Extracellular Electron Transfer Between Birnessite and Electrochemically Active Bacteria Community from Red Soil in Hainan, China

Abstract

The interplay between electrochemically active microorganisms (EAMs) and adjacent minerals universally occurs in natural environments, in which soil is an extremely typical and active one. We stimulated the extracellular electron transfer (EET) process between the bacterial community and birnessite in red soil (collected from Hainan, China) by constructing a microbial fuel cell equipped with synthetic birnessite cathode. Compared to graphite-cathode, the cell voltage of birnessite-cathode was increased by 22% when loading a 1000 Ω-resistance, indicating the EET between microbes and birnessite. Eleven genera of EAMs in red soil were confirmed through 16S rRNA analysis. Neither palpable novel mineral formation nor change of birnessite crystallinity was observed after reaction by Raman and SEM. As oxygen pumped into cathode chamber was the terminal electron acceptor, birnessite principally performed as an intermediate of holistic electron transfer process to favor the cathodic oxygen reduction.

Keywords:

• Extracellular electron transfer
• birnessite
• electrochemically active microorganisms
• red soil

Acknowledgment

We thank Yueliang Gu and Xiaolong Li for their experimental guidance in synchrotron radiation XRD measurement in Shanghai Synchrotron Radiation Facility and Yifeng Jiang for her technical assistance in SEM sample preparation and image analysis at the Core Facilities of College of Life Science, Peking University

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was funded by the National Basic Research Program of China, Grant No. 2014CB846001, Natural Science of Foundation of China, Grant No. 41230103, 41522201, 41402032, NSFC Projects of International Cooperation and Exchanges, Grant No. 418001018.