广东省南美白对虾豚鼠气单胞菌的分离鉴定

Isolation and characterization of Aeromonas caviae from Penaeus vannamei Boone( Litopenaeus vannamei) in Guangdong Province

广东省某养殖场南美白对虾于2012年突发传染病,为确定该病病原并对其进行有效防制,特利用分子生物学技术对病原进行了分离鉴定。结果从发病南美白对虾分离纯化到1株优势菌ZHBX12016,将该菌人工浸浴感染南美白对虾,5 d后南美白对虾死亡率达95%,且发病对虾临床症状与自然病例相似,人工注射感染测得其半数致死量LD50为6.43×103cfu/mL。该菌革兰氏染色阴性,短杆状;对半乳糖、蔗糖、甘露醇、葡萄糖产气、精氨酸双水解酶,赖氨酸脱酸酶,葡萄糖酸盐的生化反应性与豚鼠气单胞菌（Aeromonas caviae）（synonym Aeromonas punctata）生化反应结果相同。用聚合酶链式反应（PCR）技术扩增该菌16S rD NA序列进行测序和生物信息学分析,结果显示：分离菌株与豚鼠气单胞菌（Aeromonas caviae）相似性达97.7%-100%之间,在系统发育树上聚为同一分支。综合该菌形态学、致病性、生理生化和16S rRNA基因分析结果,将其鉴定为豚鼠气单胞菌（Aeromonas caviae）。药敏试验结果表明分离菌株对氯霉素、土霉素、丁胺卡那、呋喃唑酮等高度敏感。

An infectious disease outbreak in Penaeus vannamei Boone（ Litopenaeus vannamei） occurred in Guangdong Province in 2012. For the diagnosis,and effective prevention and control of this disease,the pathogen was isolated and characterized via molecular biology. One isolate of Aeromonas caviae（ ZHBX12016） was isolated. This strain could induce symptoms of natural disease in Penaeus vannamei and resulted in 95% mortality in 5 days by immersion infection,and with LD50 of 6. 43 × 103 cfu/m L via muscle injection. The isolate was Gram-nagative straight rod. Biochemical characterization of Galactose,Sucrose,Mannitol,Glucose,Arginine dihydrolase,Lysine decarboxylase and gluconate showed that the isolate was similar to Aeromonas caviae isolated from other aquatic animals. The 16 S r DNA gene was amplified by polymerase chain reaction（ PCR） and sequencing. Analysis of 16 S rRNA gene showed that the isolate shared97. 7%- 100% identity with A. caviae. The phylogenitic tree derived from 16 S r DNA gene of Aeromonas showed that the isolate and A. caviae clustered into the same branch. Based on morphological,biochemical and physiological responses,pathogenicity and 16 S rRNA gene analysis,the isolate was identified as A.caviae. The antibiotic sensitivity test showed that the strain ZHBX12016 was hypersensitive to chloramphenicol,terramycin,amikacin and furazolidone.