导致黄酒酸败的食果糖乳杆菌的分离、鉴定及其检测条件优化

为提高黄酒中腐败微生物的检测效率,通过传统培养,结合感官评价和总酸变化对导致黄酒酸败的微生物进行分析,同时选择性筛选出目标腐败菌ZH-1和ZH-2,经形态学、生化实验和16S rRNA基因鉴定,并进一步采用单因素和Box-Behnken响应面试验设计方法对目标腐败菌的检测条件进行优化。结果表明:黄酒腐败呈浑浊、异味和总酸升高等特点;分离得到的菌ZH-1和菌ZH-2均鉴定为食果糖乳杆菌,该菌是导致黄酒此类酸败的目标腐败菌,表现为在固体培养基上生长缓慢等特点,采用GB 4789.35—2016《食品微生物学检验乳酸菌检验》的方法,需要9～10 d出结果;对食果糖乳杆菌检测方法优化得到最优的培养条件为:在MRS固体培养基基础上,添加质量分数为0.08%的L-Cys,调节pH值为5.4,临用时加入体积分数为9%的无水乙醇,培养温度为30℃。采用优化后的方法,定量检出时间缩短为3～4 d。

Isolation,Identification and Growth Optimization of Lactobacillus fructivorans Causing Rancidity of Chinese Rice Wine

The aim of this study was to improve the detection efficiency of spoilage bacteria in Chinese rice wine. By using the traditional culture method based on sensory evaluation and the change in total acid, the target spoilage bacteria ZH-1 and ZH-2 were isolated from rancid Chinese rice wine. Furthermore, the spoilage bacteria were identified by their morphological and biochemical characteristics and 16S rRNA gene sequencing. Meanwhile, one-factor-at-a-time method and Box-Behnken design with response surface methodology were employed to optimize the culture conditions for the target spoilage bacteria. The results showed that the rancid Chinese rice wine was muddy with an off odor and increased total acidity. Both ZH-1 and ZH-2 were identified as Lactobacillus fructivorans. The spoilage bacteria grew slowly on solid medium, and it took as long as 9–10 days to culture them using the method described in GB 4789.35-2016; the optimal enrichment conditions for detecting L. fructivorans were MRS agar medium containing 0.08% L-Cys with pH adjusted to 5.4, addition of 9% (V/V) of anhydrous ethanol to the medium immediately before use, and culture temperature 30 ℃. The time required to detect quantitatively L. fructivorans using the optimized method could be shortened by 3–4 days.