以大豆糖蜜为原料高产乙醇酵母的筛选鉴定及其发酵特性研究

从大豆糖蜜中进行高产乙醇酵母的筛选和鉴定,并对其发酵特性进行研究。从大豆糖蜜中通过菌种的富集分离,TTC平板法初筛,耐乙醇能力及乙醇发酵能力的测定,筛选出一株乙醇产量达9.07%(V/V)的菌株P14。通过个体形态、菌落特征、生理生化及26S rDNA D1/D2区序列分析将菌株P14鉴定为酿酒酵母。研究了大豆糖蜜浓度及添加氮源和无机盐对酿酒酵母P14发酵生产乙醇的影响及酿酒酵母P14对大豆糖蜜中低聚糖的利用,结果表明大豆糖蜜浓度、添加氮源和无机盐对乙醇发酵影响显著,最佳的大豆糖蜜浓度为40%,添加氮源为1.2 g/L的蛋白胨;补加的无机盐为0.4 g/L MgSO4。在此培养基中发酵72 h后,糖蜜中90.10%的葡萄糖,91.23%的蔗糖,92.56%的棉籽糖和96.97%的水苏糖被酵母利用。因此大豆糖蜜中筛选出来的酿酒酵母P14具有较强的利用大豆糖蜜中的大豆低聚糖发酵产生乙醇的能力。

Screening, Identification, and Fermentation Characteristics of High-yielding Ethanologenic Yeasts and Their Utilization of Soybean Molasses as A Raw Material

A strain of yeast producing a high ethanol yield was isolated from soybean molasses, and its fermentation characteristics were studied. The strain P14, with an ethanol yield of up to 9.07% (V/V), was isolated from soybean molasses by enrichment and isolation of strains, preliminary screening using a 2,3,5-triphenyl tetrazolium chloride (TTC) assay, and determination of ethanol tolerance and fermentation capacity. Strain P14 was identified as Saccharomyces cerevisiae on the basis of morphological characteristics, colony morphology, physiological and biochemical tests, and sequence analysis of the D1/D2 region of 26S rDNA. The effects of the concentration of soybean molasses, and addition of a nitrogen source and mineral salts on ethanol fermentation by Saccharomyces cerevisiae P14, as well as the utilization of oligosaccharides in soybean molasses by Saccharomyces cerevisiae P14 were studied. The results showed that soybean molasses concentration, and addition of a nitrogen source and mineral salts significantly influenced ethanol fermentation. The following conditions were determined to be optimal: 40% soybean molasses concentration, 1.2 g/L of peptone, and 0.4 g/L of added MgSO4. After fermentation for 72 h in this medium, 90.10% of glucose, 91.23% of sucrose, 92.56% of raffinose, and 96.97% of stachyose in molasses had been utilized by the yeast. Therefore, the Saccharomyces cerevisiae strain P14 identified from soybean molasses has a relatively strong capacity to produce ethanol by fermentation, using soy oligosaccharides present in soybean molasses.