Resistance)was widespread among the samples isolated.That is a high-risk source of contamination since those pathogens and antimicrobials are often used.Our findings highlight that the aquatic environment and fresh Pangasius fish act as reservoirs of AMR Aeromonas spp.and Vibrio spp.which underline the need for a judicious use of antimicrobials and timely surveillance of AMR in aquaculture.Overall,the findings of our study indicated the presence of A.hydrophila,A.hydrophila/caviae,A.caviae,A.sobria,V.parahaemolyticus,V.cholerae,V.alginolyticus and V.fluvialis and high MDR.This result will allow us to identify the potential risk over circulating isolates in animal health and public health and the spread through the food chain offering supports for appropriate sanitary actions.展开更多
[Objective] This study was conducted to develop compound probiotics that can be used as the alternatives of chemical drugs and antibiotics in aquaculture. [Method] Different concentrations of EM （effective microorgan...[Objective] This study was conducted to develop compound probiotics that can be used as the alternatives of chemical drugs and antibiotics in aquaculture. [Method] Different concentrations of EM （effective microorganisms） and Bacillus amyloliquefaciens were mixed at a ratio of 1：1, and sprayed on fish feed. The growth of intestinal villi of the fishes that had been fed with the feed mixed with compound probiotics for three months was observed; meanwhile, the content of in- testinal Aeromonas hydrophila was detected by real-time quantitative PCR. ｜Result] The compound probiotics promoted the development of intestinal villi, and inhibited the growth of A. hydrophila, and the effects were also concentration dependent. However, the compound probiotics did not increase the thickness of the intestinal serous layer, muscular layer and submucosal layer. [Conclusion] The compound probiotics we prepared can be used and popularized in aquiculture as it can inhibit the growth of A. hydrophila.展开更多
In order to effectively control diseases caused by Aeromonas veronii,pathogenic bacteria were isolated and incubated from infected soft-shelled turtles with traditional bacterial isolation method. Four strains of path...In order to effectively control diseases caused by Aeromonas veronii,pathogenic bacteria were isolated and incubated from infected soft-shelled turtles with traditional bacterial isolation method. Four strains of pathogenic bacteria were isolated and identified with traditional biochemical identification method and modern molecular biological identification techniques. According to the results, four strains of pathogenic bacteria were identified as A. veronii biovar sobria. Drug sensitivity test and in vitro antimicrobial test against Bacillus amyloliquefaciens were performed with agar diffusion method. The results showed that B. amyloliquefaciens and several antibiotics such as ofloxacin and gentamicin exerted strong antimicrobial effects on four isolates. B. amyloliquefaciens could be used for the prevention and control of diseases caused by A. veronii in aquaculture.展开更多
[Objective] The aim of this study is to investigate the bacteriostatic and bactericidal efficacy of povidone iodine as one kind of disinfectants for aquaculture on Aeromonas.[Method] With the standard strain of Aeromo...[Objective] The aim of this study is to investigate the bacteriostatic and bactericidal efficacy of povidone iodine as one kind of disinfectants for aquaculture on Aeromonas.[Method] With the standard strain of Aeromonas ATCC7966 and the Aeromonas strains isolated from diseased fish or aquatic environment as the tested strains,the bacteriostatic and bactericidal efficacy of povidone iodine was studied by double broth dilution method.[Result] The povidone iodine could inhibit the growth of Aeromonas strains at lower concentration,and killed Aeromonas strains at higher concentration.The minimum bacteriostatic concentration（MIC） of povidone iodine on Aeromonas sp.T1,Aeromonas sp T2 and Aeromonas sp.T4 was 125.00 mg/L,and the minimum bactericidal concentration（MBC） was 4.00 g/L.Whereas,the minimum bacteriostatic concentration（MIC） of povidone iodine on ATCC7966,Aeromonas sp.T3,Aeromonas sp T5 and Aeromonas sp.T6 was 250.00 mg/L,and the minimum bactericidal concentration（MBC） was 8.00 g/L.[Conclusion] This study provides certain basis for reasonable application of povidone iodine.展开更多
