基于核酸适配体的SYBR Green I qPCR法检测鳗弧菌(Vibrio anguillarum)

鳗弧菌(Vibrio anguillarum)可感染鲈鱼、鳗鲡等多种水产养殖动物,是水产养殖中的重要病原菌,对其进行快速检测是病害防控的基础。利用鳗弧菌与其核酸适配体间较强的亲和特异性,通过核酸适配体来识别、结合鳗弧菌,然后以结合的核酸适配体为模板,进行SYBR Green I实时荧光定量PCR(qPCR)扩增,通过Ct值来定量检测鳗弧菌的浓度,从而建立了鳗弧菌的适配体-qPCR定量检测方法。从特异性、标准曲线、灵敏度、重复性和应用效果对该方法进行分析,表明该方法具有很强的特异性,能特异性地扩增鳗弧菌,且对哈维氏弧菌、溶藻弧菌、变形假单胞菌、大肠杆菌、嗜水气单胞菌和迟钝爱德华氏菌均无扩增;在10^(3)~10^(11) CFU/L的检测范围内有较好的线性关系,可用于鳗弧菌的定量检测;同时,该方法有较高的灵敏度和稳定性,其最低检测限为10^(3) CFU/L,组内和组间变异系数分别小于0.17%和1.98%;最后采用该方法对鱼体组织样品进行了应用检测,证明了该方法具有较好的可行性和应用性,可用于水产品或食品中鳗弧菌的定量检测。

Transcriptome analysis reveals immune-related genes in tissues of Vibrio anguillarum-infected turbot Scophthalmus maximus

Turbot Scophthalmus maximus is an important mariculture fish species with high economic value.However,the bacterial diseases caused by Vibrio anguillarum infection bring huge economic losses to the turbot aquaculture industry.To understand the immune response of the turbot against V.anguillarum infection and to explore novel immune-related genes,the transcriptome analysis of turbot spleen and gills were conducted after V.anguillarum infection.Differentially expressed genes(DEGs)were identified in spleen and gill of the turbot amounted to 17261 and 16436,respectively.A large number of immunerelated DEGs were enriched in cytokine-cytokine receptor interaction signaling pathway,and the others by the kyoto encyclopedia of genes and genomes(KEGG)enrichment.The gene ontology(GO)classification analysis revealed that V.anguillarum infection had the greatest effect on biological processes and cellular components.Twelve immune-related DEGs were identified in the spleen(cstl.1,egfl6,lamb21,v2rx4,calcr,and gpr78a)and gills(ghra,sh3gl2a,cst12,inhbaa,cxcl8,and il-1b)by heat map.The proteinprotein interaction(PPI)networks were constructed to analyze the immune mechanism.The results demonstrate that the maturation and antigen processing of major histocompatibility complex(MHC)class II molecule,and calcitonin-or adrenomedullin-regulated physiological activity were important events in the immunity of turbot against V.anguillarum infection.In the gills,the protein interactions in TGF-βsignaling pathway,production of inflammatory factors,and endocytosis regulation were most significant.Our research laid a foundation for discovering novel immune-related genes and enriching the knowledge of immune mechanisms of turbot against V.anguillarum infection.

Molecular Cloning of clpX Gene from Vibrio alginolyticus HY9901 and Its Bioinformatics Analysis

