冷藏罗非鱼优势腐败菌的鉴定及其特征

Characterization and identification of dominated spoilage organism of chilled tilapia

通过表型和细胞脂肪酸组成特征等方面，对0，5，10℃冷藏养殖罗非鱼货架期终点的优势菌进行定性和定量研究。结果显示，0，5，10℃冷藏养殖罗非鱼货架期终点时，优势菌群比例分别为80．7％，68．1％，57．5％，可确认假单胞菌为0～10℃贮藏罗非鱼的优势腐败菌，包括荧光假单胞菌、铜绿假单胞菌、恶臭假单胞菌、产碱假单胞菌和其他假单胞菌。优势菌特征测试表明，假单胞菌在营养琼脂和胰酶解大豆胨琼脂培养基上菌落圆状隆起，边缘整齐，透明，无色；革兰氏阴性杆菌，极生单鞭毛，具有运动性，大小为（0．5～0．7）μm×（1．6～3．2）μm；氧化酶反应为阳性，不能利用海藻糖、棉子醇和甘露醇等；最优势菌荧光假单胞菌中直链、支链、环丙基、羟基脂肪酸等被检出，富含单不饱和脂肪酸（50．18％），主要脂肪酸有16：1ω7c，iso-15：0，16：0，17：1ω8c，比例分别为26．16％，14．83％，7．96％，3．94％。

Dominated spoilage organisms isolated from cultured Tilapia at the end of shelf life during storage at 0,5,10℃ were qualitatively and quantitatively investigated by phenotypic tests and whole-cell fatty acid composition. The results showed that dominated spoilage organisms in tilapia were 80.7% ,68.1% ,57.5% at the end of shelf life of tilapia stored at 0, 5,10 ℃, respectively. Dominated strains were identified as Pseudomonas spp. including P. fluorescens, P. aeruginosa, P. putida, P. alcaligenes, etc. based on phenotypic tests. Colonies of Pseudomonas spp. on nutrition agar and trypticase soy broth agar were global apophysis, trim side, smooth clarity, aehromatism; The cells were gram negative rod （0.5 -0.7 ）μm×（ 1.6 - 3.2 ）μm and motile by means of polar flagellum ; Positive for oxidation, but strains can＇t assimilated trehalose, mannitol and raffinose, ect. A variety of acids were detected in most dominated bacteria of Pseudomonas fluorescens, including branched and straightchained acids, cyclopropane, and hydroxy acids. The unsaturated fatty acids were predominated fatty acid（ 50. 18% ）, which main fatty acids were 16 ： 1 ωTc,iso-15 ： 0,16 ： 0,17 ： 1 ω8c, its contents were 26.16 %, 14.83% ,7.96% ,3.94% , respectively.