地衣芽孢杆菌耐热性的遗传基础

Thermotolerance is one of most important, however not clear in mechanism, physiological and industrial properties in Bacillus licheniformis, an imperative industrial bacterium being applied for manufacturing many benefit products on industrial scales. In order to understand the mechanism of thermotolerance in B. licheniformis, first, the candidate gene(s) for the thermotolerance were cloned by screening genetic library with a genetic complementary method or selected through comparative genomics techniques. Then, the thermotelerance contributed by the candidate genes were exploited by using gene cloning, gene deletion, gene modification and/or gene expression. The key genes and their functional roles associated with thermotolerance were elucidated. Finally, the mechanism for thermotolerance in B. licheniformis was illustrated by analyzing transcription of a certain specific genes, transcriptome, fattic acid components, and intracellular competent solutes as well as growth properties performed in recombinants. The results can not only complement the understanding of thermotolerant nature in the moderate thermophilic bacteria but also push the further researches on genetic improvement of thermotolerance and industrial manufactering properties of industroial strains of B. licheniformis. The results will be of guiding significance for similar researches in elevant prokaryotes.

地衣芽孢杆菌为重要工业细菌，生产多种重要工业产品。耐热性是其重要生理特征与工业应用属性，但机制不明。本项目拟通过遗传互补法和比较基因组法，获得影响（决定）耐热性的候选基因；通过基因克隆、基因删除、基因修饰与基因表达技术等研究并确定候选基因的功能及其与耐热性能之间的关系，获得地衣芽孢杆菌耐热相应的关键基因并确定其功能及功能呈现方式；通过对特定基因的转录特征、重组菌的转录组特征改变、胞壁脂肪酸组成、细胞内相容性溶质组成与含量等研究与分析，解析地衣芽孢杆菌耐热性能形成机制。研究结果可以加深对中度嗜热菌的耐热与适温机理的认知，并为后续理性遗传改良地衣芽孢杆菌工业生产菌株的耐温性能及其工业生产属性奠定重要物质与理论基础。研究结果对相关原核细胞在此方面的研究也一定具有指导意义。

耐热性是地衣芽胞杆菌的重要生理特征和工业应用属性，但其机制尚未阐明。本项目通过基于GC/MS的代谢组学和定量蛋白组学的方法，阐明了菌株Bacillus licheniformis B186的耐热机制，并发现其耐热性与其氨基酸代谢、脂肪酸代谢和分子伴侣等有关。并通过将其中一个关键基因groES进行过表达，提高了B. subtilis WB600的耐热性。此外，还对B. licheniformis B186中的碱性蛋白酶嗜碱突变体的生化特征和耐碱机制进行了初步解析。研究结果可以加深对地衣芽胞杆菌耐热机制的认知，并为后续理性遗传改良地衣芽胞杆菌工业生产菌株的耐热性能和工业生产属性奠定了重要的物质和理论基础。