Identification of Anaerobic Selenate-Respiring Bacteria from Aquatic Sediments

Abstract

The diversity population of microorganisms with the capability to use selenate as a terminal electron acceptor, reducing it to selenite and elemental selenium by the process known as dissimilatory selenate reduction, is largely unknown. The overall objective of this study was to gain an in-depth understanding of anaerobic biotransformation of selenium in the environment, particularly anaerobic respiration, and to characterize the microorganisms catalyzing this process. Here, we demonstrate the isolation and characterization of four novel anaerobic dissimilatory selenate-respiring bacteria enriched from a variety of sources, including sediments from three different water bodies in Chennai, India, and a tidal estuary in New Jersey. Strains S5 and S7 from India, strain KM from the Meadowlands, NJ, and strain pn1, categorized as a laboratory contaminant, were all phylogenetically distinct, belonging to various phyla in the bacterial domain. The 16S rRNA gene sequence shows that strain S5 constitutes a new genus belonging to Chrysiogenetes, while strain S7 belongs to the Deferribacteres, with greater than 98% 16S rRNA gene similarity to Geovibrio ferrireducens. Strain KM is related to Malonomonas rubra, Pelobacter acidigallici, and Desulfuromusa spp., with 96 to 97% 16S rRNA gene similarity. Strain pn1 is 99% similar to Pseudomonas stutzeri. Strains S5, S7, and KM are obligately anaerobic selenate-respiring microorganisms, while strain pn1 is facultatively anaerobic. Besides respiring selenate, all these strains also respire nitrate.

Secondary Mineralization of Ferrihydrite Affects Microbial Methanogenesis in Geobacter-Methanosarcina Cocultures

“…Ferrihydrite reduction was coupled to acetate/ethanol utilization; approximately 2.4 mM acetate and 1.5 mM ethanol were consumed in the G. sulfurreducens cultures and the G. metallireducens cultures, respectively (see Fig. S1B Tables S1 and S2 in the supplemental material), similar to values observed previously during dissimilatory selenate reduction (25). A portion of the carbon was assimilated by the microbial cells.…”

Ecology and Biotechnology of Selenium-Respiring Bacteria

“…These bacteria were isolated from the Arthur Kill and the Kesterson Reservoir (28). Narasingarao and Häggblom enriched and isolated dissimilatory SeO 4 2Ϫ -respiring bacteria from geographically and characteristically different sediment samples from Chennai (India) and New Jersey by using SeO 4 2Ϫ as the sole terminal electron acceptor (47,48). Four bacterial strains were isolated that could grow via dissimilatory SeO 4 2Ϫ respiration and belonged to metabolically and taxonomically diverse taxa of the Gammaproteobacteria, Deltaproteobacteria, Deferribacteres, and Chrysiogenetes.…”

Anodic and cathodic microbial communities in single chamber microbial fuel cells

“…3). This genus is characterized by gram-negative, strictly anaerobe bacteria able to couple the oxidation of acetate to Fe(III), S 0 , Co(III) and Se(VI) reduction [25,35]. Geovibrio genus is not related to the other metal reducing bacteria in Proteobacteria phylum and forms a separate line [36].…”