冷藏罗非鱼特定腐败菌的鉴定和生长动力学

对0、5和10℃冷藏养殖罗非鱼货架期终点的特定腐败菌进行定性和定量研究，并建立特定腐败菌的生长动力学模型。实验结果表明，0、5和10℃冷藏养殖罗非鱼货架期终点时，假单胞菌占总茵数比例分别为80．7％、68．1％和57．5％。该类菌在营养琼脂和胰酶解大豆胨琼脂培养基上茵落圆状隆起，边缘整齐，透明，无色；菌体为革兰氏阴性杆菌，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；直链、支链、环丙基和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16：10J7c、iso-15：0、16：0和17：Ic08c，比例分别为26．16％、14．83％、7．96％和3．94％；Riboprinter测试其核糖体型为56-S-7。采用修正的Gompertz方程拟合假单胞菌生长模型表明，0、5和10℃冷藏过程延滞时间分别为（59．63±61．88）、（7．25±24．06）和（3．95±9．83）h；最大比生长速率分别为（0．02±0．00）、（0．04±0．00）和（0．08±0．01）／h。

Identification and growth dynamics of specific spoilage organisms in chilled tilapia

The specific spoilage organisms （SSO） in cultured tilapia at the end of shelf life during storage at 0, 5 and 10℃ were qualitatively and quantitatively investigated, and the growth model of SSO was established. The results indicated that the percentage of Pseudo- monas spp. in total bacteria in the tilapia were 80.7% ,68.1% and 57.5% at the end of shelf life of tilapia stored at 0, 5 and 10 ℃, respectively. Colonies of Pseudomonas spp. on nutrition agar and trypticase soy broth agar were circular apophysis with smooth edge, transparent and colour- less; 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 the strains could not assimilated trehalose, mannitol and raffinose, etc. A variety of acids were detected in these organisms, including branched and straight-chained acids, cyclopropane, and hydroxy acids. Unsaturated fatty acids comprised a large part of all fatty acids （50.18%）, and the major ones were 16 ： lco7c, iso-15： 0, 16 ： 0 and 17 ： 1ω8c, which were 26.16%, 14.83%, 7.96% and 3.94% of total fatty acids, respec- tively. The type of ribosome of these bacteria was 56-S-7, as tested by Riboprinter. The growth dynamic for Pseudomonas spp. was fitted by modified Gompertz equation. The results showed that lag time reached（59.63±61.88）, （7.25±24.06） and （3.95±9.83）h during storage at 0, 5 and 10 ℃, respectively. The maximum specific growth rates for Pseudomonas spp. were （0.02±0.00）h-1 , （0.04±0.00）h-1 and （0.08±0.01）h-1at 0, 5 and 10 ℃, respectively.