[Objective] This study aimed to isolate and identify the pathogens of soft-shelled turtle fulminant infectious disease,to provide the basis for the prevention and control of aquatic animal diseases.[Method] Commercial...[Objective] This study aimed to isolate and identify the pathogens of soft-shelled turtle fulminant infectious disease,to provide the basis for the prevention and control of aquatic animal diseases.[Method] Commercially available sick soft-shelled turtles were used as experimental materials,to isolate and identify the causative pathogens;pathogenicity test and toxin determination of the isolates were carried out;in addition,hyperimmune serum was prepared and its therapeutic effect was detected.[Result] Nine bacteria were isolated from the livers of sick soft-shelled turtles,including seven Aeromonas sobria strains（JA-1） and two A.caviae strains（JA-2）.The median lethal dose（LD50） of JA-1 and JA-2 was 4.3×10^5/ml and 5.5×10^7/ml,respectively;the broth culture supernatant of the two bacteria contains a type of toxin with hemolytic activity,indicating that the soft-shelled turtle fulminant infectious disease is caused by A.sobria and A.caviae.Vaccine was prepared by using the two bacteria and rabbit immunization with immunopotentiator,showing a titer of 1：512 and a cure rate of 100%.[Conclusion] This study laid foundation for the prevention and control of aquatic animal diseases.展开更多
Specific immunoglobulin (IgY) from egg yolk against Aeromonas hydrophila was produced by immunization of White Leghorn hens with formalin-killed whole cells of A. hydrophila. ELISA test using A. hydrophila as the coat...Specific immunoglobulin (IgY) from egg yolk against Aeromonas hydrophila was produced by immunization of White Leghorn hens with formalin-killed whole cells of A. hydrophila. ELISA test using A. hydrophila as the coating antigen revealed that the specific antibody titer started to increase in the egg yolk at the 13th day post-immunization (P/N=2.18), reached the peak at the 56th day (P/N=13.82), and remained at high level until day 133 (P/N=7.03). The antibody was purified by saturated ammonium sulphate with a recovery rate of 63.5%. The specific IgY inhibited the growth of A. hydrophila at a concentration of 1.0 mg/ml during the 18 h incubation. Pre-treatment of polyploid gibel carps Carassius auratus Gibelio with specific IgY had a protection rate of 60% (6/10) against challenge with A. hydrophila, while none of the fishes in the control groups receiving sterile phosphate buffered saline (PBS) or non-specific IgY survived the challenge. Treatment of fishes with the specific IgY 4 h after the challenge also had lower mortality (70%, 7/10), a 30% reduction against the control PBS or non-specific IgY groups (10/10). These results indicate that specific IgY antibodies could be obtained easily from hens immunized with an inactivated A. hydrophila and could provide a novel alternative approach to control of diseases in fishes caused by this organism.展开更多
BACKGROUND Aeromonas species are uncommon pathogens in biliary sepsis and cause substantial mortality in patients with impaired hepatobiliary function. Asia has the highest incidence of infection from Aeromonas,wherea...BACKGROUND Aeromonas species are uncommon pathogens in biliary sepsis and cause substantial mortality in patients with impaired hepatobiliary function. Asia has the highest incidence of infection from Aeromonas,whereas cases in the west are rare.CASE SUMMARY We report the case of a 64-year-old woman with advanced pancreatic cancer and jaundice who manifested fever,abdominal pain,severe thrombocytopenia,anemia and kidney failure following the insertion of a percutaneous transhepatic biliary drainage. Blood culture results revealed the presence of Aeromonas veronii biovar veronii(A. veronii biovar veronii). After antibiotic therapy and transfusions,the life-threatening clinical conditions of the patient improved and she was discharged.CONCLUSION This was a rare case of infection,probably the first to be reported in West countries,caused by A. veronii biovar veronii following biliary drainage. A finding of Aeromonas must alert clinician to the possibility of severe sepsis.展开更多
Recently, the rarely reported tet(31) tetracycline resistance determinant was commonly found in Aeromonas salmonicida, Gallibacterium anatis, and Oblitimonas alkaliphila isolated from farming animals and related envir...Recently, the rarely reported tet(31) tetracycline resistance determinant was commonly found in Aeromonas salmonicida, Gallibacterium anatis, and Oblitimonas alkaliphila isolated from farming animals and related environment. However, its distribution in other bacteria and potential molecular dissemination mechanism in environment are still unknown. The purpose of this study was to investigate the potential mechanism underlying dissemination of tet(31) by analysing the tet(31)-carrying fragments in A. caviae strains isolated from an aerobic biofilm reactor treating oxytetracycline bearing wastewater. Twenty-three A. caviae strains were screened for the tet(31) gene by polymerase chain reaction(PCR). Three strains(two harbouring tet(31), one not) were subjected to whole genome sequencing using the PacBio RSII platform. Seventeen A. caviae strains carried the tet(31) gene and exhibited high resistance levels to oxytetracycline with minimum inhibitory concentrations(MICs)ranging from 256 to 512 mg/L. tet(31) was comprised of the transposon Tn6432 on the chromosome of A. caviae, and Tn6432 was also found in 15 additional tet(31)-positive A. caviae isolates by PCR. More important, Tn6432 was located on an integrative conjugative element(ICE)-like element, which could mediate the dissemination of the tet(31)-carrying transposon Tn6432 between bacteria. Comparative analysis demonstrated that Tn6432 homologs with the structure ISCR2-ΔphzF-tetR(31)-tet(31)-ΔglmM-sul2 were also carried by A. salmonicida, G. anatis, and O. alkaliphila, suggesting that this transposon can be transferred between species and even genera. This work provides the first report on the identification of the tet(31) gene in A. caviae, and will be helpful in exploring the dissemination mechanisms of tet(31) in water environment.展开更多
