Electron acceptor redox potential globally regulates transcriptomic profiling in Shewanella decolorationis S12.

Yingli Lian,Xiaojing Li,Yun Fang,Meiying Xu,Yan Wang,Jun Guo,Yonggang Yang,Lixia Gan

doi:10.1038/srep31143

Abstract

Electron acceptor redox potential (EARP) was presumed to be a determining factor for microbial metabolism in many natural and engineered processes. However, little is known about the potentially global effects of EARP on bacteria. In this study, we compared the physiological and transcriptomic properties of Shewanella decolorationis S12 respiring with different EARPs in microbial electrochemical systems to avoid the effects caused by the other physicochemical properties of real electron acceptor. Results showed that the metabolic activities of strain S12 were nonlinear responses to EARP. The tricarboxylic acid cycle for central carbon metabolism was down-regulated while glyoxylate shunt was up-regulated at 0.8 V compared to 0.2 and −0.2 V, which suggested that EARP is an important but not the only determinant for metabolic pathways of strain S12. Moreover, few cytochrome c genes were differentially expressed at different EARPs. The energy intensive flagella assembly and assimilatory sulfur metabolism pathways were significantly enriched at 0.8 V, which suggested strain S12 had stronger electrokinesis behavior and oxidative stress-response at high EARP. This study provides the first global information of EARP regulations on microbial metabolism, which will be helpful for understanding microorganism respiration.

Highlights

Electron acceptor redox potential (EARP) was presumed to be a determining factor for microbial metabolism in many natural and engineered processes
Confocal laser scanning microscopy (CLSM) results showed that only scarce cell clusters were observed on the anode surfaces in all Microbial electrochemical systems (MES) which can be attributed to the short cultivation time (8 h, Supplementary Fig. S1)
A significant partial of genes involved in central carbon metabolism, sulfur metabolism, cell motility and stress-response showed specific responses to EARP by analyzing the global transcriptomic profiling of S. decolorationis S12

Summary

Introduction

Electron acceptor redox potential (EARP) was presumed to be a determining factor for microbial metabolism in many natural and engineered processes. Microbial respiration with electrode is a central driving force for the complex bioelectrochemical functions in MES, while only few studies paid attention on the regulation of EARP on the intracellular processes, or only focused on several EARP-specific enzymes involved in TCA cycle and the electron transfer process[10,12]. Based on previous reports[6,7,10,12], we hypothesized that, in addition to genes encoding the components in TCA cycle and electron transfer chain, some important but ignored energy intensive metabolic pathways may be enriched at more positive potentials which may be responsible for the nonlinear responses. In order to verify our hypothesis, global and comprehensive information of EARP regulation on microorganism metabolism is essential

Methods

Results

Conclusion