产胞外多糖酵母菌的分离鉴定及其发酵条件优化

为筛选新型高产胞外多糖(exopolysaccharides,EPS)的酵母菌株,满足工业化生产的要求,该研究利用WL选择培养基和产糖基础培养基筛选出高产EPS的酵母菌,通过形态特征观察、生理生化试验和18S rDNA技术对其进行鉴定,并利用响应面方法对菌株产胞外多糖条件进行优化。结果表明,从土壤中筛选得到一株高产EPS的酵母菌,经鉴定,该酵母菌为近粉红锁掷孢酵母(Sporidiobolus pararoseus),命名为S.pararoseus PFY-Z1,当葡萄糖17.34 g/L、硫酸镁1.98 g/L、初始pH值5.3时,EPS的含量为(6.74±0.13)g/L,是优化前的1.63倍。不仅为EPS的生产提供菌种来源,也为今后利用S.pararoseus大规模生产EPS提供理论基础。

Isolation and Identification of An Exopolysaccharide-producing Sporidiobolus and Optimization of Fermentation Process

In order to screen new high-yield exopolysaccharides(EPS)yeast strains to meet the requirements of industrial production,the EPS-producing of strain was screened by WL selected medium and sugar medium.The strain was identified according to morphological,biochemical and 18S rDNA sequence methods.Response surface methodology was adopted to optimize the EPS-producing condition parameters.The results showed that a Sporidiobolus strain with high EPS-producing ability was isolated and which was identified as Sporidiobolus pararoseus,and named it S.pararoseus PFY-Z1.The optimum fermentation condition was found to consist of glucose 17.34 g/L,MgSO41.98 g/L,and initial pH 5.3.The bacterium grown in the optimized medium yielded(6.74±0.13)g/L of EPS,which was increased by 1.63 compared to that obtained using the unoptimized condition.This study not only provided the source of bacteria for EPS production,but also provided a theoretical basis for the large-scale production of EPS using S.pararoseus in the future.