Objective This study aimed to evaluate the genetic diversity,virulence,and antimicrobial resistance of Aeromonas isolates from clinical patients,tap water systems,and food.Methods Ninety Aeromonas isolates were obtain...Objective This study aimed to evaluate the genetic diversity,virulence,and antimicrobial resistance of Aeromonas isolates from clinical patients,tap water systems,and food.Methods Ninety Aeromonas isolates were obtained from Ma’anshan,Anhui province,China,and subjected to multi-locus sequence typing(MLST)with six housekeeping genes.Their taxonomy was investigated using concatenated gyr B-cpn60 sequences,while their resistance to 12 antibiotics was evaluated.Ten putative virulence factors and several resistance genes were identified by PCR and sequencing.Results The 90 Aeromonas isolates were divided into 84 sequence types,80 of which were novel,indicating high genetic diversity.The Aeromonas isolates were classified into eight different species.PCR assays identified virulence genes in the isolates,with the enterotoxin and hemolysin genes act,aer A,alt,and ast found in 47(52.2%),13(14.4%),22(24.4%),and 12(13.3%)of the isolates,respectively.The majority of the isolates(≥90%)were susceptible to aztreonam,imipenem,cefepime,chloramphenicol,gentamicin,tetracycline,and ciprofloxacin.However,several resistance genes were detected in the isolates,as well as a new mcr-3 variant.Conclusions Sequence type,virulence properties,and antibiotic resistance vary in Aeromonas isolates from clinical patients,tap water systems,and food.展开更多
A strain WL-11 with high laccase activity was isolated from activated sludge collected from the effluent treatment plant of a textile and dyeing industry. It was identified as Aeromonas hydrophila by physiological tes...A strain WL-11 with high laccase activity was isolated from activated sludge collected from the effluent treatment plant of a textile and dyeing industry. It was identified as Aeromonas hydrophila by physiological test and 16S rDNA sequence analysis. A gene encoding of laccase from a newly isolated Aeromonas hydrophila WL-11 was cloned and characterized. Nucleotide sequence analysis showed an open reading frame of 1605 bp encoding a polypeptide comprised of 534 amino acids. The primary structure of the enzyme predicted the structural features characteristic of other laccases, including the conserved regions of four histidine-rich copper-binding sites. The predicted amino acid sequence showed a high homology （more than 60%） with bacterial laccases in the genome and protein databases and the highest degree of similarity （61% identity） was observed with the multicopper oxidase of KlebsieUa sp. 601. When expressed in Escherichia coli, the recombinant enzyme was overproduced in the cytoplasm as soluble and active form. The purified enzyme had an optimum pH of 2.6 and 8.0 for ABTS （2,2＇-azino-bis（3-ethylbenzthiazolinesulfonic acid） and DMP （2,6-dimethoxyphenol）, respectively. The kinetic study on ABTS revealed a higher affinity of this enzyme to this substrate than DMP.展开更多
Objective:To investigate a case of mass mortality of Garra rufa(G.rufa)from a fish hatchery farm in Slovakia.Methods:Causative bacterial agent was swabbing out of affected fish skin area and subsequently identified us...Objective:To investigate a case of mass mortality of Garra rufa(G.rufa)from a fish hatchery farm in Slovakia.Methods:Causative bacterial agent was swabbing out of affected fish skin area and subsequently identified using commercial test system.Antibiotic susceptibility was determined by the disk diffusion method.Results:Infected G.rufa was characterized by abnormal swimming behaviour,bleeding of skin lesions and local haemorrhages.Despite of using recommended aquatic antibiotic treatment no improvement was achieved and Aeromonas sobria{A.sobria)was identified as a causative agent of fish mortality.Due to massive fish mortality,antibiotic susceptibility of pure isolated culture of A.sobria was evaluated employing eight antibiotics against human infections.A.sobria was resistant only against one antibiotic,namely ampicilin.Conclusions:These results indicate that A.sobria can act as a primary pathogen of G.rufa and may be a potential risk factor for immunodeficient or immunoincompetent patients during the ichthyotherapy.展开更多
基金supported by projects funded by grants from the Natural Science Foundation of Jiangsu Province in China(BK20221515)the National Natural Science Foundation of China(32172266).
