TheShewanellagenus: ubiquitous organisms sustaining and preserving aquatic ecosystems

Abstract

The Gram-negative Shewanella bacterial genus currently includes about 70 species of mostly aquatic γ­-proteobacteria, which were isolated around the globe in a multitude of environments such as surface freshwater and the deepest marine trenches. Their survival in such a wide range of ecological niches is due to their impressive physiological and respiratory versatility. Some strains are among the organisms with the highest number of respiratory systems, depending on a complex and rich metabolic network. Implicated in the recycling of organic and inorganic matter, they are important components of organism-rich oxic/anoxic interfaces, but they also belong to the microflora of a broad group of eukaryotes from metazoans to green algae. Examples of long-term biological interactions like mutualism or pathogeny have been described, although molecular determinants of such symbioses are still poorly understood. Some of these bacteria are key organisms for various biotechnological applications, especially the bioremediation of hydrocarbons and metallic pollutants. The natural ability of these prokaryotes to thrive and detoxify deleterious compounds explains their use in wastewater treatment, their use in energy generation by microbial fuel cells and their importance for resilience of aquatic ecosystems.

Characterization of putative pathogenic Shewanella algae isolated from ballast water

“…The capability of all S. algae isolates in this study to produce extracellular enzymes such as lipase, protease, DNase, and hemolysin could be inferred as part of adaptive mechanism for the species to survive in their respective marine environment. The expression of this phenotype could be aimed at reducing surrounding microbial competition or degrading organic matter to gain access to their nutrients [20,56]. However, the adaptation allowing survival in marine environment could also allow for colonization of living hosts if the bacteria get the opportunity to enter the host.…”

“…S. algae has been recognized as a conditionally pathogenic bacteria to human and aquatic animals [19,20]. The most common clinical symptoms described in human infections by S. algae are bacteremia, cellulitis, and chronic otitis media [18].…”

Regeneration of unconventional natural gas by methanogens co-existing with sulfate-reducing prokaryotes in deep shale wells in China

“…Thus the abnormal increase/decrease of Shewanella sp. could be proposed to be a biomarker to detect alteration of such special ecosystems in shale-gas wells 39 . Except for Shewanella group, Geobacter was www.nature.com/scientificreports/ another dominant metal-reducing genus which was found in other shale-gas wells recently 12 .…”

Free Rather Than Total Iron Content Is Critically Linked to the Fur Physiology in Shewanella oneidensis

“…Shewanella, a group of facultative dissimilatory metalreducing γ-proteobacteria, have attracted interest for their ability to reduce a wide array of electron acceptors (EAs), and they now serve as a genetic model for studying microbial electrosynthesis (Fredrickson et al, 2008;Rabaey and Rozendal, 2010;Lemaire et al, 2020). The respiratory versatility is attributable to a large repertoire of iron-containing proteins, including hundreds having heme, Fe-S clusters as cofactors, and a dozen or so using iron atom directly to execute catalysis (Imlay, 2014).…”