一株高产乙偶姻芽孢杆菌菌株筛选及发酵条件优化

Screening of a Bacillus Strain with High Acetoin-producing Ability and Optimization of Its Fermentation Conditions

摘要:

为缓解乙偶姻的生产对石油的依赖，本研究利用分光光度法从浓香型大曲中筛选得到一株高产乙偶姻（Acetoin，ACT）且对酸度、乙醇具有较大耐受性的芽孢杆菌，经形态学观察、生理生化试验及分子生物学技术鉴定为贝莱斯芽孢杆菌。对该菌株pH、温度、装液量、接种量、转速等5个发酵条件进行单因素试验和正交试验，由极差分析可知，各因素对ACT产量的影响大小依次为pH>温度>装液量>接种量>转速。对影响ACT产量前3的因素进行响应面试验，得出最佳发酵条件为：pH 5.46，温度37.30 ℃，装液量49.20 mL，接种量5%，转速210 r/min。在此条件下菌株摇瓶发酵ACT的平均产率为25.60 g/L，比优化前菌株ACT产率18.37 g/L提高了39.36%。本研究对微生物生产ACT的生产策略有一定指导作用，且筛选所得芽孢杆菌在提升白酒风味方面有巨大应用潜力。

Abstract:

In order to alleviate the dependence of acetoin production on petroleum, a Bacillus strain with high yield of acetoin, greater tolerance to acidity and ethanol was screened from Nongxiang Daqu by spectrophotometry in this study. The strain with was identified as Bacillus velezensis through morphological observations and physiological and biochemical tests and by the molecular biology technique. The single factor tests and orthogonal experiments were carried out on the five fermentation conditions of the strain, including pH, temperature, liquid loading volume, inoculation amount and shaking speed. According to the range analysis, the extent of the influence of each factor on acetoin production was in the order of pH>temperature>liquid loading volume>inoculum amount>shaking speed. Response surface methodology was used to optimize the first three fermentation conditions, and the optimal fermentation conditions were obtained as follows: pH 5.46, temperature 37.30 ℃, liquid loading volume 49.20 mL, inoculum amount 5%, and shaking speed 210 r/min. Under these conditions, the average yield of acetoin by shake-flask fermentation of the strain was 25.60 g/L, which was 39.36% higher than that before optimization (18.37 g/L). The research provides guidance on the strategy of microbial production of acetoin, and the selected Bacillus velezensis has great application potential in enhancing the flavor of Baijiu.