文摘Aeromonas spp.are commonly found in spoilage of chilled meat.Aeromonas salmonicida NCM 29 and A.salmonicida NCM 57 have been discovered the spoilage heterogeneity in degrading myofibrillar protein.In this study,the two strains were tested to uncover the discrepancy of meat spoilage in collagen-rich chilled meat and extracted collagen.The results revealed that chicken claws,riched in collagen,inoculated with NCM 29 showed higher values of total viable counts(TVC),total volatile basic nitrogen(TVB-N),pH,adhered cells,trichloroacetic acid(TCA)-soluble peptides,and protease activity compared to those inoculated with NCM 57.Furthermore,NCM 29 generated higher quantity of volatile organic compounds related to meat spoilage.The collagenase((hemagglutinin protease(Hap))secreted by NCM 29 has been identified as the key factor responsible for the observed discrepancies in spoilage,which gradually degraded collagen into peptides and hydroxyproline.The capacity of Hap to degrade type Ⅰ collagen in vitro indicated that it has apparent proteolytic activity,which could reduce the average particle size and alter secondary structure of collagen.Sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE)further confirmed the degradation of theβ-chain in collagen.These findings not only provide a theoretical basis for in-depth investigation of the meat spoilage mechanisms of Aeromonas spp.,but also encourage us to take measures to avoid the spoilage of related bacteria such as Aeromonas spp.during the preservation process.
基金The Shandong Natural Science Foundation Youth Fund Project(ZR2022QC079,ZR2023QD024)provided funding for this work。
文摘Aeromonas veronii is considered an emerging food-borne pathogen associated with a significant threat to public health,distributed in various aquatic environments and products.Hanks-type serine/threonine kinases(STKs)play a critical role in the pathogenesis of pathogens.However,the function of A.veronii STKs is currently unclear.By constructing a markerless prk A in-frame deletion strain,Δprk A,we found that i)the colonies of theΔprk A strain were larger after 1 h of high temperature at 50℃compared with the wild-type strain TH0426 and the complementary strain C-prk A,and the number of viable bacteria of theΔprk A strain increased significantly;ii)theΔprk A strain significantly enhanced the adhesion ability to epithelioma papulosum cyprini(EPC)cells;iii)theΔprk A strain was significantly more virulent than the TH0426 strain,at both the cellular and animal levels;and iv)RNA-seq results showed a total of 984 differentially expressed genes(DEGs)between theΔprk A strain and the TH0426 strain,which were enriched in 70 Kyoto Encyclopedia of Genes and Genomes(KEGG)metabolic pathways,mainly involved in bacterial ribosomes,flagellar assembly,type Ⅱ secretion system(T2SS),and lipopolysaccharide metabolic pathways.Taken together,the findings of this study indicate that the Hanks-type STK Prk A negatively regulates several biological processes,such as the temperature tolerance and virulence of A.veronii.The results of this study provide an important reference for further elucidation of the pathogenesis of A.veronii.
基金supported by projects funded by grants from the Natural Science Foundation of Jiangsu Province in China(BK20221515)the National Natural Science Foundation of China(32172266)the Changzhou Science and Technology Support Program(CE20222002)。
文摘The aim of this study was to evaluate the factors influencing the inactivation effect of intense pulsed light(IPL)on Aeromonas salmonicida grown on chicken meat and skin,and to further develop prediction models of inactivation.In this work,chicken meat and skin inoculated with meat-borne A.salmonicida isolates were subjected to IPL treatments under different conditions.The results showed that IPL had obvious bactericidal effect in the chicken skin and thickness groups when the treatment voltage and time were 7 V combined with 5 s.In addition,the lethality curves of A.salmonicida were fitted under IPL conditions of 3.5-7.5 V.The comparison of statistical parameters revealed that the Weibull model could best fit the mortality curves and could accurately predict the mortality dynamic of A.salmonicida grown on chicken skin.And further a secondary model between the scale factor b and the treatment voltage in Weibull model was established using linear equations,which determined that the secondary model could accurately predict the inactivation of A.salmonicida.This study provides a theoretical basis for future prediction models of Aeromonas,and also provides new ideas for sterilization approaches of meat-borne Aeromonas.
