Potassium channel mediates electroactive biofilm formation via recruiting planktonic Geobacter cells.

Potassium (K)-channel-based electrical signaling can coordinate microbial actions at a distance that provides an evolutionary advantage to cell communities. Electroactive cells are usually cultured surrounded by an electric field which provided stronger electrical signaling than the K-mediated electrical signaling. Whether the K signaling also plays a role in coordinating the behavior of electroactive microorganisms has not been accurately demonstrated.

Anode respiration-dependent biological nitrogen fixation by Geobacter sulfurreducens.

The present nitrogen fixation industry is usually energy-intensive and environmentally detrimental. Therefore, it is appealing to find alternatives. Here, we achieved both a synchronized biological nitrogen fixation and electric energy production by using Geobacter sulfurreducens in a microbial electrochemical system.

Enhanced aging of polystyrene microplastics in sediments under alternating anoxic-oxic conditions.

Aging of microplastics (MPs) (i.e., degradation and weathering) is ubiquitous in the environment.

Bioelectrochemical Fixation of Nitrogen to Extracellular Ammonium by Pseudomonas stutzeri.

Diazotrophs can produce bioavailable nitrogen from inert N gas by bioelectrochemical nitrogen fixation (-BNF), which is emerging as an energy-saving and highly selective strategy for agriculture and industry. However, current -BNF technology is impeded by requirements for NH assimilation inhibitors to facilitate intracellular ammonia secretion and precious metal catalysts to generate H as the energy-carrying intermediate. Here, we initially demonstrate inhibitor- and catalystless extracellular NH production by the diazotroph Pseudomonas stutzeri A1501 using an electrode as the sole electron donor.

Potassium channel blocker inhibits the formation and electroactivity of Geobacter biofilm.

Bacteria in biofilms are able to utilize potassium ion channel-mediated electrical signaling to achieve cell-cell communication. However, it remains unclear whether these signals play a role in Geobacter sp. when surrounded by an intense electric field.

Flagella act as Geobacter biofilm scaffolds to stabilize biofilm and facilitate extracellular electron transfer.

Flagella are widely expressed in electroactive biofilms; however, their actual role is unknown. To understand the role of flagella, two Geobacter sulfurreducens strains (KN400 and PCA, with and without flagella, respectively) were selected. We restored flagellum expression in trans in strain PCA and prevented flagellum expression in strain KN400.

A pilin chaperone required for the expression of electrically conductive Geobacter sulfurreducens pili.

Mechanisms controlling the expression of the electrically conductive pili (e-pili) of Geobacter species are of interest because of the important role of e-pili in diverse biogeochemical processes, anaerobic digestion and electromicrobiological applications. We investigated the function of the protein, designated Spc (short pilin chaperone), encoded by the gene immediately downstream from the gene for PilA, the monomer that assembles into e-pili. Multiple lines of evidence suggest that Spc forms an oligomer that is associated with the inner membrane.

Chemical signals stimulate Geobacter soli biofilm formation and electroactivity.

Biofilm formation and maturation have been demonstrated to be regulated by distinct forms of cell-cell communication factors such as chemical and physical signals. However, whether the Geobacter sp. biofilms, which are typical electroactive biofilms, are affected by chemical signals is poorly understood.

Enhanced electrosynthesis performance of Moorella thermoautotrophica by improving cell permeability.

Microbial electrosynthesis systems (MES) are promising devices in which microbes obtain electrons from electrodes to produce extracellular multicarbon compounds. This study investigates whether improvement in cell permeability can enhance electrosynthesis performance of Gram-positive Moorella thermoautotrophica in MES. Results showed that when ≤30mg/L penicillin was added, the cell permeability was doubled, and the electron uptake per biomass (including both cathode-associated biomass and suspended biomass) was 1.

Quorum sensing signals enhance the electrochemical activity and energy recovery of mixed-culture electroactive biofilms.

The impacts of exogenous or endogenous quorum sensing (QS) signaling molecules on mixed-culture electroactive biofilms (EABs), especially extracellular polymeric substances (EPS) and exoelectrogens using direct electron transfer mechanism inside EABs are poorly understood. This research focuses on the influence of acylhomoserine lactones (AHLs), the most common QS signaling molecules for gram negative bacteria, on mixed-culture EABs. Results indicated that both exogenous and endogenous AHLs played the role as regulators to improve the electrochemical activities of EABs.