Bioelectrochemical systems: Exploring microbial communities, interactions, and electron transfer

Bioelectrochemical system (BES) relies on the electrochemical reactions derived from the interaction between microorganisms and solid electrodes to enable processes such as electricity generation and other biotechnological applications. The diversity of these electroactive microorganisms capable of extracellular electron transfer (EET) spread across all three domains of life. The expanding research in this domain focuses on enhancing the EET capabilities of these exoelectrogens and exploring non-exoelectrogens that can support them while reducing waste through various biogeochemical processes. Approaches such as biofilm improvement, genetic modification of electron-conducting proteins, and overexpressing redox mediators are explored to increase EET efficiency. Electrochemically inactive fermentative microorganisms that are non-exoelectrogens often coexist with exoelectrogens. Although their presence has been associated with increased power generation, their excessive proliferation can diminish power output. Therefore, understanding the synergies and intricate balance between exoelectrogens and non-exoelectrogens is necessary. This review discusses the mechanism of EET, strategies to improve EET by engineering microbial communities, the role of non-exoelectrogens involved in the BES, interactions, and synergies within microbial consortia and the factors that affect them, as well as their community structure and dynamics. This review seeks to elucidate the complex interplay within BES and pave the way for future advancements in this field by examining these aspects.