鮰鱼肌肉组织中不动杆菌的分离及鉴定

将鮰鱼在4℃冷库中取得背部肌肉组织,进行真空包装,在4℃冰箱中贮藏7 d,分离得到2株细菌,分别编号为by 7-2、bs 7-3,进行细菌形态学观察、革兰氏染色、生化鉴定、16S rDNA测序及负染等。结果表明:菌株by 7-2在LB琼脂培养基上为圆形、湿润、白色菌落,菌株bs 7-3在LB琼脂培养基上为圆形、湿润、乳白色菌落;革兰氏染色镜检表明,2株细菌均为革兰氏阴性菌;负染结果表明,by 7-2为短杆菌,bs 7-3为长杆菌,且二者均无鞭毛;生化鉴定结果显示,菌株by 7-2和bs 7-3硝酸盐还原、精氨酸双水解酶、乙酰胺酶、分解木糖、分解麦芽糖、分解甘露醇、DNA酶和氧化酶实验均为阴性,菌株bs 7-3的利用柠檬酸盐和O-F实验为阳性,菌株by 7-2利用柠檬酸盐和O-F实验为阴性;进一步通过16S rDNA测序及系统发育树分析显示,by 7-2与约翰逊不动杆菌(Acinetobacter johnsonii)亲缘关系最近,相似度达99.90%,bs 7-3与抗辐射不动杆菌(Acinetobacter radioresistens)亲缘关系最近,相似度达99.79%。因此,菌株by 7-2为约翰逊不动杆菌,bs 7-3为抗辐射不动杆菌。

Isolation and Identification of Acinetobacter from the Muscle of Channel Catfish (Ictalurus punctatus)

Two bacterial strains, designated by 7-2 and bs 7-3, were isolated from the back muscle of channel catfish vacuum packaged at 4 ℃ for seven days. They were identified by morphological observation and Gram staining, biochemical tests, 16S rDNA sequencing, and negative staining. Strain by 7-2 formed round, moist, white colonies on LB agar medium, and strain bs 7-3 formed round, moist, milky white colony colonies on LB agar medium. Both bacteria were Gram-negative bacteria, and strain by 7-2 was a short rod-shaped bacterium, while strain bs 7-3 was a long rod-shaped bacterium. Both strains had no flagella and were negative for nitrate reduction, arginine dihydrolase, acetamidase, xylose decomposition, maltose decomposition, mannitol decomposition, DNase and oxidase. Strain bs 7-3 was positive for citrate and O-F test, while strain by 7-2 was negative. 16S rDNA sequencing and phylogenetic tree analysis showed that by 7-2 had the closest relationship with Acinetobacter johnsonii (99.90%); bs 7-3 had the closest relationship with Acinetobacter radioresistens (99.79%). Therefore, by 7-2 was identified as Acinetobacter johnsonii, and bs 7-3 as Acinetobacter radioresistens.