Potential Self-Attenuation of Arsenic by Indigenous Microorganisms in the Nakdong River
The toxic element arsenic (As) has become the major focus of global research owing to its harmful effects on human health, resulting in the establishment of several guidelines to prevent As contamination. The widespread industrial use of As has led to its accumulation in the environment, increasing...
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| Format: | Article |
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MDPI AG
2023-07-01
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| Series: | Microorganisms |
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| Online Access: | https://www.mdpi.com/2076-2607/11/8/1910 |
| _version_ | 1797583783794311168 |
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| author | Sangmin Won Chajeong Shin Ho Young Kang |
| author_facet | Sangmin Won Chajeong Shin Ho Young Kang |
| author_sort | Sangmin Won |
| collection | DOAJ |
| description | The toxic element arsenic (As) has become the major focus of global research owing to its harmful effects on human health, resulting in the establishment of several guidelines to prevent As contamination. The widespread industrial use of As has led to its accumulation in the environment, increasing the necessity to develop effective remediation technologies. Among various treatments, such as chemical, physical, and biological treatments, used to remediate As-contaminated environments, biological methods are the most economical and eco-friendly. Microbial oxidation of arsenite (As(III)) to arsenate (As(V)) is a primary detoxification strategy for As remediation as it reduces As toxicity and alters its mobility in the environment. Here, we evaluated the self-detoxification potential of microcosms isolated from Nakdong River water by investigating the autotrophic and heterotrophic oxidation of As(III) to As(V). Experimental data revealed that As(III) was oxidized to As(V) during the autotrophic and heterotrophic growth of river water microcosms. However, the rate of oxidation was significantly higher under heterotrophic conditions because of the higher cell growth and density in an organic-matter-rich environment compared to that under autotrophic conditions without the addition of external organic matter. At an As(III) concentration > 5 mM, autotrophic As(III) oxidation remained incomplete, even after an extended incubation time. This inhibition can be attributed to the toxic effect of the high contaminant concentration on bacterial growth and the acidification of the growth medium with the oxidation of As(III) to As(V). Furthermore, we isolated representative pure cultures from both heterotrophic- and autotrophic-enriched cultures. The new isolates revealed new members of As(III)-oxidizing bacteria in the diversified bacterial community. This study highlights the natural process of As attenuation within river systems, showing that microcosms in river water can detoxify As under both organic-matter-rich and -deficient conditions. Additionally, we isolated the bacterial strains HTAs10 and ATAs5 from the microcosm which can be further investigated for potential use in As remediation systems. Our findings provide insights into the microbial ecology of As(III) oxidation in river ecosystems and provide a foundation for further investigations into the application of these bacteria for bioremediation. |
| first_indexed | 2024-03-10T23:43:55Z |
| format | Article |
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| institution | Directory Open Access Journal |
| issn | 2076-2607 |
| language | English |
| last_indexed | 2024-03-10T23:43:55Z |
| publishDate | 2023-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Microorganisms |
| spelling | doaj.art-b3d69c5b82e64f8bb834d4fbe97c09682023-11-19T02:15:53ZengMDPI AGMicroorganisms2076-26072023-07-01118191010.3390/microorganisms11081910Potential Self-Attenuation of Arsenic by Indigenous Microorganisms in the Nakdong RiverSangmin Won0Chajeong Shin1Ho Young Kang2Department of Microbiology, Pusan National University, Busan 46241, Republic of KoreaBUSAN IL Science Highschool, Busan 49317, Republic of KoreaDepartment of Microbiology, Pusan National University, Busan 46241, Republic of KoreaThe toxic element arsenic (As) has become the major focus of global research owing to its harmful effects on human health, resulting in the establishment of several guidelines to prevent As contamination. The widespread industrial use of As has led to its accumulation in the environment, increasing the necessity to develop effective remediation technologies. Among various treatments, such as chemical, physical, and biological treatments, used to remediate As-contaminated environments, biological methods are the most economical and eco-friendly. Microbial oxidation of arsenite (As(III)) to arsenate (As(V)) is a primary detoxification strategy for As remediation as it reduces As toxicity and alters its mobility in the environment. Here, we evaluated the self-detoxification potential of microcosms isolated from Nakdong River water by investigating the autotrophic and heterotrophic oxidation of As(III) to As(V). Experimental data revealed that As(III) was oxidized to As(V) during the autotrophic and heterotrophic growth of river water microcosms. However, the rate of oxidation was significantly higher under heterotrophic conditions because of the higher cell growth and density in an organic-matter-rich environment compared to that under autotrophic conditions without the addition of external organic matter. At an As(III) concentration > 5 mM, autotrophic As(III) oxidation remained incomplete, even after an extended incubation time. This inhibition can be attributed to the toxic effect of the high contaminant concentration on bacterial growth and the acidification of the growth medium with the oxidation of As(III) to As(V). Furthermore, we isolated representative pure cultures from both heterotrophic- and autotrophic-enriched cultures. The new isolates revealed new members of As(III)-oxidizing bacteria in the diversified bacterial community. This study highlights the natural process of As attenuation within river systems, showing that microcosms in river water can detoxify As under both organic-matter-rich and -deficient conditions. Additionally, we isolated the bacterial strains HTAs10 and ATAs5 from the microcosm which can be further investigated for potential use in As remediation systems. Our findings provide insights into the microbial ecology of As(III) oxidation in river ecosystems and provide a foundation for further investigations into the application of these bacteria for bioremediation.https://www.mdpi.com/2076-2607/11/8/1910heterotrophic bacteriaautotrophic bacteriafreshwaterarsenicmicrobial oxidation |
| spellingShingle | Sangmin Won Chajeong Shin Ho Young Kang Potential Self-Attenuation of Arsenic by Indigenous Microorganisms in the Nakdong River Microorganisms heterotrophic bacteria autotrophic bacteria freshwater arsenic microbial oxidation |
| title | Potential Self-Attenuation of Arsenic by Indigenous Microorganisms in the Nakdong River |
| title_full | Potential Self-Attenuation of Arsenic by Indigenous Microorganisms in the Nakdong River |
| title_fullStr | Potential Self-Attenuation of Arsenic by Indigenous Microorganisms in the Nakdong River |
| title_full_unstemmed | Potential Self-Attenuation of Arsenic by Indigenous Microorganisms in the Nakdong River |
| title_short | Potential Self-Attenuation of Arsenic by Indigenous Microorganisms in the Nakdong River |
| title_sort | potential self attenuation of arsenic by indigenous microorganisms in the nakdong river |
| topic | heterotrophic bacteria autotrophic bacteria freshwater arsenic microbial oxidation |
| url | https://www.mdpi.com/2076-2607/11/8/1910 |
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