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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author Masashi Kuroda
Iori Ishimoto
Chisato Kameoka
Toshiki Kawanishi
Ren Saito
Hajime Toki
Hiroya Yamagishi
Yuzuki Watanabe
Yukinori Tani
author_facet Masashi Kuroda
Iori Ishimoto
Chisato Kameoka
Toshiki Kawanishi
Ren Saito
Hajime Toki
Hiroya Yamagishi
Yuzuki Watanabe
Yukinori Tani
author_sort Masashi Kuroda
collection DOAJ
description 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.
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issn 2076-2607
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spelling doaj-art-93c379ecd2594ebdbdff10ec43f2afcf2025-08-20T02:47:19ZengMDPI AGMicroorganisms2076-26072025-07-01137167510.3390/microorganisms13071675Selenium Metabolizing Capabilities of 12 Bacterial Strains Isolated from Urban Environmental SamplesMasashi Kuroda0Iori Ishimoto1Chisato Kameoka2Toshiki Kawanishi3Ren Saito4Hajime Toki5Hiroya Yamagishi6Yuzuki Watanabe7Yukinori Tani8Faculty of Social and Environmental Studies, Tokoha University, 6-1 Yayoi-cho, Shizuoka 422-8581, JapanFaculty of Social and Environmental Studies, Tokoha University, 6-1 Yayoi-cho, Shizuoka 422-8581, JapanFaculty of Social and Environmental Studies, Tokoha University, 6-1 Yayoi-cho, Shizuoka 422-8581, JapanFaculty of Social and Environmental Studies, Tokoha University, 6-1 Yayoi-cho, Shizuoka 422-8581, JapanFaculty of Social and Environmental Studies, Tokoha University, 6-1 Yayoi-cho, Shizuoka 422-8581, JapanFaculty of Social and Environmental Studies, Tokoha University, 6-1 Yayoi-cho, Shizuoka 422-8581, JapanFaculty of Social and Environmental Studies, Tokoha University, 6-1 Yayoi-cho, Shizuoka 422-8581, JapanFaculty of Social and Environmental Studies, Tokoha University, 6-1 Yayoi-cho, Shizuoka 422-8581, JapanDepartment of Environmental Health Sciences, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, JapanThe 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.https://www.mdpi.com/2076-2607/13/7/1675selenium metabolismbiogeochemical cycle of selenium<i>Citrobacter</i> spp.
spellingShingle Masashi Kuroda
Iori Ishimoto
Chisato Kameoka
Toshiki Kawanishi
Ren Saito
Hajime Toki
Hiroya Yamagishi
Yuzuki Watanabe
Yukinori Tani
Selenium Metabolizing Capabilities of 12 Bacterial Strains Isolated from Urban Environmental Samples
Microorganisms
selenium metabolism
biogeochemical cycle of selenium
<i>Citrobacter</i> spp.
title Selenium Metabolizing Capabilities of 12 Bacterial Strains Isolated from Urban Environmental Samples
title_full Selenium Metabolizing Capabilities of 12 Bacterial Strains Isolated from Urban Environmental Samples
title_fullStr Selenium Metabolizing Capabilities of 12 Bacterial Strains Isolated from Urban Environmental Samples
title_full_unstemmed Selenium Metabolizing Capabilities of 12 Bacterial Strains Isolated from Urban Environmental Samples
title_short Selenium Metabolizing Capabilities of 12 Bacterial Strains Isolated from Urban Environmental Samples
title_sort selenium metabolizing capabilities of 12 bacterial strains isolated from urban environmental samples
topic selenium metabolism
biogeochemical cycle of selenium
<i>Citrobacter</i> spp.
url https://www.mdpi.com/2076-2607/13/7/1675
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