A genetic engineering strategy to enhance outer membrane vesicle-mediated extracellular electron transfer of Geobacter sulfurreducens.

Bioelectrochemical systems (BESs) are unique devices that harness the metabolic activity of electroactive microorganisms (EAMs) to convert chemical energy stored in organic substrates into electrical energy. Enhancing electron transfer efficiency between EAMs and electrodes is the key to practical implementation of BESs. Considering the role of outer membrane vesicles (OMVs) in mediating electron transfer of EAMs, a genetic engineering strategy to achieve OMVs overproduction was explored to enhance electron transfer efficiency and the underlying mechanisms were investigated.

The survival strategy of direct interspecies electron transfer-capable coculture under electron donor-limited environments.

Direct interspecies electron transfer (DIET) has been considered as an effective mechanism for interspecies electron exchange in microbial syntrophy. Understanding DIET-capable syntrophic associations under energy-limited environments is important because these conditions more closely approximate those found in natural subsurface environments than in the batch cultures in the laboratory. This study, investigated the metabolic dynamics and electron transfer mechanisms in DIET-capable syntrophic coculture of Geobacter metallireducens and Geobacter sulfurreducens under electron donor-limited condition.

sp. nov., a novel species isolated from mangrove sediment.

Three bacterial strains, designated as AS18, AS27 and AS39, were obtained from mangrove sediment sampled in Futian district, Shenzhen, PR China. Cells of these strains were Gram-negative rods with no flagella. They were able to grow at 10-42 °C (optimum, 37 °C), at pH 5-9 (optimum, pH 6) and in 1-11 % (w/v) NaCl (optimum, 2 %).

-associated prophages confer beneficial effect on dissimilatory reduction of Fe(III) oxides.

The dissimilatory reduction of Fe(III) oxides driven by Fe(III)-reducing bacteria (FRB) is an important biogeochemical process that influences not only iron cycling but also the biogeochemical cycles of carbon, trace metals, nutrients and contaminants. Phages have central roles in modulating the population and activity of FRB, but the mechanism for phage-involved Fe(III) oxide reduction is still unclear. This work used a common FRB, to explore the roles and underlying mechanisms of FRB-harboring prophages in the dissimilatory reduction of Fe(III) oxides.