基金Supported by the Earmarked Fund for the China Agriculture Research System(No.CARS-48)the Key Scientific and Technological Grant of Zhejiang for Breeding New Agricultural Varieties(No.2021 C 02069-4-3)the Major Research&Development Program(modern agriculture)of Jiangsu Province(No.BE 2019352)。
文摘To identify the cause of mass mortality of adult Macrobrachium rosenbergii in a farm in Gaoyou City,Jiangsu Province,China,a dominant strain named DKQ-1 was isolated from the hepatopancreas of dying M.rosenbergii and identified as Aeromonas dhakensis by purification culture,biochemical characterization,and 16S rRNA and gyrB gene sequence analysis.The results of the challenge test revealed that the strain was highly pathogenic and the 50%lethal dose(LD_(50))in 72 h to M.rosenbergii was 1.54×10^(5)CFU/mL.The amplification results of virulence genes show that strain DKQ-1 carried 9 virulence genes,including ascV,aexT,aer,act,lip,ompAI,gcaT,acg,and exu,supporting the strong virulence of strain DKQ-1 to M.rosenbergii.Histopathological observation of the hepatopancreas,gills,and intestines indicated that DKQ-1 injection into M.rosenbergii could cause serious tissue damage,which further supported the strong virulence of this strain.In addition,a drug susceptibility test revealed that strain DKQ-1 was sensitive to 16 kinds of antibiotics,resistant to 9 kinds of antibiotics,and had intermediate resistance to spectinomycin and kanamycin.This study is the first report of A.dhakensis isolated from M.rosenbergii and provided a reference for the pathogen identification of bacterial diseases in M.rosenbergii,and for the prevention and treatment caused by A.dhakensis.
基金Supported by Outstanding Graduate Entering Laboratory Project of College of Fisheries,Guangdong Ocean UniversityNational Natural Science Foundation of China(32073015)+1 种基金Undergraduate Innovation and Entrepreneurship Training Program of Guangdong Ocean University(CXXL2023008)Undergraduate Innovation Team of Guangdong Ocean University(CCTD201802).
文摘[Objectives]To explore the function of hcp gene in Aeromonas hydrophila.[Methods]A pair of specific primers was designed referring to the hcp gene sequence of A.hydrophila.The hcp gene was amplified by PCR,and performed bioinformatics analysis.[Results]The hcp gene had a total length of 1650 bp and encoded 549 amino acids.The theoretical molecular weight of the protein predicted was about 59476.44 kDa.After predicting the N-terminal signal peptide structure of the amino acid sequence,neither obvious signal peptide cleavage site nor signal peptide was found,and the protein had no transmembrane region.The amino acid sequence had a N-glycosylation site,4 protein kinase C phosphorylation sites,7 casein kinase II phosphorylation sites,9 N-myristoylation sites,4 isoprene binding sites,10 microbody C-terminal target signal sites,and an ATP/GTP binding site motif A(P-ring).The amino acid sequence of hcp gene of A.hydrophila was performed homology analysis with other Aeromonas strains,and it showed higher homology with A.veronii.In the secondary structure,theα-helix,β-sheet,random coil and extended strand accounted for 45.36%,6.01%,37.52%and 11.11%,respectively.The tertiary structure model consisted of 18α-helix and 22β-sheet.Analysis of protein-protein network interaction demonstrated that the proteins interacting with Hcp protein were AHA_3407,nrfA,nirB-1,nirB-2 and AHA_1112.[Conclusions]Through the bioinformatics prediction results,the basic information of hcp gene of A.hydrophila is preliminarily understood,and the possible function of this protein is predicted,in order to provide guidance for subsequent vaccine research.
基金supported by grants from HEIP(Higher Education Improvement Project)Project and Royal University of Agriculture.
