基于信号分子研究群体感应对河豚共栖菌代谢产河豚毒素的调控机制

Tetrodotoxin is the main cause of poisoning of eating pufferfish, and is also a kind of neurotoxins with high value in the field of scientific research and medical treatment. Now people know it can be produced by microorganism, but still know very little about the biosynthetic pathway. In our previous work, a Bacillus vallismortis TL-1 which can produce tetrodotoxin were isolated from the wild puffer fish. We found that toxin-producing ability of B. vallismortis TL-1 may depended on quorum sensing. In this study, we will isolate and identify the signaling molecules in the metabolite of microorganism, and we will study how dose quorum sensing regulate B. vallismortis TL-1 producing tetrodotoxin based on signal molecule. From this study, we can learn tetrodotoxin produced by microorganism from the level of fermentation metabolism to the level of chemistry molecules regulation, which will lay the rationale for the further study of tetrodotoxin produced by biosynthetic pathway, and give the theory instruction for the practice of controlling or using microorganism fermentation to produce tetrodotoxin.

河豚毒素是食用河豚中毒的主要原因，同时又是一种极具科研和药用价值的神经毒素。现有研究已证实，微生物代谢是河豚毒素的重要来源之一。但对于微生物代谢产河豚毒素的生物途径及相应调控机制，人们仍知之甚少。在前期工作中，我们从鄱阳湖野生河豚鱼体内筛选到多株共栖微生物，其中一株Bacillus vallismortis TL-1具有产河豚毒素能力；进一步研究发现其产河豚毒素能力可能受到种内/种间群体感应的调控。在本课题中，我们将从微生物群体感应的角度，对TL-1（产毒菌）及另一株河豚共栖菌Pseudomonas sp. TL-2（非产毒菌）代谢产物中的信号分子进行分离鉴定，并研究这些信号分子对菌株TL-1产毒行为的具体调控作用。该工作将为进一步揭示河豚毒素的合成代谢途径奠定理论基础；为实践中控制与河豚毒素相关的食物中毒，或指导河豚毒素的发酵利用提供理论指导。

本项目聚焦两个目标，即对两个假说的论证：1 通过河豚共栖菌B. vallismortis TL-1 代谢产物中可能种内信号分子的分离鉴定和种内信号分子对B. vallismortis TL-1 代谢产河豚毒素的调控研究，来论证B. vallismortis TL-1 代谢产河豚毒素行为是否受到种内群体感应的调控；2 通过河豚共栖非产毒菌Pseudomonas sp. TL-2 代谢产物中可能种间信号分子的分离鉴定 和种间信号分子对B. vallismortis TL-1 代谢产河豚毒素的调控研究来论证Pseudomonas sp.TL-2 是否对B. vallismortis TL-1代谢产河豚毒素行为产生种间群体感应调控。项目工作结果表明，B. vallismortis TL-1 代谢产河豚毒素行为受到种内群体感应的调控的假说没有充分证据证实，也不能确定存在种类信号分子；Pseudomonas sp.TL-2 并不对B. vallismortis TL-1代谢产河豚毒素行为产生种间群体感应调控，也不存在相应的种间信号分子。因此，项目得出结论：两个假说（B. vallismortis TL-1 代谢产河豚毒素行为受到种内/种间群体感应的调控）并不成立。该结果为其他把研究方向定位为群体感应调控河豚毒素代谢的研究者提供了思考和借鉴。