Paper

Negative interplay between biofilm formation and competence in the environmental strains of Bacillus subtilis

Hunter, Evan, Nicolau, Samantha, Wang, Hongkai, Qin, Yuxuan, Chen, Yun, Zalis, Eliza A, She, Qianxuan, Chai, Yunrong

2020

Overview

Environmental strains of the soil bacterium Bacillus subtilis have valuable applications in agriculture, industry, and biotechnology. They are capable of forming robust biofilms and demonstrate excellent biological control activities in plant protection. However, environmental strains are genetically less accessible, a sharp contrast to the laboratory strains well known for their natural competence and a limitation toward their application. In this study, we observed that robust biofilm formation of the environmental strains greatly reduces the rate of competent cells within the biofilm. By using the model strain 3610, we reveal a cross-pathway regulation that allows biofilm matrix producers and competence-developing cells to undergo mutually exclusive cell differentiation. We show that the competence activator ComK represses the key biofilm regulatory gene sinI by directly binding to the sinI promoter, thus blocking competent cells from simultaneously becoming matrix producers. In parallel, the biofilm activator SlrR represses competence through three distinct mechanisms, involving both genetic regulation and cell morphological changes. We discuss potential implications of limiting competence in a bacterial biofilm.

• Publisher: Cold Spring Harbor Laboratory Press,Cold Spring Harbor Laboratory
• Subject: Bacillus subtilis / Biofilms / Biological control / Biotechnology / Cell differentiation / Microbiology / Plant protection / Soil microorganisms / Strains (organisms)