文摘The study was conducted to identify Aeromonas spp.and Vibrio spp.from fresh Pangasius fish(n=153)in Cambodia and test their antimicrobial susceptibility to antibiotics.The samples were collected from different wet markets of Phnom Penh city and Kampong Thom,and Siem Reap provinces.The bacteria were isolated by using selective medium and their AMR(Antimicrobial Resistance)profile was tested by API 20E technique,respectively.Susceptibility profile was determined for seven antibiotics commonly used.The Vibrio spp.(34.64%,n=53)was found to be higher than Aeromonas spp.(24.83%,n=38).Four Vibrio and four Aeromonas species were identified where V.parahaemolyticus(57%,n=30)was the highest,followed by V.cholerae(38%,n=20),V.fluvialis(3.8%,n=2)and V.aglinolyticus(1.9%,n=1),whereas A.hydrophila(47%,n=18)was the highest,followed by A.hydrophila/caviae(45%,n=17),A.sobria(5%,n=2),A.caviae(2.6%,n=1).All the species presented high multi-resistance to the tested antibiotics.The antibiotic susceptibility profile to ampicillin(74%-100%),ciprofloxacin(7%-100%),sulfamethoxazole/trimethoprim(14%-100%),florfenicol(14%-100%),oxytetracycline(7%-100%),erythromycin(10%-100%)and colistin sulphate(33%-100%)was revealed resistance level in Aeromonas spp.whereas few species of Vibrio spp.resistant to ampicillin(43%-100%),ciprofloxacin(14%-100%),sulfamethoxazole/trimethoprim(14%-100%),florfenicol(14%-100%),oxytetracycline(20%-100%),erythromycin(29%-100%),colistin sulphate(33%-100%)were also identified.The results revealed these Aeromonas spp.and Vibrio spp.are potentially reservoirs of antibiotic resistance genes.MDR(Multidrug Resistance)was widespread among the samples isolated.That is a high-risk source of contamination since those pathogens and antimicrobials are often used.Our findings highlight that the aquatic environment and fresh Pangasius fish act as reservoirs of AMR Aeromonas spp.and Vibrio spp.which underline the need for a judicious use of antimicrobials and timely surveillance of AMR in aquaculture.Overall,the findings of our study indicated the presence of A.hydrophila,A.hydrophila/caviae,A.caviae,A.sobria,V.parahaemolyticus,V.cholerae,V.alginolyticus and V.fluvialis and high MDR.This result will allow us to identify the potential risk over circulating isolates in animal health and public health and the spread through the food chain offering supports for appropriate sanitary actions.
基金Supported by the Corporation Project(09003699)Foundation of the Education Department of Jiangxi Province(GJJ150416)Foundation of the Science and Technology Department of Jiangxi Province(20122BBF60082)~~
文摘[Objective] This study was conducted to develop compound probiotics that can be used as the alternatives of chemical drugs and antibiotics in aquaculture. [Method] Different concentrations of EM （effective microorganisms） and Bacillus amyloliquefaciens were mixed at a ratio of 1：1, and sprayed on fish feed. The growth of intestinal villi of the fishes that had been fed with the feed mixed with compound probiotics for three months was observed; meanwhile, the content of in- testinal Aeromonas hydrophila was detected by real-time quantitative PCR. ｜Result] The compound probiotics promoted the development of intestinal villi, and inhibited the growth of A. hydrophila, and the effects were also concentration dependent. However, the compound probiotics did not increase the thickness of the intestinal serous layer, muscular layer and submucosal layer. [Conclusion] The compound probiotics we prepared can be used and popularized in aquiculture as it can inhibit the growth of A. hydrophila.
基金Supported by Crosswise Project of Jiangxi Agricultural University(09003699)Project of Department of Education of Jiangxi Province(GJJ12237)Project of Jiangxi Provincial Department of Science and Technology(20122BBF60082)~~
文摘In order to effectively control diseases caused by Aeromonas veronii,pathogenic bacteria were isolated and incubated from infected soft-shelled turtles with traditional bacterial isolation method. Four strains of pathogenic bacteria were isolated and identified with traditional biochemical identification method and modern molecular biological identification techniques. According to the results, four strains of pathogenic bacteria were identified as A. veronii biovar sobria. Drug sensitivity test and in vitro antimicrobial test against Bacillus amyloliquefaciens were performed with agar diffusion method. The results showed that B. amyloliquefaciens and several antibiotics such as ofloxacin and gentamicin exerted strong antimicrobial effects on four isolates. B. amyloliquefaciens could be used for the prevention and control of diseases caused by A. veronii in aquaculture.
基金Supported by Startup Program for Doctors of Yangtze University(801200010110)~~
文摘[Objective] The aim of this study is to investigate the bacteriostatic and bactericidal efficacy of povidone iodine as one kind of disinfectants for aquaculture on Aeromonas.[Method] With the standard strain of Aeromonas ATCC7966 and the Aeromonas strains isolated from diseased fish or aquatic environment as the tested strains,the bacteriostatic and bactericidal efficacy of povidone iodine was studied by double broth dilution method.[Result] The povidone iodine could inhibit the growth of Aeromonas strains at lower concentration,and killed Aeromonas strains at higher concentration.The minimum bacteriostatic concentration（MIC） of povidone iodine on Aeromonas sp.T1,Aeromonas sp T2 and Aeromonas sp.T4 was 125.00 mg/L,and the minimum bactericidal concentration（MBC） was 4.00 g/L.Whereas,the minimum bacteriostatic concentration（MIC） of povidone iodine on ATCC7966,Aeromonas sp.T3,Aeromonas sp T5 and Aeromonas sp.T6 was 250.00 mg/L,and the minimum bactericidal concentration（MBC） was 8.00 g/L.[Conclusion] This study provides certain basis for reasonable application of povidone iodine.
