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Updated: Aug 11, 2026

Electrochemical Detection of Deuterium Kinetic Isotope Effect on Extracellular Electron Transport in Shewanella oneidensis MR-1
Published on: April 16, 2018
Nitrate and iron salts enhanced Shewanella MR-1 bioreduction on Cr(VI) by stimulating cytochrome c electron
Chuanlong Huang1, Mengqi Hao1, Shurun Yao1
1Yunnan Key Laboratory of Soil Carbon Sequestration and Pollution Control, Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China.
Abstract:
Bioreduction of Cr(VI) by Shewanella through extracellular electron transmission (EET) attracts increasing interest due to cytochrome c (cyts c) system especially conductive flagella ("nanowire") structure. The responses of bioreduction efficiency, "nanowire" growth, cyts c synthesis, and e (electron) transmission intensity through CymA→MtrA→MtrB→MtrC→OmcA (Route 1) and CymA→NapA→NapB (Route 2) to iron ion (Fe3 +) and nitrate (NO3-) were evaluated. Results showed that Fe3+ and NO3- of 1-1.5 mM significantly (p < 0.01) enhanced bioreduction of Cr(VI) from 67% to 82% and 79%, respectively with promoted cyts c-mediated conductivity (Cp). Both Fe3+ and NO3- stimulated the growth of "nanowire" and synthesis of cyts c participating in EET with Fe3+ showing stronger stimulation on Routes 1 while NO3- on Routes 2. The genes expression of cyts c on inner membrane (CymA), periplasmic space (NapA/NapB), and "nanowire" (MtrA/MtrB/MtrC, OmcA) show synchronous responses to Fe3+ and NO3-. However, contents of mobile cyts c in extracellular polymeric substances (EPS) and structural cyts c in cell membrane showed inconsistent responses to Fe3+ and NO3-. Overall, this study illustrated the regulation mechanism of e acceptors on cyts c- electron transmission system of Shewanella, which help improving the electrochemical efficiency on Shewanella and provide novel idea in chromium remediation strategy.
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