混合培养条件下酿酒酵母菌与毕赤酵母菌的相互影响

摘要

为研究酵母菌混合培养条件下生长状态的变化规律以及相互影响的因素,选取2种酵母菌,酿酒酵母菌(Saccharomyces cerevisiae,Sc) 131和毕赤酵母菌(Pichia fabianii,P.f) 65,考察了初始糖含量、pH值、乙醇体积分数对两菌种混合培养时生长状态的影响,并通过气相色谱-质谱分析方法考察了2种细胞脂肪酸组成的差异性.结果表明,相对于纯培养,混合培养条件下,Pf对Sc产生明显的抑制作用,在低糖和低pH值环境条件下,Sc受抑制作用加剧,当初始糖含量2％时,PflSc(菌体浓度比)为28,pH 3.5时,PflSc达37;在外源添加乙醇时,随着乙醇体积分数的升高,Pf受抑制程度较Sc严重,Sc生长处于相对优势地位,说明Sc较Pf耐乙醇,当乙醇体积分数为12％时,PflSc为0.5.经细胞脂肪酸组成分析,Sc主要为C16的棕榈酸和棕榈油酸,Pf主要为C18的油酸、亚油酸和亚麻酸,混合培养时细胞脂肪酸组成主要为C18型脂肪酸,Pf细胞代谢产生的亚油酸和亚麻酸的积累释放可能是抑制Sc生长的因素之一.实验结果可为进一步从转录组水平研究混合酵母相互影响的机制,以及发酵质量控制提供理论支持.%In order to investigate the changes in the growth state of different yeast species in a mixed culture and the factors affecting their interaction,the effects of initial glucose concentration,pH,and ethanol concentration on the growth of Saccharomyces cerevisiae (Sc) and Pichia fabianii (Pf) when cultured together were investigated,and the differences in the fatty acid composition of both yeasts were also determined by gas chromatography-mass spectrometry (GC-MS).The results showed that Pfhad an obvious inhibitory effect on the growth of Sc during their co-culture under normal conditions.At relatively low sugar concentration and low pH,the growth of Sc was more restrained.At an initial glucose concentration of 2％,the PflSc ratio (the ratio of colony numbers) was 28,and the value was 37 at pH 3.5.With increasing concentration of exogenous ethanol,the growth of Pfwas more restrained than that of Sc,and Sc became dominant,suggesting it to be more resistant to ethanol than Pf.The PflSc ratio was 0.5 under 12％ ethanol stress.The fatty acid composition of Sc mainly consisted of palmitic acid and palmitoleic acid while that of Pf mainly consisted of oleic acid,linoleic acid and linolenic acid.In the mixed culture,the fatty acid composition was dominated by C18 fatty acids,and the linoleic acid and linolenic acid produced by Pfcould inhibit the growth of Sc.These results could provide a basis for further research on the interaction of different yeasts in the mixed culture at the transcriptome level and the quality control of fermented products.