Quorum-Sensing Signals from Epibiont Mediate the Induction of Novel Microviridins in the Mat-Forming Cyanobacterial Genus Nostoc

The regulation of bioactive peptides production in cyanobacteria is an important phenomenon to understand the ecological prospective of cyanobacterial bloom occurrence. The role of chemical communication between the cyanobacterium and the microbial community harboured as epibionts within its exopolysaccharide sheath is at initial stage of research and very little is known about its specificity. In the current study, we tried to establish the role of epibionts in regulation of the production of bioactive tricyclic oligopeptide microviridin (MDN) in a soil cyanobacterium, Nostoc sp. strain 122. Three novel MDN (Microviridin-1688, Microviridin-1739 and Microviridin-1748) were purified and their structures were elucidated by coupling genomic data and the product ion spectra.

蓝细菌（cyanobacteria）生物活性肽（bioactive peptides）的合成调控机制，是解析蓝藻水华（cyanobacterial bloom）发生生态学机制的重要研究内容。蓝细菌与其胞外多糖鞘（exopolysaccharide sheath）内附生的微生物群落之间的化学通讯（chemical communication）作用，目前仍处于研究初期，其特异性机制尚鲜有探明。本研究以一株土壤蓝细菌念珠藻属（Nostoc sp.）菌株122为研究对象，旨在明确附生生物（epibionts）在其生物活性三环寡肽（tricyclic oligopeptide）微病毒素（microviridin, MDN）合成调控中的作用。本研究纯化得到三种新型MDN：Microviridin-1688、Microviridin-1739及Microviridin-1748，并通过整合基因组数据与产物离子谱（product ion spectra）解析了其化学结构。