纳豆芽胞杆菌维生素K2代谢调控生物膜形成机制

作为一种能够促进凝血酶原产生、增加骨骼密度以及修复损伤细胞线粒体的人体必需维生素，维生素K2在食品行业具有非常广阔的应用前景。纳豆芽胞杆菌维生素K2的合成量低限制了它的应用。前期研究发现维生素K2的合成代谢有利于纳豆芽胞杆菌生物膜的形成，且形成的生物膜可以显著促进维生素K2的合成。为探究维生素K2代谢调控生物膜形成的作用机理，本项目拟以纳豆芽胞杆菌为研究对象，结合反义RNA抑制、定点突变技术构建维生素K2代谢合成酶基因沉默突变株，对其生物膜形成差异进行比较；结合细胞膜壁特性及群体感应系统分析，揭示维生素K2代谢调控对生物膜形成的影响；以RNA-Seq转录组测序、David和KEGG聚类分析为手段，对其调控机制进行解析。本项目旨在探究纳豆芽胞杆菌维生素K2代谢调控生物膜形成的作用机制，以期为进一步促进纳豆芽胞杆菌维生素K2合成和解析群体感应信号系统介导的生物膜形成机制提供理论参考。

As a kind of essential vitamins for human body, vitamin K2 has many important physiological functions such as promote the generation of prothrombin, increase synthesis of osteocalcin, repair the mitochondria of damaged cells. Thus it has a very broad application prospect in food industry. However, the application of vitamin K2 by Bacillus subtilis natto was limited by the low synthesis. Previous studies found that the metabolism of vitamin K2 of Bacillus subtilis natto was beneficial to biofilm formation. In addition, the formed biofilm could promote the synthesis of vitamin K2 significantly. To explore the mechanism of biofilm formation regulated by the metabolism of vitamin K2 of Bacillus subtilis natto, we construct different mutant strains whose genes of enzymes involved in vitamin K2 synthesis were silenced by antisense RNA and site-directed mutagenesis. To study the effect of vitamin K2 metabolism on the biofilm formation, the differences in biofilm formation of mutants were compared combined with analysis of membrane properties and quorum-sensing system. Finally, the regulatory mechanism was disclosed by RNA-Seq transcriptome sequencing, David and KEGG analysis. The aim of this project is to explore the mechanisms of biofilm formation regulated by the metabolism of vitamin K2 of Bacillus subtilis natto, and provide theoretical reference for promoting the synthesis of vitamin K2 in Bacillus subtils natto and analyzing the mechanism of biofilm formation mediated by quorum sensing system.