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.