Selenium Metabolizing Capabilities of 12 Bacterial Strains Isolated from Urban Environmental Samples

The role of bacterial selenium metabolism in non-polluted environments remains underexplored within the selenium biogeochemical cycle. In this study, selenium-metabolizing bacteria were isolated from urban environmental samples. Among 12 isolates, 10 were identified as <i data-eusoft-scrollable-e...

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Main Authors: Masashi Kuroda, Iori Ishimoto, Chisato Kameoka, Toshiki Kawanishi, Ren Saito, Hajime Toki, Hiroya Yamagishi, Yuzuki Watanabe, Yukinori Tani
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Microorganisms
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Online Access:https://www.mdpi.com/2076-2607/13/7/1675
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Summary:The role of bacterial selenium metabolism in non-polluted environments remains underexplored within the selenium biogeochemical cycle. In this study, selenium-metabolizing bacteria were isolated from urban environmental samples. Among 12 isolates, 10 were identified as <i data-eusoft-scrollable-element="1">Citrobacter</i> spp., while the remaining 2 were <i data-eusoft-scrollable-element="1">Scandinavium hiltneri</i> and <i data-eusoft-scrollable-element="1">Klebsiella aerogenes</i>. The <i data-eusoft-scrollable-element="1">Citrobacter</i> isolates demonstrated high selenium-removal efficiency, removing over 95% of 5 mM selenium from the aqueous phase within one week. In contrast, <i data-eusoft-scrollable-element="1">S. hiltneri</i> K24-1 and <i data-eusoft-scrollable-element="1">K. aerogenes</i> K24-4 removed only 19% and 69%, respectively. A detailed investigation of five representative isolates, <i data-eusoft-scrollable-element="1">C. freundii</i> K21-1, <i data-eusoft-scrollable-element="1">S. hiltneri</i> K24-1, <i data-eusoft-scrollable-element="1">C. braakii</i> K24-2, <i data-eusoft-scrollable-element="1">K. aerogenes</i> K24-4, and <i data-eusoft-scrollable-element="1">C. freundii</i> K24-5, revealed that <i data-eusoft-scrollable-element="1">Citrobacter</i> spp. efficiently reduced selenate directly to elemental selenium, with minimal accumulation of selenite intermediates. These results highlight <i data-eusoft-scrollable-element="1">Citrobacter</i> spp. as key selenium reducers and suggest their potential as bioindicators of selenium metabolic capacity in the environment.
ISSN:2076-2607