According to the clpX gene sequence of Vibrio alginolyticus HY9901,a pair of specific primers were designed,and the full length was cloned by PCR and subjected to bioinformatics analysis.The results showed that the clpX gene was 1281 bp in length and encoded 426 amino acids.Its molecular structure formula was C 3842 H 6405 N 1281 O 1598 S 260,with a theoretical protein molecular weight of approximately 1044473.4 kDa and a theoretical pI value of 5.04.The clpX gene was predominantly situated within the cytoplasm,exhibiting unstable and hydrophilic protein characteristics.It possessed a signal peptide cleavage site,lacked a transmembrane region,and was not associated with any KEGG metabolic pathway.Additionally,it possessed 2 glycine phosphorylation sites,a CAMP-dependent protein kinase phosphorylation site,a C-terminal amidation modification site,6 protein kinase C phosphorylation sites,7 microbody C-terminal target signal sites,and an ATP/GTP site.The clpX phylogenetic tree was constructed using the MEGA 5.0 software via the neighbor-joining method.The results demonstrated that the clpX of V.alginolyticus exhibited up to 100%affinity with the clpX of Vibrio spp.The single subunit 3D structure model of the ClpX protein was obtained using the SWISS-MODEL program.A structural and functional analysis of the protein revealed the presence of three distinct ClpX structural and functional domains.In the prediction of secondary structure,the proportions ofα-helix,random coil,β-sheet and extended strand were 40.38%,37.09%,5.40%and 17.14%,respectively.The analysis of the ClpX protein through the STRING database revealed that the proteins interacting with the ClpX protein were Tig,Atpd,Hflb,Msrb-2,Rpod,Clpp,Clpa,Lon-1,Hfq,and ANP63951.1.A computational analysis of the ClpX protein identified a number of post-translational modification sites,including phosphorylation,acetylation,ubiquitination,glycosylation,methylation,S-palmitoylation,and lactylation.The significance of this study is to analyze the function of the clpX gene and establish a robust foundation for subsequent investigations into the mechanism of the clpX gene in Vibrio alginolyticus.

Gene Cloning and Bioinformatics Analysis of phoR Gene from Vibrio alginolyticus HY9901

PhoR is a histidine kinase in a two-component regulatory system that regulates phosphorus metabolic pathways and undertakes the key mission of information transmission in pathogenic bacteria.The full-length phoR gene was successfully cloned from the Vibrio alginolyticus HY9901 strain.A comprehensive analysis of the cloned gene was conducted using bioinformatics.Sequence analysis revealed that the total length of the phoR gene(GenBank accession No.:KJ958404.1)is 1299 bp,with the coding region containing a total of 432 amino acid residues.The phylogenetic tree of PhoR revealed that it belongs to the same subclade as V.diabolicus.The SMART program was employed for the purpose of functional domain prediction,which revealed that PhoR possesses three major functional domains:PAS(amino acids 98-166),HisKA(amino acids 205-272),and HATPase_c(amino acids 317-429).

Molecular Cloning and Bioinformatics Analysis of sucC Gene of Vibrio alginolyticus Strain HY9901

[Objectives]To clone the sucC gene of Vibrio alginolyticus strain HY9901 and conduct the bioinformatics analysis.[Methods]Based on the sucC gene of V.alginolyticus strain HY9901,specific primers were designed to amplify the full length sequence by PCR and make further analysis.[Results]The theoretical molecular weight of SucC protein was about 41528.45 Da,and the full length was 1167 bp,encoding 388 amino acids.It has no signal peptide and transmembrane region,and has a variety of functional sites.It is predicted that it is mainly located in the cytoplasm,and the ubiquitin and lactate modification sites overlap,and it has high gene homology with Vibrio parahaemolyticus.Theα-helix,random coil and extended strand are the main secondary structures.The similarity between the constructed three-level structure model and the template is high.[Conclusions]This study reveals the structural characteristics and functional potential of SucC protein,and provides a theoretical basis for the study of drug resistance mechanism and prevention strategies.

Molecular Cloning and Bioinformatics Analysis of msrA Gene from Vibrio alginolyticus Strain HY9901

[Objectives]This study was conducted to understand the structure and function of MsrA protein.[Methods]With Vibrio alginolyticus HY9901 as the object of study,primers were designed to amplify the full-length gene of msrA,and its bioinformatics analysis was carried out.[Results]The full length of msrA gene was 639 bp,encoding 212 amino acids,and its theoretical molecular weight was about 23729.60 Da.The protein had a stable structure,and it was hydrophobic overall.The structure of signal peptides at the N terminal of the amino acid sequence was predicted,and it was found that there was no signal peptide cleavage site and no transmembrane region.The amino acid sequence of MsrA contained multiple signal binding sites.Protein subcellular localization showed that MsrA protein was most likely located in the cytoplasm.Homology analysis showed that MsrA of V.alginolyticus had high homology with other Vibrio species,and the highest homology with V.alginolyticus.In the prediction of functional domains,MsrA had the function of methionine sulfoxide reduction.In secondary structure prediction,MsrA contained random coils at a proportion of 46.70%,which was the highest.The similarity between the tertiary structure model of MsrA and template Q87SW6.1.A was 89.15%.PTM analysis showed that MsrA protein had many PTM modification sites such as phosphorylation and glycosylation sites.[Conclusions]This study provides some reference value for further study on the role of MsrA in bacterial antioxidant stress.

