Bacterial cellulose synthesis gene regulates cellular c-di-GMP that control Biofilm formation and mussel larval settlement

Abstract Bacterial cellulose is a widely dispersed biofilm matrix component, yet the role of cellulose synthesis-encoding gene on the settlement of macrofouling organisms remains elusive. Here, the functional role of the cellulose synthesis gene bcsQ of the bacterium Pseudoalteromonas marina on settlement of Mytilus coruscus larvae was investigated. It was found that the deficiency of the gene bcsQ was associated with biofilm-settlement inducing activity, the secretion of bacterial α- and β-polysaccharides, and cytosolic c-di-GMP content change. The deletion of the gene bcsQ downregulated c-di-GMP level accompanied by reduced production of polysaccharides including cellulose and colanic acid. Bacterial characteristics in the deficient knockout of bcsQ also changed showing a slow cell growth, reducing biofilm forming capacity and increasing biofilm dispersion. The larval settlement rate of M. coruscus onto the ΔbcsQ biofilm was about 46% lower than that of the wild-type strain in comparison. Therefore, the gene bcsQ manipulates cytosolic c-di-GMP that controls secretion of exopolysaccharides and biofilm formation, and indirectly regulates mussel settlement. The present findings shed new light on interactions among function of bacterial cellulose biosynthesis gene, biofilm formation and the settlement of typical fouling organisms.