Enhancing biofilm formation by feedback deregulation of GGDEF domain protein AdrA allows improved glucose conversion in immobilized cell reactors.

摘要

Bacterial cells are able to switch between two forms of life, planktonic and sessile in response to chemical fluctuations in their local environment. Changes in cell phenotype occur as a result of DGC mediated regulation in the levels of the intracellular secondary metabolite, cyclic di-GMP. Cells that have high levels of cyclic di-GMP are triggered into the biofilm lifestyle, can achieve high cell densities and are highly resistant to antimicrobial agents in their environment, making them potentially good biocatalysts in the conversion of biomass feedstocks. In this study, the DGC gene AdrA is mutated at the RXXD feedback regultion site for cyclic di GMP production, with the aims of enhancing the biofilm phenotype. The resulting mutants were assayed for changes in phenotype on CR and motility plates. E. coli Mach 1 pSMART-adrA-R208G and E. coli Mach 1 pSMART-adrA-D283A showed enhanced attachment to a sand-column assay indicating enhanced biofilm phenotype in the absence of an environmental trigger. E. coli Mach 1 pSMART-adrA-R208G also showed improved succinate productivity of 0.046 g/L/hr over the Mach 1 pSMART empty vector (0.034 g/L/hr) when immobilized on the surface of diatomaceous earth pellets.