Molecular Cloning of sodB Gene from Vibrio alginolyticus HY9901 and Its Bioinformatics Analysis

Vibrio alginolyticus is a zoonotic bacterium.A pair of specific primers was designed using the sodB gene sequence of Vibrio alginolyticus HY9901 in order to amplify the full length of the gene by PCR.The results indicated that the total length of the sodB gene was 585 bp and that it could encode 194 amino acids.The predicted amino acid sequence derivation indicated that the molecular weight of the protein was approximately 21.56 kDa,with an isoelectric point of 4.95.Upon prediction of the N-terminal signal peptide structure of the protein,no significant signal peptide cleavage site was observed,indicating that the protein lacked both a signal peptide and a transmembrane region.The amino acid sequence contained an N-glycosylation site,a casein kinase II phosphorylation site,a microsomal C-terminal target signal site,and a manganese and iron superoxide dismutase signal site.The probability of intracytoplasmic localization of the SodB protein was 56.5%,which was analyzed according to the subcellular localization of the protein.The amino acid sequence of the sodB gene of V.alginolyticus exhibited 98%-100%homology to other Vibrio species,clustering into the same subfamily with V.parahaem,indicating a relatively close relationship between them.In the prediction of protein structure,the proportions ofα-helix,random coil,β-sheet,and extended strand were 48.45%,30.41%,5.67%,and 15.46%,respectively.The similarity to template 1dt0.1.A reached 71.58%.A PTM site analysis revealed the presence of phosphorylation,glycosylation,ubiquitination,sumoylation,acetylation,and methylation modification sites,as well as the absence of lactylation modification sites.

Molecular Cloning and Bioinformatics Analysis of cyaA Gene of Vibrio alginolyticus Strain HY9901

[Objectives]This study was conducted to explore the biological functions of cyaA gene of Vibrio alginolyticus.[Methods]With DNA of V.alginolyticus HY 9901 as a template,primers were designed according to the sequence of cyaA gene,and the cyaA gene was amplified by PCR.Bioinformatics analysis was performed.[Results]The cyaA gene of V.alginolyticus HY9901 was 2529 bp in size,and encoded 842 amino acids.The molecular structure of CyaA protein was C_(4358)H_(6745)N_(1171)O_(1286)S_(35).Its theoretical molecular weight was 97.24167 kDa and the theoretical pI value was 5.56.It had no signal peptide and transmembrane domain.CyaA protein had three N-terminal glycosylation sites,one cAMP and cGMP-dependent protein kinase phosphorylation site,nine protein kinase C phosphorylation sites,nine casein kinase II phosphorylation sites,one tyrosine kinase phosphorylation site,seven N-terminal myristoylation sites,one pentenyl binding site and ten microbody C-terminal localization signal sites.Subcellular localization prediction showed that CyaA protein was mainly located in the nucleus and cytoplasm.Through multi-sequence alignment and phylogenetic tree construction,it was concluded that V.alginolyticus had high CyaA homology with other Vibrio species.cyaA of V.alginolyticus was clustered with Vibrio fluminensis and Vibrio marinisedimini,and they were closely related.The secondary structure of CyaA protein consisted ofα-helixes(43.11%),random coils(38.00%)and extended strands(14.49%).In protein network interaction,it was found that the proteins adjacent to CyaA protein were Crp-2,CpdA,Crr,PtsG-2,ANP67209.1,Crp-1,PykF,Pyk,RelA and Ndk.[Conclusions]This study provides a new idea for formulating strategies for the prevention and control of vibriosis.

