Extracellular electron transfer via multiple electron shuttles in waterborneAeromonas hydrophilafor bioreduction of pollutants

Abstract

Members of the genus Aeromonas prevail in aquatic habitats and have a great potential in biological wastewater treatment because of their unique extracellular electron transfer (EET) capabilities. However, the mediated EET mechanisms of Aeromonas have not been fully understood yet, hindering their applications in biological wastewater treatment processes. In this study, the electron shuttles in Aeromonas hydrophila, a model and widespread strain in aquatic environments and wastewater treatment plants, were explored. A. hydrophila was found to produce both flavins and 2-amino-3-carboxy-1,4-naphthoquinone (ACNQ) as electron shuttles and utilize them to accelerate its EET for the bioreduction of various pollutants.The Mtr-like respiratory pathway was essential for the reduction of flavins, but not involved in the ACNQ reduction. The electron shuttle activity of ACNQ for pollutant bioreduction involved the redox reactions that occurred inside the cell. These findings deepen our understanding about the underlying EET mechanisms in dissimilatory metal reducing bacteria and provide new insights into the roles of the genus Aeromonas in biological wastewater treatment.

Engineering extracellular electron transfer pathways of electroactive microorganisms by synthetic biology for energy and chemicals production

“…251 Recently, Min et al found that Aeromonas hydrophila , a novel electroactive strain, can produce ACNQ as an electron shuttle to be used in EET. 252 When menC is mutated, the reduction capacity of amaranth was inhibited, but it can be recovered upon adding 200 nm ACNQ. The results indicated that ACNQ was mainly involved in the intracellular redox reaction, which was different from the flavin-mediated EET mechanism.…”

Evaluating effectiveness of electron shuttles in environments with a WO3 nanoprobe

“…The WO 3 nanoprobe has been used to show the presence of ESs in our previous studies. [41][42][43] However, the plate-based procedure still requires complex operation and data analysis. In this work, the colour change of the fabricated WO 3 test paper could directly indicate the presence of ES species.…”