丝氨酸对葡萄酒酿造过程中酿酒酵母产H2S的形成研究

为探究丝氨酸对葡萄酒酿造过程中酿酒酵母产H2S的影响，以自主筛选的本土酿酒酵母32y12为研究对象，分别在正常氮源（300 mg N/L）和低浓度氮源（150 mg N/L）条件下，比较了外源丝氨酸的添加对酿酒酵母32y12发酵过程中产H2S的影响。结果显示，相对于正常氮源水平，低氮条件下外源添加140.8 mg/L（5倍）和281.5 mg/L（10倍）丝氨酸时，H2S释放量显著增加，分别达到573.1 μL/L和798.6 μL/L。为了进一步研究酵母自身丝氨酸合成对H2S产生的影响，借助Cre-Loxp系统敲除了丝氨酸合成关键基因SER33，结果发现在不同氮源水平下，基因SER33的敲除均显著降低H2S产量（P＜0.05），并且外源添加不同浓度丝氨酸也并不会显著增加基因SER33敲除菌株的H2S释放量（P＞0.05）。该结果为工业生产中针对低氮葡萄原料选择发酵助剂提供了理论支持。

Effect of serine on the H2S formation during wine fermentation of Saccharomyces cerevisiae

In order to investigate the effect of serine on H2S production in Saccharomyces cerevisiae during wine brewing process, using the native S. cerevisiae 32y12 screened independently as research object, under the normal nitrogen source (300 mg N/L) and low concentration nitrogen source (150 mg N/L), the effect of adding exogenous serine on S. cerevisiae 32y12 producing H2S during fermentation was compared. The results showed that compared with the normal nitrogen source, under low nitrogen concentration, adding exogenous serine could significantly increase H2S production, which could achieve 573.1 μl/L and 798.6 μl/L in adding serine 140.8 mg/L (5 times) and 281.5 mg/L (10 times), respectively. For further research the effect of yeast synthesis serine on H2S production, the key gene SER33 of serine synthesis was knocked by Cre-Loxp system. Results showed that under different levels of nitrogen, the knockout of gene SER33 decreased H2S production significantly (P＜0.05), and the adding different concentrations of serine could not increase H2S production of strains knocked gene SER33 significantly (P＞0.05), which provided the theoretical support for fermentation agent selection of grape raw materials with low concentration nitrogen in industrial production.