Biological modification in air-cathode microbial fuel cell: Effect on oxygen diffusion, current generation and wastewater degradation

Oxygen diffusion in the anodic chamber is the major limitation of air-cathode microbial fuel cell (MFC) design. To address this drawback, the application of microbial (Escherichia coli EC) patch on cathode was tested. Pseudomonas aeruginosa BR was used as exoelectrogen during the study. The MFC reactor with a patch had a better electron transfer rate, degraded 94.64% of synthetic wastewater (BR_SyW) and its current generation was increased by 95.66%. The maximum power density recorded for BR_SyW was 259.34 ± 7.28 mW/m². Application of patch in real wastewater (BR + Sludge) condition registered 63.18% of wastewater degradation, increment in current generation (59.71%) and decreased the charge transfer and ohmic resistances by 97.95% and 97.01% respectively. Apart from hindering oxygen diffusion and better current generation, this simple design also worked as a two-step degradation system. Thus, such MFC reactor is a potential candidate for wastewater management and green energy generation.

Internal Redox Polarity of an Individual G. sulfurreducens Bacterial Cell Attached to an Inorganic Substrate

Bacterial cell polarity is an internal asymmetric distribution of subcellular components, including proteins, lipids, and other molecules that correlates with the cell ability to sense energy and metabolite sources, chemical signals, quorum signals, toxins, and movement in the desired directions. This ability also plays central role in cell attachment to various surfaces and biofilm formation. Mechanisms and factors controlling formation of this cell internal asymmetry are not completely understood. As a step in this direction, in the present work, we develop an approach for analyzing how information about inorganic substrate can be non-genetically coded inside an individual bacterial cell. As a model system, we use G. sulfurreducens cells attached to an inorganic mineral, mica. The approach utilizes confocal Raman microscopy, Gaussian deconvolution, and Principal Component Analysis (PCA) and allows for quick label-free identification of the molecular signature of cytochrome intracellular location and the cell to substrate binding down to the level of individual bacterial cells. Our results describe a spectroscopic signature of cell adhesion and how the information about cell adhesion can be coded inside individual bacterial cells.