Lack of Periplasmic Non-heme Protein SorA Increases Shewanella decolorationis Current Generation

Guannan Kong; Da Song; Jun Guo; Guoping Sun; Chunjie Zhu; Fusheng Chen; Yonggang Yang; Meiying Xu

doi:10.3389/fmicb.2020.00262

Lack of Periplasmic Non-heme Protein SorA Increases Shewanella decolorationis Current Generation

Front Microbiol. 2020 Feb 25:11:262. doi: 10.3389/fmicb.2020.00262. eCollection 2020.

Authors

Guannan Kong^{1

2

3}, Da Song^{2

3}, Jun Guo^{2

3}, Guoping Sun², Chunjie Zhu², Fusheng Chen⁴, Yonggang Yang^{2

3

5}, Meiying Xu^{2

3}

Affiliations

¹ School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China.
² Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, China.
³ State Key Laboratory of Applied Microbiology Southern China, Guangzhou, China.
⁴ College of Food Science and Technology, Henan University of Technology, Zhengzhou, China.
⁵ Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangzhou, China.

Abstract

Bacterial extracellular electron transport (EET) plays an important role in many natural and engineering processes. Some periplasmic non-heme redox proteins usually coexist with c-type cytochromes (CTCs) during the EET process. However, in contrast to CTCs, little is known about the roles of these non-heme redox proteins in EET. In this study, the transcriptome of Shewanella decolorationis S12 showed that the gene encoding a periplasmic sulfite dehydrogenase molybdenum-binding subunit SorA was significantly up-regulated during electrode respiration in microbial fuel cells (MFCs) compared with that during azo-dye reduction. The maximum current density of MFCs catalyzed by a mutant strain lacking SorA (ΔsorA) was 25% higher than that of wild strain S12 (20 vs. 16 μA/cm²). Both biofilm formation and the current generation of the anodic biofilms were increased by the disruption of sorA, which suggests that the existence of SorA in S. decolorationis S12 inhibits electrode respiration. In contrast, disruption of sorA had no effect on respiration by S. decolorationis S12 with oxygen, fumarate, azo dye, or ferric citrate as electron acceptors. This is the first report of the specific effect of a periplasmic non-heme redox protein on EET to electrode and provides novel information for enhancing bacterial current generation.

Keywords: SorA; biofilm; current generation; extracellular electron transport; molybdenum-binding protein.