Enhanced Shewanella biofilm promotes bioelectricity generation

Electroactive biofilms play essential roles in determining the power output of microbial fuel cells (MFCs). To engineer the electroacitve biofilm formation of Shewanella oneidensis MR-1, a model exoelectrogen, we herein heterologously overexpressed a c-di-GMP biosynthesis gene ydeH in S. oneidensis MR-1, constructing a mutant strain in which the expression of ydeH is under the control of IPTG-inducible promoter, and a strain in which ydeH is under the control of a constitutive promoter. Such engineered Shewanella strains had significantly enhanced biofilm formation and bioelectricity generation. The MFCs inoculated with these engineered strains accomplished a maximum power density of 167.6 +/- 3.6mW/m(2), which was approximate to 2.8 times of that achieved by the wild-type MR-1 (61.0 +/- 1.9mW/m(2)). In addition, the engineered strains in the bioelectrochemical system at poised potential of 0.2V vs. saturated calomel electrode (SCE) generated a stable current density of 1100mA/m(2), approximate to 3.4 times of that by wild-type MR-1 (320mA/m(2)). Biotechnol. Bioeng. 2015;112: 2051-2059. (c) 2015 Wiley Periodicals, Inc.