基于核酸适配体的差减荧光法检测鳗弧菌(Vibrio anguillarum)

鳗弧菌(Vibrio anguillarum)可感染鳗鲡、虹鳟和大菱鲆等多种水产动物,是水产养殖中的一种重要病原菌,对其进行快速检测是病害防控的前提和基础。利用鳗弧菌与其核酸适配体之间有较强的亲和特异性,首次建立了一种基于核酸适配体的可定量检测鳗弧菌的差减荧光法。该方法对鳗弧菌有较好的特异性,对鳗弧菌的检测荧光值是其他菌(溶藻弧菌、哈维氏弧菌、铜绿假单胞菌、变形假单胞菌、嗜水气单胞菌、迟钝爱德华氏菌和大肠杆菌)的4~11倍,对鳗弧菌的最低检测限为102CFU/mL,可用于102~108CFU/mL的范围内的定量检测。通过对不同盐度海水和鱼体组织样品进行加标回收检测,结果表明,回收率和相对标准偏差等指标均符合相应的标准,说明该检测方法可用于海水样品和水产动物组织中鳗弧菌的检测。

Virulence changes in Vibrio parahaemolyticus during the freezing of Penaeus chinensis

Although Vibrio parahaemolyticus has become the most common pathogen in fresh and frozen seafood,its virulence changes have often been ignored during the processing of seafood.To investigate these potential risks,we used frozen Penaeus chinensis as examples,and the most virulent factors of V.parahaemolyticus,including amounts,viable but nonculturable(VBNC)status,toxins TDH and TRH,and virulence genes tdh and trh,were determined.Bacterial quantities were signifi cantly reduced during drain and sprinkling phases,but caused by different factors.By SYTO9 and PI staining showed that washing was the main reason for the bacterial reduction at the drain phase,while the strain entering VBNC state was another reason at sprinkling phase.Their hemolysis toxicity,produced by TDH and TRH,became stronger after inoculation on shrimp,and could be detected throughout the process.Moreover,tdh and trh also exhibited trends similar to that of the hemolysis toxicity test.tdh was almost to a two-fold expression level during ice-glazing phase,while trh only express at a low level,less than half of the expression level before inoculation.These results demonstrated that the strains were not dead during freezing process,but became VBNC cells,which still produced and accumulated toxins,especially TDH,the most virulent factor.

病原哈维氏弧菌(Vibrio harveyi)TS-628菌株基因组分析

哈维氏弧菌是海洋鱼类和无脊椎动物的重要条件致病菌,经常造成海水养殖动物严重病害,给水产养殖业造成巨大的经济损失,而不同来源的哈维氏弧菌的毒力存在很大差异。本研究采用第二代Illumina Hiseq平台与第三代PacBio平台相结合的测序技术,对分离自福建海域患病青石斑鱼的哈维氏弧菌TS-628菌株进行基因组测序和分析,挖掘该菌的基因组信息,从基因组层面了解该病原菌的毒力相关基因,以期为哈维氏弧菌后续致病机制的研究以及哈维氏弧菌病防治提供有力数据支撑。结果表明,哈维氏弧菌TS-628菌株基因组含2条染色体、2个质粒,其中1个质粒为新发现质粒;基因组大小为6151198 bp,基因组GC含量为44.68%,共编码5658个基因,共预测到毒力基因747个,毒力基因主要与细菌的黏附、摄铁系统及分泌系统有关;此外,还发现耐药基因294个,反映该菌株不仅具有编码多种毒力因子的潜力,同时具有抗多种药物的可能。

