乳酸菌胞外多糖生物合成的转录调控机制研究

嗜热链球菌广泛应用在发酵乳等食品工业生产中，其胞外多糖（EPS）因独特的理化特性和生理功能而备受青睐。尽管目前对嗜热链球菌EPS生物合成已有一定的了解，改变外界环境和EPS生物合成相关基因的表达都可调控EPS合成，但对其具体的调控机理研究仍偏少，特别是转录调控机制尚未解析。我们推测除EPS基因簇中途径特异性调控因子，嗜热链球菌还存在其它类型调控因子（如全局性调控因子）转录调控EPS合成。基于此，本项目以自行分离的嗜热链球菌S-3菌株所产新EPS生物合成基因簇为研究对象，利用分子生物学和生物信息学等方法，研究EPS基因簇中途径特异性调控因子的转录调控机制。寻找和鉴定与EPS基因簇启动子相互作用的其它类型调控因子，解析其对EPS合成的转录调控机制。本项目从分子水平来阐明嗜热链球菌EPS合成的转录调控网络，深化对乳酸菌EPS生物合成的认识，为提高益生乳酸菌活性功能提供理论基础。

Streptococcus thermophilus is widely used in food industry e.g., fermented milk production. Exopolysaccharide (EPS) in S. thermophilus attracts the attention by its immense physiological function and industrial potential. Despite EPS biosynthesis in S. thermophilushas been studied, the transcriptional regulation of EPS biosynthesis is still unknown. We hypothesize that both pathway-specific transcriptional regulator and other types of regulators (e.g., the global regulators) control EPS biosynthesis at the transcriptional level. This project will focus on EPS biosynthetic gene cluster in S. thermophilus S-3, which could produce a new EPS. Using the methods of molecular biology and bioinformatics, EPS biosynthesis regulated by EPS pathway-specific transcriptional regulator epsA will be elucidated with identifying DNA binding site of EPS promoter (Peps.) Moreover, other types of regulators interacting with Peps will be isolated and identified DNA binding sites. This project will elucidate the transcriptional regulation of EPS biosynthesis in S. thermophilus, which could be an important paradigm for understanding of EPS biosynthesis and regulation in Lactic acid bacteria.