摘要
【目的】2023年10月,深圳市某养殖基地斜带石斑鱼出现皮肤溃烂、皮下出血及肠炎等症状,明确引发本次斜带石斑鱼(Epinephelus coioides)突发性死亡的致病菌种类及其生物学特性,以筛选出有效抑制病原菌的消毒剂,为溶藻弧菌(Vibrio alginolyticus)感染斜带石斑鱼的科学防治提供理论指导。【方法】利用平板划线法,从患病濒死斜带石斑鱼的病灶组织中分离病原菌,对病原菌形态特征、生理生化特性、系统进化树、毒力基因和耐药基因及药物敏感性进行研究,并对其进行回归感染试验。【结果】从患病斜带石斑鱼组织中分离得到一株溶藻弧菌,命名为菌株SZGP226;系统进化树分析结果显示,该菌与溶藻弧菌HH101307、IB1、Xmb015聚为一支,序列相似性达99.72%;菌株SZGP226可以分解蔗糖、甘露醇、葡萄糖、尿素,氧化酶活性及V-P等生理生化指标鉴定为阳性;同时携带tlh、toxR、ctsA、sto和vpi 5种毒力基因。药敏结果显示,菌株SZGP226耐受氨苄西林、苯唑西林等9种抗生素耐药,并携带qnrB、fl oR、tetC、tetM、qnrD、gyrA、Sul1、SHV和Oxa-24等9种耐药基因。消毒剂筛选结果显示,氢氧化钠对菌株SZGP226的杀菌效果最好、最小抑菌浓度(MIC)为8 mg/mL。回归感染试验表明,菌株SZGP226对斜带石斑鱼具有强致病性,半致死浓度(LC_(50))为1.63×10^(7)CFU/mL,可引起斜带石斑鱼肝脏、肾脏和脾脏发生明显病理性损伤。【结论】溶藻弧菌是引起本次斜带石斑鱼突发性死亡的病原菌,其致病基因包括tlh、toxR、ctsA、sto和vpi,LC_(50)为1.63×10^(7)CFU/mL。氢氧化钠对菌株SZGP226的杀菌效果最好,在养殖开展前可选择氢氧化钠(3 mg/mL)对养殖环境进行消杀清理。
【Objective】In October 2023,skin ulceration,subcutaneous hemorrhage and enteritis appeared in a breeding base of Epinephelus coioides in Shenzhen,China.We clarified the causative organisms that triggered the sudden death of E.coioides and their biological characteristics,and screened the disinfectant that effectively inhibited the causative organisms,with an aim to provide theoretical guidance for the scientific prevention and control of E.coioides infected with Vibrio alginolyticus.【Method】The pathogen of V.alginolyticus was isolated from the diseased tissues of the dying E.coioides by streak plate method,the morphological characteristics,physiological and biochemical properties,phylogenetic tree,virulence genes and resistance genes as well as drug sensitivity of the pathogen were investigated,and regression infection tests were carried out.【Result】A dominant strain was isolated from the diseased tissues of E.coioides and named as strain SZGP226.The results of phylogenetic analysis showed that,the sequence of strain SZGP226 was homologous to V.alginolyticus HH101307,IB1 and Xmb015,with a similarity of 99.72%.The strain was identified as positive in physiological and biochemical indexes such as sucrose,mannitol,glucose,urea,oxidase activity and V-P,and it also carried five virulence genes,namely,tlh,toxR,ctsA,sto and vpi.The results of drug sensitivity showed that strain SZGP226 was resistant to 9 antibiotics like ampicillin and benzoxacillin,and carried 9 resistance genes including qnrB,fl oR,tetC,tetM,qnrD,gyrA,Sul1,SHV,and Oxa-24.The screening results of disinfectants showed that,sodium hydroxide had the best bactericidal effect,and its minimal inhibition concentration(MIC)was 8 mg/mL.The regression infection test showed that strain SZGP226 was strongly pathogenic to the E.coioides,with a LC_(50)of 1.63×10^(7)CFU/mL,and it could cause obvious pathological damage to the liver,kidney and spleen of the E.coioides.【Conclusion】V.alginolyticus was the main pathogenic bacterium for the sudden death of the E.coioides,and its causative genes included tlh,toxR,ctsA,sto and vpi,and the LC_(50)was 1.63×10^(7)CFU/mL.Sodium hydroxide(3 mg/mL)showing the best bactericidal effect on strain bactericidal effect could be selected to clean up the culture environment before aquaculture was carried out.
作者
史磊
罗伟杰
黄瑜
雷美华
喻大鹏
简纪常
黄浦江
SHI Lei;LUO Weijie;HUANG Yu;LEI Meihua;YU Dapeng;JIAN Jichang;HUANG Pujiang(College of Fisheries,Guangdong Ocean University/Guangdong Key Laboratory of Aquatic Animal Disease Control and Healthy Culture/Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes,Zhanjiang 524088,China;Shenzhen Fisheries Development Research Center,Shenzhen 518067,China;Shenzhen Institute of Guangdong Ocean University,Shenzhen 518120,China)
出处
《广东农业科学》
CAS
2024年第7期91-104,共14页
Guangdong Agricultural Sciences
基金
国家自然科学基金(U20A2065)。
关键词
斜带石斑鱼
溶藻弧菌
16S
rRNA
药敏试验
基因检测
Epinephelus coioides
Vibrio alginolyticu
16S rRNA
drug sensitivity test
virulence gene