Resveratrol Prevents Vibrio vulnificus-Induced Sepsis by Attenuating Necroptosis

Objective This study investigated how the natural phytophenol and potent SIRT1 activator resveratrol(RSV)regulate necroptosis during Vibrio vulnificus(V.vulnificus)-induced sepsis and the potential mechanism.Methods The effect of RSV on V.vulnificus cytolysin(VVC)-induced necroptosis was analyzed in vitro using CCK-8 and Western blot assays.Enzyme-linked immunosorbent assays and quantitative real-time polymerase chain reaction,western blot,and immunohistochemistry and survival analyses were performed to elucidate the effect and mechanism of RSV on necroptosis in a V.vulnificus-induced sepsis mouse model.Results RSV relieved necroptosis induced by VVC in RAW264.7 and MLE12 cells.RSV also inhibited the inflammatory response,had a protective effect on histopathological changes,and reduced the expression level of the necroptosis indicator pMLKL in peritoneal macrophages,lung,spleen,and liver tissues of V.vulnificus-induced septic mice in vivo.Pretreatment with RSV downregulated the mRNA of the necroptosis indicator and protein expression in peritoneal macrophages and tissues of V.vulnificusinduced septic mice.RSV also improved the survival of V.vulnificus-induced septic mice.Conclusion Our findings collectively demonstrate that RSV prevented V.vulnificus-induced sepsis by attenuating necroptosis,highlighting its potency in the clinical management of V.vulnificus-induced sepsis.

Protein Containing the GGDEF Domain Affects Motility and Biofilm Formation in Vibrio cholerae and is Negatively Regulated by Fur and HapR

Objective This study aimed to investigate whether the VCA0560 gene acts as an active diguanylate cyclase(DGC)in Vibrio cholerae and how its transcription is regulated by Fur and Hap R.Methods The roles of VCA0560 was investigated by utilizing various phenotypic assays,including colony morphological characterization,crystal violet staining,Cyclic di-GMP(c-di-GMP)quantification,and swimming motility assay.The regulation of the VCA0560 gene by Fur and Hap R was analyzed by luminescence assay,electrophoretic mobility shift assay,and DNase I footprinting.Results VCA0560 gene mutation did not affect biofilm formation,motility,and c-di-GMP synthesis in V.cholerae,and its overexpression remarkably enhanced biofilm formation and intracellular c-di-GMP level but reduced motility capacity.The transcription of the VCA0560 gene was directly repressed by Fur and the master quorum sensing regulator Hap R.Conclusion Overexpressed VCA0560 functions as an active DGC in V.cholerae,and its transcription is repressed by Fur and Hap R.

Characterization of Caspase Gene Family Members in Spotted Sea Bass(Lateolabrax maculatus)and Their Expression Profiles in Response to Vibrio harveyi Infection

The caspase gene family is a crucial gene cluster that regulates apoptosis which contribute to programmed cell death,cell proliferation and differentiation,and several immune responses.In our study,a complete set of 12 caspase genes were identified in spotted sea bass Lateolabrax maculatus.These genes were divided into three subfamilies:2 inflammatory caspases(casp-1 and casp-14-like),5 apoptosis initiators(casp-2,casp-8a,casp-8b,casp-9,and casp-10),and 5 apoptosis executioners(casp-3a,casp-3b,casp-3-like,casp-6,and casp-7).Their phylogenetic relationships,synteny and gene structures were systematically analyzed.Furthermore,the relative expression profiles of the caspase family members in the liver,intestine,head kidney,and spleen were measured by q PCR after infection with Vibrio harveyi.The results showed that the overall mRNA levels of the caspase genes were dramatically increased after V.harveyi infection,and the expression patterns varied among genes and tissues.More caspase genes underwent pronounced expression changes in the head kidney and spleen than in the liver or intestine,mainly after 48 h of the challenge.Specifically,casp-3a,casp-3b,casp-3-like,casp-6,casp-7,casp-8a,casp-8b,casp-10,and casp-14-like in the head kidney,and casp-3-like,casp-6,casp-7,and casp-14-like in the spleen,were the most responsive caspase genes which may contribute significantly to immune regulation in spotted sea bass.Additionally,the apoptosis level in head kidney and spleen after infection were examined using the Caspase assay.Our study provides a systemic overview of the caspase gene family in spotted sea bass after V.harveyi infection and lays a foundation for further deciphering the biological roles of these caspase genes.

Immuno-Protective Efficiency of the Bivalent Inactivated Vaccine Against Vibrio scophthalmi and Aeromonas salmonicida Infections in Turbot(Scophthalmus maximus L.)