基金Supported by Project of Science and Technology Bureau of Hebei Province(09220402D)~~
文摘[Objective] This study aimed to isolate and identify the pathogens of soft-shelled turtle fulminant infectious disease,to provide the basis for the prevention and control of aquatic animal diseases.[Method] Commercially available sick soft-shelled turtles were used as experimental materials,to isolate and identify the causative pathogens;pathogenicity test and toxin determination of the isolates were carried out;in addition,hyperimmune serum was prepared and its therapeutic effect was detected.[Result] Nine bacteria were isolated from the livers of sick soft-shelled turtles,including seven Aeromonas sobria strains（JA-1） and two A.caviae strains（JA-2）.The median lethal dose（LD50） of JA-1 and JA-2 was 4.3×10^5/ml and 5.5×10^7/ml,respectively;the broth culture supernatant of the two bacteria contains a type of toxin with hemolytic activity,indicating that the soft-shelled turtle fulminant infectious disease is caused by A.sobria and A.caviae.Vaccine was prepared by using the two bacteria and rabbit immunization with immunopotentiator,showing a titer of 1：512 and a cure rate of 100%.[Conclusion] This study laid foundation for the prevention and control of aquatic animal diseases.
基金Project (No. 2004C26026) supported by the Science and Technology Department of Zhejiang Province, China
文摘Specific immunoglobulin (IgY) from egg yolk against Aeromonas hydrophila was produced by immunization of White Leghorn hens with formalin-killed whole cells of A. hydrophila. ELISA test using A. hydrophila as the coating antigen revealed that the specific antibody titer started to increase in the egg yolk at the 13th day post-immunization (P/N=2.18), reached the peak at the 56th day (P/N=13.82), and remained at high level until day 133 (P/N=7.03). The antibody was purified by saturated ammonium sulphate with a recovery rate of 63.5%. The specific IgY inhibited the growth of A. hydrophila at a concentration of 1.0 mg/ml during the 18 h incubation. Pre-treatment of polyploid gibel carps Carassius auratus Gibelio with specific IgY had a protection rate of 60% (6/10) against challenge with A. hydrophila, while none of the fishes in the control groups receiving sterile phosphate buffered saline (PBS) or non-specific IgY survived the challenge. Treatment of fishes with the specific IgY 4 h after the challenge also had lower mortality (70%, 7/10), a 30% reduction against the control PBS or non-specific IgY groups (10/10). These results indicate that specific IgY antibodies could be obtained easily from hens immunized with an inactivated A. hydrophila and could provide a novel alternative approach to control of diseases in fishes caused by this organism.
文摘BACKGROUND Aeromonas species are uncommon pathogens in biliary sepsis and cause substantial mortality in patients with impaired hepatobiliary function. Asia has the highest incidence of infection from Aeromonas,whereas cases in the west are rare.CASE SUMMARY We report the case of a 64-year-old woman with advanced pancreatic cancer and jaundice who manifested fever,abdominal pain,severe thrombocytopenia,anemia and kidney failure following the insertion of a percutaneous transhepatic biliary drainage. Blood culture results revealed the presence of Aeromonas veronii biovar veronii(A. veronii biovar veronii). After antibiotic therapy and transfusions,the life-threatening clinical conditions of the patient improved and she was discharged.CONCLUSION This was a rare case of infection,probably the first to be reported in West countries,caused by A. veronii biovar veronii following biliary drainage. A finding of Aeromonas must alert clinician to the possibility of severe sepsis.
基金supported by the National Natural Scientific Foundation of China (No.21437005)
文摘Recently, the rarely reported tet(31) tetracycline resistance determinant was commonly found in Aeromonas salmonicida, Gallibacterium anatis, and Oblitimonas alkaliphila isolated from farming animals and related environment. However, its distribution in other bacteria and potential molecular dissemination mechanism in environment are still unknown. The purpose of this study was to investigate the potential mechanism underlying dissemination of tet(31) by analysing the tet(31)-carrying fragments in A. caviae strains isolated from an aerobic biofilm reactor treating oxytetracycline bearing wastewater. Twenty-three A. caviae strains were screened for the tet(31) gene by polymerase chain reaction(PCR). Three strains(two harbouring tet(31), one not) were subjected to whole genome sequencing using the PacBio RSII platform. Seventeen A. caviae strains carried the tet(31) gene and exhibited high resistance levels to oxytetracycline with minimum inhibitory concentrations(MICs)ranging from 256 to 512 mg/L. tet(31) was comprised of the transposon Tn6432 on the chromosome of A. caviae, and Tn6432 was also found in 15 additional tet(31)-positive A. caviae isolates by PCR. More important, Tn6432 was located on an integrative conjugative element(ICE)-like element, which could mediate the dissemination of the tet(31)-carrying transposon Tn6432 between bacteria. Comparative analysis demonstrated that Tn6432 homologs with the structure ISCR2-ΔphzF-tetR(31)-tet(31)-ΔglmM-sul2 were also carried by A. salmonicida, G. anatis, and O. alkaliphila, suggesting that this transposon can be transferred between species and even genera. This work provides the first report on the identification of the tet(31) gene in A. caviae, and will be helpful in exploring the dissemination mechanisms of tet(31) in water environment.
