Mg2+/Ca2+ promotes the adhesion of marine bacteria and algae and enhances following biofilm formation in artificial seawater

Adhesion of microorganisms in the marine environment is essential for initiation and following development of biofouling. A variety of factors play roles in regulating the adhesion. Here we report the influence of Ca2+ and Mg2+ in artificial seawater on attachment and colonization of Bacillus sp., Chlorella and Phaeodactylum tricornutum on silicon wafer. Extra addition of the typical divalent cations in culturing solution gives rise to significantly enhanced adhesion of the microorganisms. Mg2+ and Ca2+ affect the adhesion of Bacillus sp. presumably by regulating aggregation and formation of extracellular polymeric substances (EPS). The ions alter quantity and types of the proteins in EPS, in turn affecting subsequent adhesion. However, it is noted that Mg2+ promotes adhesion of Chlorella likely by regulating EPS formation and polysaccharide synthesis. Ca2+ plays an important role in protein expression to enhance the adhesion of Chlorella. For Phaeodactylum tricornutum, Ca2+ expedites protein synthesis for enhanced adhesion. The results shed some light on effective ways of utilizing divalent cations to mediate formation of biofilms on the marine structures for desired performances. (C) 2016 Elsevier B.V. All rights reserved.