Lager啤酒酵母RLM1基因调控对其抗自溶性能的影响

Regulations of RLM1 gene affect the anti-autolytic ability of lager yeast

摘要:

啤酒酵母的自溶会严重影响啤酒的品质，而酵母的质量也被认为是啤酒酿造的关键因素之一。前期在啤酒酵母自溶的研究中发现细胞完整性途径中重要的转录因子RLM1基因与酵母自溶有密切关系。本研究在啤酒酵母单倍体菌株中对RLM1进行敲除与过表达，发现RLM1敲除后，酵母菌抗自溶性能差，而RLM1过表达则有助于酵母的抗自溶。另外，发现RLM1基因的敲除影响了酵母的抗渗透压性能、细胞壁损伤的耐受性、抗氮饥饿性能和温度耐受性。研究发现细胞壁组装及DNA损伤应答相关基因GAS1的表达随RLM1的过表达与敲除而调整，而CWI途径中其他相关基因的调控方式并没有明显的规律，推测RLM1可能主要影响了CWI途径中GAS1基因的表达，进而提高啤酒酵母在恶劣环境中的抗逆性。此研究结果对于进一步选育抗自溶啤酒酵母以及了解啤酒酵母的自溶机制提供了基础。

关键词:lager啤酒酵母，抗自溶性能，RLM1，细胞壁完整性

Abstract:

The autolysis of brewer’s yeast seriously affects the quality of beer and the quality of yeast is considered as one of the key factors in beer brewing. Previous studies on brewer’s yeast autolysis showed that RLM1 gene, an important transcription factor in cell integrity pathway, is closely related to the autolysis of yeast. In this study, RLM1 was knocked out and overexpressed in a haploid brewer’s yeast. RLM1 disruption resulted in poor anti-autolysis performance of yeast, whereas overexpression of RLM1 contributed to the anti-autolytic ability of yeast. In addition, RLM1 gene knockout affected the osmotic stress resistance, cell wall damage resistance, nitrogen starvation resistance and temperature tolerance of yeast strain. The transcriptional level of GAS1 involved in cell wall assembly and DNA damage response was regulated along with the expression of RLM1, whereas other genes in CWI pathway did not show apparent regularity. RLM1 might mainly affect the expression of GAS1 so as to improve the stress resistance of lager yeast in harsh environment. The result from this study help further understand the mechanism of yeast autolysis and lay a foundation for breeding brewer’s yeast strain with better anti-autolytic ability.

Key words:lager yeast, anti-autolytic ability, RLM1, cell wall integrity