Vibrio scophthalmi and Aeromonas salmonicida can cause high turbot mortality and huge economic losses.Presently,vaccination is the most promising method for preventing communicable diseases.In this study,we used formalin to kill V.scophthalmi and A.salmonicida cells,and mixed with the mineralized oil adjuvant(Montanide^(TM)ISA 763 AVG)to prepare the bivalent inactivated vaccine.The results showed that turbot inoculated with the bivalent inactivated vaccine exhibited strong tolerance to the infection of V.scophthalmi and A.salmonicida,and no obvious clinical symptoms and pathological changes were observed.The activities of enzymes lysozyme,acid phosphatase and complement C3 had significantly increased after the vaccination.The antibody titer response of vaccinated turbot was greatly boosted,which was positively connected with the immunological impact according to ELISA results.Simultaneously,the expression levels of immune-related genes such as MHC-IIα,MHC-IIβ,CD4,CD8,TNF-αand IL^(-1)βwere up-regulated,demonstrating that it might stimulate humoral and cellular immunological response in turbot.These findings highlight the potential of the bivalent inactivated vaccine for controlling V.scophthalmi and A.salmonicida infections in turbot.

Identification of suitable reference genes for quantitative gene expression analysis in clam Cyclina sinensis under salinity stress and Vibrio infection

The appropriate reference gene is a prerequisite for accurate normalization of gene expression level,and research on suitable reference genes in clam Cyclina sinensis is scarce.To improve the situation,we selected five commonly used housekeeping genes,including β-actin,Elongation factor 1-α(EF1-α),Glyceraldehyde-3-pho sphate dehydrogenase(GAPDH),40S ribosomal protein S18(RPS18),and Tubulin a(TUB-α),then evaluated their expression stability in different adult tissues and under different experimental treatments(salinity stress and Vibrio parahaemolyticus infection).Their expression stability was analyzed by three frequently used programs,geNorm,NormFinder,and BestKeeper.This analysis indicated that multiple genes should be used for normalization,and we concluded that the reference gene combination GAPDH-RPS18-β-actin,should be used for qRT-PCR analysis in different tissues of C.sinensis under normal physiological conditions.For the clams under salinity stress and Vibrio infection,EF1-α-GAPDHRPS18 was recommended as the gene combination for qRT-PCR normalization.TUB-αwas generally poorly ranked by all programs,and should not be used in future studies.This study should provide fundamental support for accurate quantitative gene expression analysis of this species.

Proteomic and Functional Analyses of Outer Membrane Vesicles Secreted by Vibrio splendidus

Vibrio splendidus is an important opportunistic pathogen ubiquitously present in the marine environment,exhibiting virulence to a variety of cultured animals.The extracellular products secreted by V.splendidus are crucial to bacterial survival and virulence.In this study,the secretion of outer membrane vesicles(OMVs)by V.splendidus was determined,purified,and morphologically characterized.The protein composition of OMVs was analyzed by proteomic analysis.The results showed that approximately 120 proteins were contained in these OMVs,including outer membrane proteins,flagellins,ABC transporters,protease,and iron regulation proteins,etc.,which were involved in bacterial motility,formation of biofilms and the cell membrane components,and cellular localization based on their structural molecule activity,passive transmembrane transporter activity,channel activity,neurotransmitter receptor activity,extracellular ligand-gated ion channel activity,glutamate receptor activity,ligand-gated ion channel activity,and transmembrane signaling receptor activity.To explore the biological functions of OMVs in V.splendidus,the effects of OMVs on the bacterial adaption to iron limitation,antibiotic,and the coelomic fluid of the Apostichopus japonicus were confirmed.This study is the first time to show that V.splendidus secretes OMVs,and OMVs carry functional proteins that enhance bacterial survival under various stresses.

