A mechanistic understanding of Desulfovibrio vulgaris Hildenborough biofilm formation and the genetic requirements for survival in coculture with Clostridium acetobutylicum

Abstract

Sulfate-reducing bacteria impact the world through the biofilms they form in environmental and industrial systems, and through the interspecies connections made with other bacteria. The biofilms formed by sulfate-reducing bacteria cost the United States alone hundreds of millions of dollars annually due to microbiologically influenced corrosion and the biofouling of petroleum fuels. The biofilms formed by sulfate-reducing bacteria and association-dependent interactions with other bacteria have also been used in the generation of clean energy, using biological batteries and the generation of hydrogen, respectively. The consequences of sulfate-reducing bacterial biofilms and interspecies associations have been previously characterized; however, the mechanisms and genetic requirements for biofilm formation and for direct intercellular connections have not been determined. Here, this work describes the role of two surface proteins from Desulfovibrio vulgaris Hildenborough in biofilm formation and surface attachment, and the genetic requirements that allow for the survival of this bacterium in cocultures with the solventogen Clostridium acetobutylicum ATCC 824. Through proteomic analyses and microscopy, this work identified the proteomic changes to biofilm composition in protein deletion mutants, and the roles of the adhesins in surface attachment and cell aggregation. Coculture studies with gene deletion mutants and transcriptomic analyses identified the importance of flagella and tryptophan biosynthesis in the survival of D. vulgaris in cocultures with C. acetobutylicum. This work furthers the understanding of biofilm adhesins of D. vulgaris, the potential function of homologous proteins in other species, and the genetic requirements for coculture survivability in obligate commensal conditions.