Shewanellaceae

Shewanellaceae is a bacterial family within the order Shewanellales, class Deltaproteobacteria, and phylum Proteobacteria. Members are Gram-negative, mesophilic rods that exhibit diverse morphology depending on growth conditions. The family is distinguished by its facultatively anaerobic lifestyle and ability to use a wide range of electron acceptors during respiration. Typical electron acceptors include iron(III) and manganese(IV) oxides, nitrate, selenate, and even carbon dioxide in certain species. This metabolic versatility is mediated by a complex multiheme cytochrome system that transports electrons across the periplasm to external substrates.

Ecologically, Shewanellaceae inhabit marine and freshwater sediments, estuarine environments, and occasionally human-made habitats such as saline brine pools and contaminated aquifers. They play a significant role in biogeochemical cycling of iron and manganese, influencing sediment chemistry and the fate of pollutants. Their capacity to reduce heavy metals and trimethylamine N-oxide makes them valuable in bioremediation strategies for nuclear waste, mining effluents, and waste streams containing organohalides.

The type genus, Shewanella, was first described in 1980 and includes the notable species Shewanella oneidensis MR-1, widely used as a model organism for studying extracellular electron transfer. Genomic analyses reveal large genomes with extensive gene clusters for metal reduction, motility, and stress response. Phylogenetically, Shewanellaceae is closely related to the Desulfuromonadaceae family, sharing common ancestry in the metabolic pathways involved in dissimilatory metal reduction.

Applications of Shewanellaceae extend beyond environmental remediation. Their bioelectricity-generating capacity has inspired the development of microbial fuel cells and nanoscale biosensors. Continued research into their regulatory networks and bioenergetics holds promise for advancing sustainable energy technologies and deepening our understanding of microbial ecology.