Overexpression of the endogenous diguanylate cyclase gene dgcS enhances biofilm formation by Shewanella oneidensis MR-1 on electrodes
- 1School of Life Sciences, Tokyo University of Pharmacy and Life Sciences
- 2Faculty of Life Sciences, Toyo University
Abstract
In microbial electrochemical technologies, Shewanella oneidensis MR-1 efficiently generates electric current via biofilm formation on electrodes. A previous study demonstrated that the deletion of the diguanylate cyclase gene dgcS inhibits biofilm formation on electrodes and current generation in MR-1. However, the molecular mechanisms by which dgcS expression and subsequent cyclic dimeric guanosine monophosphate (c-di-GMP) signaling affect these processes remain unexplored. Here, we investigated the effects of dgcS overexpression on current generation, electrode-associated biofilm formation, and the intracellular concentration of cyclic AMP (cAMP), a second messenger that induces the expression of extracellular electron transfer (EET)-related genes in MR-1, to examine the potential coordinated regulation of intracellular c-di-GMP and cAMP levels. In an electrochemical flow cell (EFC), the dgcS -overexpressing ( dgcS -OE) strain exhibited significantly higher intracellular c-di-GMP concentrations than the vector control (VC) strain, forming more biomass-rich biofilms on the electrode and generating higher current. However, current generation normalized to electrode-associated biomass did not differ significantly between the dgcS -OE and VC strains, suggesting that dgcS overexpression did not increase EET activity per biomass. Moreover, intracellular cAMP levels were not significantly different between the dgcS -OE and VC strains, and the transcription levels of adenylate cyclase (cAMP synthase) genes and EET-related genes in the dgcS -OE strain tended to be reduced to 0.3- to 0.6-fold of those in the VC strain. Collectively, these findings suggest that dgcS overexpression and the associated elevation of intracellular c-di-GMP levels enhance the electrogenic performance of MR-1 primarily by promoting biofilm development on electrodes, while weakly repressing the transcription of genes related to cAMP signaling.
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BibTeX
@article{iwanami2026overexpression,
title = {{Overexpression of the endogenous diguanylate cyclase gene dgcS enhances biofilm formation by Shewanella oneidensis MR-1 on electrodes}},
author = {Nanae Iwanami and Akiho Matsumoto and Ryotaro Yamamoto and Keisuke Tomita and Atsushi Kouzuma and Kazuya Watanabe},
journal = {Frontiers in Microbiology},
year = {2026},
month = oct,
doi = {10.3389/fmicb.2026.1957821},
url = {https://www.frontiersin.org/articles/10.3389/fmicb.2026.1957821/full},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Overexpression of the endogenous diguanylate cyclase gene dgcS enhances biofilm formation by Shewanella oneidensis MR-1 on electrodes
AU - Nanae Iwanami
AU - Akiho Matsumoto
AU - Ryotaro Yamamoto
AU - Keisuke Tomita
AU - Atsushi Kouzuma
AU - Kazuya Watanabe
PY - 2026
DA - 2026/10/14
JO - Frontiers in Microbiology
DO - 10.3389/fmicb.2026.1957821
UR - https://www.frontiersin.org/articles/10.3389/fmicb.2026.1957821/full
AB - In microbial electrochemical technologies, Shewanella oneidensis MR-1 efficiently generates electric current via biofilm formation on electrodes. A previous study demonstrated that the deletion of the diguanylate cyclase gene dgcS inhibits biofilm formation on electrodes and current generation in MR-1. However, the molecular mechanisms by which dgcS expression and subsequent cyclic dimeric guanosine monophosphate (c-di-GMP) signaling affect these processes remain unexplored. Here, we investigated the effects of dgcS overexpression on current generation, electrode-associated biofilm formation, and the intracellular concentration of cyclic AMP (cAMP), a second messenger that induces the expression of extracellular electron transfer (EET)-related genes in MR-1, to examine the potential coordinated regulation of intracellular c-di-GMP and cAMP levels. In an electrochemical flow cell (EFC), the dgcS -overexpressing ( dgcS -OE) strain exhibited significantly higher intracellular c-di-GMP concentrations than the vector control (VC) strain, forming more biomass-rich biofilms on the electrode and generating higher current. However, current generation normalized to electrode-associated biomass did not differ significantly between the dgcS -OE and VC strains, suggesting that dgcS overexpression did not increase EET activity per biomass. Moreover, intracellular cAMP levels were not significantly different between the dgcS -OE and VC strains, and the transcription levels of adenylate cyclase (cAMP synthase) genes and EET-related genes in the dgcS -OE strain tended to be reduced to 0.3- to 0.6-fold of those in the VC strain. Collectively, these findings suggest that dgcS overexpression and the associated elevation of intracellular c-di-GMP levels enhance the electrogenic performance of MR-1 primarily by promoting biofilm development on electrodes, while weakly repressing the transcription of genes related to cAMP signaling.
SN - 1664-302X
ER -