降解桔霉素酵母菌的筛选及降解条件的优化

目的 从阿瓦提红葡萄果园土壤以及实验室现有酵母菌株中筛选出一株降解桔霉素(citrinin, CIT)的酵母菌, 并对其降解桔霉素的培养条件进行优化。方法 以YES为基本培养基, 将筛选得到的酵母菌与高产CIT红曲菌M7共培养, 挑选对CIT降解率较高的菌株, 采用形态学和分子生物学进一步对菌株进行鉴定, 采用单因素结合正交试验法优化酵母菌降解CIT的培养条件。结果 得到一株降解CIT能力较高的酵母菌株PT, 经鉴定为库德毕赤酵母, 酵母菌PT降解CIT的最优条件为: 葡萄糖添加量为165 g/L, FeSO4添加量为0.50 g/L, pH为3.0, 于28℃培养13 d, 在此培养条件下酵母菌PT对CIT的降解率为76.78%。结论 采用生物法降解CIT是可行的途径。本研究结果可为微生物脱除CIT的方法提供参考, 同时筛选的酵母菌也可应用于其它发酵食品中。

Screening of yeast for degrading citrinin and optimization of degradation conditions

Objective To select a yeast that degrades citrinin (CIT) from the existing yeast strains in the soil and laboratory of Avati red grape orchard, and to optimize its culture conditions for degrading citrinin. Method Using YES as the basic medium, the selected yeast was co-cultured with high-yielding monasgillus CIT M7, and the strains with high CIT degradation rate were selected. The strain was identified by its morphology and molecular biology. Using single factor method combined orthogonal design, the optimal conditions were studied. Results A strain with strong degradation rate of CIT was obtained as PT, which was identified as Pichia kudriavzevii. Through the optimization of fermentation conditions, the optimum fermentation conditions for the degradation rate of CIT by the strain were as follows: glucose addition was 165 g/L, FeSO4 addition was 0.50 g/L, pH was 3.0, the culture temperature was 28℃, and the culture time was 13 d, under these conditions, the degradation effect of CIT produced by the strain was 76.78%. Conclusion Biodegradation of CIT is a feasible approach. The results of this study can provide a reference for the method of microbial removal of CIT, and the selected yeast can also be applied to other fermented foods.