Exploring the Effects of bolA in Biofilm Formation and Current Generation by Shewanella oneidensis MR-1.

Miriam Edel,Johannes Gescher,Catarina M. Paquete,Ana V. Silva

doi:10.3389/fmicb.2020.00815

Abstract

Microbial electrochemical technologies (METs) have emerged in recent years as a promising alternative green source of energy, with microbes consuming organic matter to produce energy or valuable byproducts. It is the ability of performing extracellular electron transfer that allows these microbes to exchange electrons with an electrode in these systems. The low levels of current achieved have been the limiting factor for the large-scale application of METs. Shewanella oneidensis MR-1 is one of the most studied electroactive organisms regarding extracellular electron transfer, and it has been shown that biofilm formation is a key factor for current generation. The transcription factor bolA has been identified as a central player in biofilm formation in other organisms, with its overexpression leading to increased biofilm. In this work we explore the effect of this gene in biofilm formation and current production by S. oneidensis MR-1. Our results demonstrate that an increased biofilm formation and consequent current generation was achieved by the overexpression of this gene. This information is crucial to optimize electroactive organisms toward their practical application in METs.

Highlights

Microorganisms have developed strategies to live in virtually every environment on Earth, being able to scavenge energy from a wide range of organic and inorganic compounds
We demonstrate that the bolA gene increases both current generation in bioelectrochemical systems (BES) and biofilm formation, opening the way for future regulation studies focusing on this gene
The bolA gene was originally identified as a transcriptional regulator for cell shape in E. coli, as its overexpression leads to round cell morphology (Aldea et al, 1988)

Summary

Introduction

Microorganisms have developed strategies to live in virtually every environment on Earth, being able to scavenge energy from a wide range of organic and inorganic compounds. BES arose as a sustainable platform for electricity production (Logan et al, 2006), nowadays they can be used for wastewater treatment, environmental bioremediation, biofuel production, bioelectrosynthesis and biosensing (Logan and Regan, 2006; Arends and Verstraete, 2012; Ucar et al, 2017; Logan et al, 2019; Mohan et al, 2019; Simonte et al, 2019) Their large-scale application has been set back by the low power densities obtained so far, mainly limited by the slow electron transfer rates between electroactive organisms and electrodes. Numerous efforts have been made in recent years to optimize power generation in BES, including the characterization and optimization of electroactive organisms, in particular of the model organisms Shewanella oneidensis MR-1 and Geobacter sulfurreducens (Teravest et al, 2015; Yang et al, 2015; Bursa et al, 2017; Min et al, 2017; Ueki et al, 2018; Delgado et al, 2019; Fonseca et al, 2019; Reguera and Kashefi, 2019)

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Results

Conclusion