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Background <p>The highly toxic nature and uncontrolled release of arsenic from anthropogenic activities into ecosystems create a huge health concern globally. Being a class 1 carcinogen, arsenic is affecting billions of people in both developed and developing countries.</p> Results <p><i>Dietzia maris</i> strain sha9 was isolated from industrially contaminated soil, screened phenotypically and genetically, and investigated for its potential in arsenic resistance and bioremediation. Minimum inhibitory concentration assay showed that it can tolerate &lt; 36 mM arsenite and &lt; 185 mM arsenate along with other multiple heavy metals and metalloids, including lead (5 mM), chromium (15 mM), cobalt (10 mM), selenium (7 mM), cadmium 6 mM), mercury (5 mM), and nickel (5 mM). The key genes for arsenic and other heavy metals were identified through whole-genome sequencing, and these genes include <i>aioB</i>,<i> arsC</i>,<i> Acr3</i>,<i> arsR</i>,<i> csoR</i>,<i> copZ</i>, and <i>CzcD</i>. Brownish precipitation upon reaction with AgNO<sub>3</sub> confirmed its oxidizing potential, and the arsenite oxidation potential assay showed 93% oxidizing capacity after 96&#xa0;h. The experiment with wastewater and Milli-Q samples over time demonstrated the functional role of the strain in bioremediation, and the biomass of heat-inactivated cells also has a role in arsenic biosorption. Biochemical characterization highlighted higher intracellular glutathione levels and enhanced antioxidant enzyme activities such as catalase under arsenic stress, demonstrating the triggering of oxidative-stress defense mechanisms in the bacterium. The qPCR analysis further confirmed substantial induction of the <i>aioB</i> gene copy number and expression in the cells exposed to arsenite (almost threefold relative to control), and it is consistent with its pivotal role in the oxidation of arsenic.</p> Conclusion <p>Collectively, these observations proved <i>D. maris</i> strain sha9 is a metabolically adaptable and genetically equipped arsenite-oxidizing bacterium with robust capability for arsenic bioremediation from contaminated sites.</p>

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Unveiling the molecular basis of arsenic resistance in Dietzia maris isolated from arsenic-contaminated soil

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年5月28日

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  • Shahid Sher,
  • Rosny Jean,
  • Zaman Khan,
  • Abdul Rehman

摘要

Background

The highly toxic nature and uncontrolled release of arsenic from anthropogenic activities into ecosystems create a huge health concern globally. Being a class 1 carcinogen, arsenic is affecting billions of people in both developed and developing countries.

Results

Dietzia maris strain sha9 was isolated from industrially contaminated soil, screened phenotypically and genetically, and investigated for its potential in arsenic resistance and bioremediation. Minimum inhibitory concentration assay showed that it can tolerate < 36 mM arsenite and < 185 mM arsenate along with other multiple heavy metals and metalloids, including lead (5 mM), chromium (15 mM), cobalt (10 mM), selenium (7 mM), cadmium 6 mM), mercury (5 mM), and nickel (5 mM). The key genes for arsenic and other heavy metals were identified through whole-genome sequencing, and these genes include aioB, arsC, Acr3, arsR, csoR, copZ, and CzcD. Brownish precipitation upon reaction with AgNO3 confirmed its oxidizing potential, and the arsenite oxidation potential assay showed 93% oxidizing capacity after 96 h. The experiment with wastewater and Milli-Q samples over time demonstrated the functional role of the strain in bioremediation, and the biomass of heat-inactivated cells also has a role in arsenic biosorption. Biochemical characterization highlighted higher intracellular glutathione levels and enhanced antioxidant enzyme activities such as catalase under arsenic stress, demonstrating the triggering of oxidative-stress defense mechanisms in the bacterium. The qPCR analysis further confirmed substantial induction of the aioB gene copy number and expression in the cells exposed to arsenite (almost threefold relative to control), and it is consistent with its pivotal role in the oxidation of arsenic.

Conclusion

Collectively, these observations proved D. maris strain sha9 is a metabolically adaptable and genetically equipped arsenite-oxidizing bacterium with robust capability for arsenic bioremediation from contaminated sites.