沙雷氏菌属新种YD25中环脂肽类化合物与灵菌红素生物合成的共调控机制研究

The cyclic lipopeptide Serrawettin W2 (W2) and the red-pigmented prodigiosin (PG) generated by Serratia act as antibacterial and antitumor agents, which are of great significance in the applications of bio-control and medicine. In the previous study, we have isolated a strain YD25 that can co-produces W2 and PG. On the basis of polyphasic characterization data obtained, the strain YD25 is proposed as a new species for which the name Serratia surfactantfaciens sp. nov. The genome sequencing and preliminary studies indicate that there is a potential co-regulation of W2 and PG biosynthesis. However, so far there is no study on the co-regulation mechanism of W2 and PG. In this proposal, the relationship between regulatory factors of W2 and PG co-regulated pathway will be focused taking advantages of the information that we obtain gene function positioning by using gene targeting technology. Studies on the molecular mechanisms and related regulatory pathway will be performed by the transcriptome analysis, qRT-PCR, EMSA, and CHIP technologies, which will benefit the illustration of the co-regulation mechanism of W2 and PG. The results obtained in this study will fill up the gap of W2 and PG co-regulation mechanism, and enrich the co-regulation mechanism of the biosurfactant and PG, which also will support the further improvement of the production of secondary metabolites in Serratia.

沙雷氏菌产生的环脂肽Serrawettin W2(W2)和灵菌红素(PG)可作为抗菌、抗肿瘤制剂在生防、医药领域具有重要应用价值。本课题组筛选到一株独特的能同时产W2和PG的菌株YD25，经多相分类法鉴定其为沙雷氏菌属新种，这是首次报道W2和PG同时产生的菌株。基因组测序及前期研究表明W2和PG生物合成存在潜在的共调控作用，但这种新颖的W2和PG生物合成共调控机制尚未见报道。本研究利用基因打靶技术对W2和PG生物合成调控通路中相关共调控因子进行基因功能定位，明确调控因子之间相互关系；利用转录组学分析、qRT-PCR、EMSA、CHIP等技术对调节基因的作用方式进行研究，揭示其分子作用机理和相关调控通路，阐明W2和PG生物合成的共调控机制。本课题的完成将填补W2和PG共调控机制研究的空白，补充沙雷氏菌中表面活性剂和PG共调控机制的类型，为提高沙雷氏菌次级代谢产物产量的定向工程改造提供新靶点。

沙雷氏菌产生的环脂肽Serrawettin W2（W2）)和灵菌红素（PG）可作为抗菌、抗肿瘤制剂在生防、医药领域具有重要应用价值。本项目以沙雷氏菌属新种Serratia. surfactantfaciens YD25为研究对象，对菌株中存在的新颖的W2和PG的生物合成代谢共调控机制进行了深入研究。完成了针对沙雷氏菌属基因功能表征与定位的CRISPR特异性完整体系的搭建；对W2和PG生物合成调控通路中相关共调控因子进行了基因功能定位，明确了调控因子之间相互关系；揭示了在菌株YD25中AI-2型群体感应调控系统LuxS调控因子对次级代谢产物生物合成调控起到主要作用；此外，菌株的代谢受到温度调控机制的影响，温度变化会影响Cpx二元调控系统和共调控因子SlyA的表达，CpxR的激活进而促进另一共调控因子HexS的表达；同时明确了与提高沙雷氏菌次级代谢产物产量相关的负调控因子HexS，获得了环脂肽类化合物W2和PG的定向高产菌株，为新型抗生素或抗肿瘤药物的研发提供了材料；进一步发现了在菌株YD25中与W2和PG前体物质合成相关的合成酶基因pswP，与两者转录后共调控相关的因子csrA，和其他与转录共调控相关的基因gumB、pigP、slyA、lsrR和soxR。本项目的完成，阐明了W2与PG两种次级代谢产物生物合成共调控作用方式和分子机理，填补了对两者共调控途径研究的空白，完善了沙雷氏菌中表面活性剂和灵菌红素的共调控机制，为提高沙雷氏菌次级代谢产物产量的定向工程改造提供了新靶点。