Bioelectronics brings together the fields of biology and microelectronics to create multifunctional devices with the potential to address longstanding technological challenges and change our way of life. Microbial electrochemical devices are a growing subset of bioelectronic devices that incorporate naturally occurring or synthetically engineered microbes into electronic devices and have broad applications including energy harvesting, chemical production, water remediation, and environmental and health monitoring. The goal of this Viewpoint is to highlight recent advances and ongoing challenges in the rapidly developing field of microbial bioelectronic devices, with an emphasis on materials challenges. We provide an overview of microbial bioelectronic devices, discuss the biotic−abiotic interface in these devices, and then present recent advances and ongoing challenges in materials related to electron transfer across the abiotic−biotic interface, microbial adhesion, redox signaling, electronic amplification, and device miniaturization. We conclude with a summary and perspective of the field of microbial bioelectronics.

The pathway from acetyl-CoA to butyryl-CoA serves as a major carbon metabolism channel in Clostridium acetobutylicum and other butyrate-forming clostridia, and the steps are similar to those involved in fatty acid metabolism. Recent findings are discussed, reviewing the isolation and characterization of the enzymes of the pathway, and the analyses of metabolic intermediate levels and possible points of regulation of enzyme activity by CoA compounds. DNA analyses have identified the genes for two thiolase proteins, and an apparent operon encoding five proteins involved in the conversion of acetoacetyl-CoA to butyryl-CoA. These five proteins are /3-hydroxybutyryl-CoA dehydrogenase, crotonase, butyryl-CoA dehydrogenase and the a and /3 subunits of an electron transfer flavoprotein.

Aims: To evaluate a traditional yoghurt used as folk medicine for its ability to kill Helicobacter pylori in vitro. Methods and Results: Micro-organisms from the yoghurt were identified and tested in different food substrates for their effects on H. pylori in a co-culture well system. Two yeasts and several strains of lactobacilli were isolated from the yoghurt, and both the yeast and the lactobacilli independently showed cidal activity against H. pylori. The microbes from the original yoghurt also retained their cidal effect when grown in corn meal and soy milk. Conclusions: The yeast and lactobacilli found in this yoghurt form a hardy symbiotic culture. The organisms secrete soluble factors capable of killing H. pylori, and these factors may include some organic by-products of fermentation. Significance and Impact of the Study: These yoghurt-derived food preparations could become simple and inexpensive therapies to suppress H. pylori infections in endemic countries.

Aims: The aim of the study is to investigate the effect of multiple mutations in redox or energy producing pathways of Escherichia coli on metabolic product distribution in anaerobic-rich media cultures. Methods and Results: Various combinations of NADH dehydrogenase (NDH)-deficient, alcohol dehydrogenase (ADH), and phosphotransacetylase and acetate kinase (PTA-ACK) mutants were constructed. Anaerobic LB-glucose cultures of the strains were grown and extracellular metabolites were analysed and compared with those of the parental strain, E. coli MG1655. The profile of metabolites was examined in log phase and 24-h cultures. The results show the effects of altering NADH utilization pathways on distribution of metabolic products. Such information improves our understanding of metabolic shifts and may find application in metabolic engineering of E. coli.

No abstract