针对分离筛选的一株产胞外多糖菌株TH21-44,通过形态观察、生理生化试验和16SrRNA基因系统发育分析进行种属鉴定,采用单因素和响应面法优化胞外多糖的发酵条件,并分析胞外多糖的乳化性能.结果表明,菌株TH21-44为副球菌(Paracoccus sp.);最佳产糖条件为pH7.1、接种量6.1%、温度28℃、葡萄糖7.2 g/L、酵母浸粉3.0g/L、K2HPO4·3H2O 0.3 g/L、MgSO4·7H2O 0.05 g/L及丙酮酸钠0.3 g/L,该条件下胞外多糖产量为188.89 μg/mL,是优化前的3.18倍;所产胞外多糖具有良好的乳化性能,对葵花油24 h时的乳化能力为69.62%,优于吐温80.该研究为微生物胞外多糖的菌物资源开发和应用提供了依据和参考.
An exopolysaccharides(EPS)-producing strain TH21-44 was identified based on the morphological observation,physiological and biochemical tests,and 16S rRNA gene-based phylogenetic analysis.Further-more,the fermentation conditions of the strain for the production of EPS were optimized by single-factor and re-sponse surface methods,and the emulsification performance of the EPS was evaluated.The strain TH21-44 was identified as Paracoccus sp.The optimal fermentation conditions for EPS production were pH7.1,inoculum size of 6.1%,temperature of 28 ℃,glucose of 7.2 g/L,yeast extract of 3.0 g/L,K2HPO4·3H2O of 0.3 g/L,MgSO4·7H2O of 0.05 g/L,and sodium pyruvate of 0.3 g/L.Under these conditions,the EPS yield was 188.89μg/mL,which was 3.18 times as high as that of before optimization.The produced EPS maintained 69.62%emulsification capacity for sunflower oil after 24 h,demonstrating the emulsification performance superior to Tween 80.The findings provide the bacterial strain resources and theoretical references for the development and application of microbial exopolysaccharides.