China
Africa
Explore chapters and articles related to this topic
Biosynthesis of CdSe Nanoparticles by Anaerobic Granular Sludge
Published in Joyabrata Mal, Microbial Synthesis of Chalcogenide Nanoparticles, 2018
Microbial reduction of selenium-oxyanions (i.e. selenate and selenite) into elemental selenium (Se(0)) and selenide (Se(-II)) plays an important role in the biogeochemical selenium cycling and detoxification of soluble and toxic Se-oxyanions in the natural environment (Dessi et al., 2016; Nancharaiah & Lens, 2015). In environmental settings, selenium is often found as metal selenide minerals in rocks and sediments under highly reducing conditions, but not as elemental selenium (Boyd, 2011; Nancharaiah & Lens, 2015). Selenide can be incorporated into natural sulfide minerals (i.e. pyrite (FeS2), chalcopyrite (CuFeS2), and sphalerite (ZnS)) due to its chemical similarity to sulphur (Nancharaiah & Lens, 2015). To the best of our knowledge, the role of microorganisms in the formation of metal selenides in environmental settings is unknown. Heavy metals like Cd andZn are common co-contaminants found along with selenium oxyanions in different selenium containing waste streams (Mal et al., 2016b). The presence of these heavy metals, either in selenium-rich wastewaters or in environmental settings, may thus influence the microbial reduction processes as well as the speciation of bioreduced selenium (Mal et al., 2016b). Recently, we have reported that the formation of biogenic Se(0) or aqueous selenide (Se(-II)) was influencedby the presence of heavy metals(cadmium, zinc and lead) and their concentration (Mal et al., 2016b). Biogenic Se (Se(0) and Se(-II)) concentrations were found to be higher in the liquid phase when the microbial reduction of selenite was performed in the presence of Cd. One possibility for this observation was the formation of CdSe colloids which can remain in suspension due to their smaller size and surface characteristics. Based on these previous results (Mal et al., 2016b), the present paper focuses on the potential formation of CdSe nanostructures during microbial reduction of selenium oxyanions in the presence of Cd.
Selenium in soil-microbe-plant systems: Sources, distribution, toxicity, tolerance, and detoxification
Published in Critical Reviews in Environmental Science and Technology, 2022
Anamika Kushwaha, Lalit Goswami, Jechan Lee, Christian Sonne, Richard J. C. Brown, Ki-Hyun Kim
Se is often present in rocks and sediments as metal selenide minerals (Madigan et al., 2010). The transformation of Se0 to selenide is not thermodynamically favorable. Few reports on the bacterial reduction of Se oxyanions beyond Se0 are available. Some SeO42−- or SeO32−-respiring bacteria can also reduce Se0 to selenide. Herbel et al. (2003) used axenic bacterial cultures and mixed microbial cultures to reduce Se0 to SeO32− using Se0 as the TEA. Bacillus selenitireducens reduced Se0 or SeO32− to selenide more rapidly when cells were grown on colloidal sulfur instead of fumarate as the electron acceptor