产胞外多糖酵母菌株的筛选鉴定及发酵产糖

【目的】微生物胞外多糖大多具有良好的功能和特性,但对酵母胞外多糖的研究甚少。本研究从自然界中筛选出产胞外多糖的酵母菌株,并对其发酵产糖条件进行初步研究。【方法】利用平板涂布法从自然界中分离得到酵母菌株,苯酚硫酸法测定菌株胞外多糖的产量,筛选出胞外多糖高产菌株,并对其进行5.8SrDNA分类鉴定,最后优化其产糖培养基组成。【结果】对从葡萄、蜜枣、土壤样品中分离得到的132株酵母进行筛选,最终得到3株高产胞外多糖的酵母菌株Z14、Z20和L25。经5.8S rDNA序列测定及系统发育分析,从左优红葡萄中分离得到的Z14和Z20与东方伊萨酵母(Issatchenkia orientalis)处于同一分支,相似性达到99%以上;从落叶松近表层土壤分离得到的L25与土生隐球酵母(Cryptococcus humicolus)处于同一分支,相似性为98.8%。经优化,利于Z20胞外多糖合成的最优发酵培养基配方为:葡萄糖8%,(NH4)SO40.2%,KH2PO40.1%,酵母浸粉0.1%,CaCl20.01%。在初始pH6.0,发酵温度28℃,摇床转数160 r/min条件下,在此培养基中发酵4 d后胞外多糖产量可达2.046 g/L,比复筛时的产量1.137 g/L提高了79.9%。【结论】文献已报道某些属的酵母可以生产胞外多糖,经本文研究发现Issatchenkia属的酵母也可以合成胞外多糖,并且改变基础产糖培养基的成分可以显着提高Z20胞外多糖的产量。

Screening and identification of exopolysaccharide-producing yeasts

Objective] Most of microbial extracellular polysaccharide(EPS) has the favorable functionality and peculiarity,but little research has been done about EPS that were synthesized by yeasts.Screening of EPS-producing yeasts and studies on the optimal culture composition are the main purpose of this study.Methods] Yeasts were obtained by screening from natural samples using spread-plate method,Yield of EPS synthesized by yeasts was estimated by phenol-sulfate acid method,Based on 5.8S rDNA sequence determinat...