Sensitivity to Oxygen in Microbial Electrochemical Systems Biofilms

Abstract

Summary The formation and bioelectric performance of anode biofilms in microbial electrochemical systems (MESs) are sensitive to oxygen. Investigating the temporal-spatial structure of anode biofilms will help elucidate the interfaces between oxygen and bacteria, thereby facilitating the applications of MESs in wastewater treatment and energy recovery. Here, use of optical coherence tomography, frozen sections, and a microsensor revealed that the aerobic biofilms exhibited a multilayered sandwich structure with a sparse gap between the aerobe- and amphimicrobe-enriched outer layer and the dense exoelectrogen-enriched inner layer, whereas the anaerobic biofilm consisted of only a single dense layer. Our results showed that the inner layer of aerobic anode biofilms performed electricity generation, whereas the outer layer only consumed oxygen. In this case, electron donor diffusion through the outer layer became the limiting factor in electricity generation by the bioanode. Consequently, as the anode biofilms matured, current generation decreased.

A Biobattery Capsule for Ingestible Electronics in the Small Intestine: Biopower Production from Intestinal Fluids Activated Germination of Exoelectrogenic Bacterial Endospores

“…Usually, electricity-generating bacteria (i.e., exoelectrogens) tend to react with oxygen as a terminal electron acceptor and divert the metabolically produced electrons away from the MFC. [33,34] However, the development of an ingestible MFC for use in the small intestine must consider many critical requirements; i) selection of the bacterial type, ii) stringent size reduction for standard capsules, iii) high-performance generation sufficient for operating the potential multi-tasks, iv) reliable cathodic operation in the oxygen-deficit environment of the small intestine and v) selective operation only in the small intestine. First, it is challenging in making the pre-loaded bacterial cells viable until used to allow the MFC to have a long shelf-life without performance degradation.…”

In vivocharacterization of electroactive biofilms inside porous electrodes with MR Imaging

“…2,13,23,24,75 For instance, if fresh medium with dissolved oxygen is present at the liquid facing side, in the anaerobic depth of the biolm the terminal electron acceptor (TEA) is the electrode where the aerobic toplayer uses dissolved oxygen as TEA. 76 Moreover, the directional motility of cells may prevent penetrating deeper due to the higher redox potential of oxygen compared to the potential of the anode. 77 However, the observed optical density OD 600 < 0.1 in the growth medium does not indicate a high amount of dissolved oxygen (Fig.…”

New fragmented electro-active biofilm (FAB) reactor to increase anode surface area and performance of microbial fuel cell

“…The anode biofilm forms two layers; the inner layer generates electricity, whereas the outer layer consumes oxygen. Thick anode biofilms are essential because they minimize oxygen sensitivity (Yang et al 2019). On the contrary, in pure Geobacter sulfurreducens, thin biofilm thickness (~ 20 μm) results in the highest power output, but the performance decline as thickness increases due to the dead biomass accumulates in the inner side of the electrode and develop resistance (Sun et al 2016).…”