基金supported by the National Natural Science Foundation of China grant numbers NSFC 81861138053 and NSFC 31761133004。
文摘Objective This study aimed to evaluate the genetic diversity,virulence,and antimicrobial resistance of Aeromonas isolates from clinical patients,tap water systems,and food.Methods Ninety Aeromonas isolates were obtained from Ma’anshan,Anhui province,China,and subjected to multi-locus sequence typing(MLST)with six housekeeping genes.Their taxonomy was investigated using concatenated gyr B-cpn60 sequences,while their resistance to 12 antibiotics was evaluated.Ten putative virulence factors and several resistance genes were identified by PCR and sequencing.Results The 90 Aeromonas isolates were divided into 84 sequence types,80 of which were novel,indicating high genetic diversity.The Aeromonas isolates were classified into eight different species.PCR assays identified virulence genes in the isolates,with the enterotoxin and hemolysin genes act,aer A,alt,and ast found in 47(52.2%),13(14.4%),22(24.4%),and 12(13.3%)of the isolates,respectively.The majority of the isolates(≥90%)were susceptible to aztreonam,imipenem,cefepime,chloramphenicol,gentamicin,tetracycline,and ciprofloxacin.However,several resistance genes were detected in the isolates,as well as a new mcr-3 variant.Conclusions Sequence type,virulence properties,and antibiotic resistance vary in Aeromonas isolates from clinical patients,tap water systems,and food.
基金supported by the Korea Research Foundation Grant funded by the Korean Government(MOEHRD,Basic Research Promotion Fund) (No.KRF-2007-313-D00402)
文摘A strain WL-11 with high laccase activity was isolated from activated sludge collected from the effluent treatment plant of a textile and dyeing industry. It was identified as Aeromonas hydrophila by physiological test and 16S rDNA sequence analysis. A gene encoding of laccase from a newly isolated Aeromonas hydrophila WL-11 was cloned and characterized. Nucleotide sequence analysis showed an open reading frame of 1605 bp encoding a polypeptide comprised of 534 amino acids. The primary structure of the enzyme predicted the structural features characteristic of other laccases, including the conserved regions of four histidine-rich copper-binding sites. The predicted amino acid sequence showed a high homology （more than 60%） with bacterial laccases in the genome and protein databases and the highest degree of similarity （61% identity） was observed with the multicopper oxidase of KlebsieUa sp. 601. When expressed in Escherichia coli, the recombinant enzyme was overproduced in the cytoplasm as soluble and active form. The purified enzyme had an optimum pH of 2.6 and 8.0 for ABTS （2,2＇-azino-bis（3-ethylbenzthiazolinesulfonic acid） and DMP （2,6-dimethoxyphenol）, respectively. The kinetic study on ABTS revealed a higher affinity of this enzyme to this substrate than DMP.
基金supported by the Operational Program Research and Development and European Fund for Regional Development(EFRD)(grant No.ITMS 26240220020)
文摘Objective:To investigate a case of mass mortality of Garra rufa(G.rufa)from a fish hatchery farm in Slovakia.Methods:Causative bacterial agent was swabbing out of affected fish skin area and subsequently identified using commercial test system.Antibiotic susceptibility was determined by the disk diffusion method.Results:Infected G.rufa was characterized by abnormal swimming behaviour,bleeding of skin lesions and local haemorrhages.Despite of using recommended aquatic antibiotic treatment no improvement was achieved and Aeromonas sobria{A.sobria)was identified as a causative agent of fish mortality.Due to massive fish mortality,antibiotic susceptibility of pure isolated culture of A.sobria was evaluated employing eight antibiotics against human infections.A.sobria was resistant only against one antibiotic,namely ampicilin.Conclusions:These results indicate that A.sobria can act as a primary pathogen of G.rufa and may be a potential risk factor for immunodeficient or immunoincompetent patients during the ichthyotherapy.