Monitoring and analysis of contamination of Vibrio parahaemolyticus and Vibrio alginolyticus in seafood in Haikou

Objective:To investigate the contamination and distribution of Vibrio parahaemolyticus and Vibrio alginolyticus in seafood in Haikou City.Methods:Three types of seafood sold in Haikou from 2020 to 2022 were collected,Vibrio parahaemolyticus and Vibrio alginolyticus were detected according to the National Food Safety Standard Food Microbiological Examination of Vibrio parahaemolyticus(GB 4789.7-2013),and they were identified by real-time fluorescence PCR.The detection of Vibrio parahaemolyticus and Vibrio alginolyticus in different kinds of seafood,different years and different quarters was analyzed.Results:A total of 119 seafood samples were collected.Among them,24 samples were positive with Vibrio parahaemolyticus,with a positive rate of 20.1%;46 samples were positive with Vibrio alginolyticus,with a positive rate of 38.7%.Among various types of seafood,shrimp have the highest positivity rate for Vibrio parahaemolyticus at 50%,while shellfish have the highest positivity rate for Vibrio alginolyticus at 48%.Comparing between monitoring years,the positive rate of Vibrio alginolyticus was the highest in 2021(76.7%),while the positive rate of Vibrio parahaemolyticus was the highest in 2022(25%).Comparing between different quarters,the positivity rate for Vibrio alginolyticus was found to be highest in the second quarter at 80%,while the positivity rate for Vibrio parahaemolyticus was highest in the fourth quarter at 33.3%.There were statistically significant differences(P<0.05)in the positivity rate for Vibrio alginolyticus in different years and quarters,as well as in the positivity rate for Vibrio parahaemolyticus in different types and quarters.Conclusion:Vibrio parahaemolyticus and Vibrio alginolyticus were found in seafood products in Haikou City from 2020 to 2022.It is recommended that relevant departments strengthen supervision to ensure the safety of seafood products consumed by the public.

Amplification and Bioinformatics Analysis of h-ns Gene of Vibrio alginolyticus

[Objectives]To amplify the h-ns gene of Vibrio alginolyticus and analyze it by bioinformatics.[Methods]According to the h-ns gene sequence of V.alginolyticus HY9901,a pair of specific primers were designed and amplified by PCR.[Results]The h-ns gene was 408 bp in length and 135 amino acids were encoded.The predicted theoretical protein molecular weight was about 14.98 kD,and the isoelectric point was 4.99.Protein subcellular localization,SignalP 5.0,TMHMM Server 2.0 and SoftBerry-Psite predictions showed that H-NS was located outside the cell membrane,and the protein was unstable and hydrophobic.There was no signal peptide cleavage site,no transmembrane region and no KEGG metabolic pathway.The amino acid sequence contained three phosphorylation sites,one N-terminal myristoylation site and three microsomal C-terminal target signal sites.Using MEGA 5.0,H-NS phylogenetic tree was constructed by ortho-connection method.The results showed that H-NS of V.alginolyticus was closer to H-NS of Vibrio diabolicus.Using SWISS-MODEL,the three-dimensional structure model of H-NS subunit was simulated,which was similar to the crystal structure of Salmonella typhimurium H-NS1-83.[Conclusions]This study lays a foundation for exploring the regulation mechanism of V.alginolyticus H-NS protein on bacterial virulence in the future.

Effects of Microplastics on Expression of Resistance Genes and Virulence Genes of Vibrio alginolyticus

[Objectives]To study the effects of microplastics on antibiotic resistance genes and virulence genes of Vibrio alginolyticus,so as to provide a certain reference for controlling marine pollution,curbing the spread of environmental antibiotic resistance genes and virulence genes,formulating environmental policies,and maintaining food safety.[Methods]After adding V.alginolyticus into the artificial seawater,they were divided into three groups,namely blank control group(BLK),polyvinyl chloride microplastic group(PVC group)and polyvinyl alcohol microplastic group(PVA group).Aerated culture experiments were carried out,and the effects of microplastics on the expression of resistance genes and virulence genes of V.alginolyticus were studied by PCR and qPCR methods.[Results]The presence of microplastics significantly changed the resistance gene structure of V.alginolyticus.Compared with the control group,the cfxA and cfr resistance genes were detected in the microplastic group.However,only PVC group detected blaZ resistance gene,and only PVA group did not detect aaC resistance gene.In addition,compared with the control group,the expressions of virulence genes in the microplastic group were all down-regulated(P<0.01).[Conclusions]This study provides some reference for curbing the spread of environmental antibiotic resistance genes and virulence genes,formulating environmental policies,and maintaining food safety,but the specific mechanisms of drug resistance and virulence need further research.