Bioremediation Potential of Rhodococcus qingshengii PM1 in Sodium Selenite-Contaminated Soil and Its Impact on Microbial Community Assembly

Summary

This study investigated how a bacterium called Rhodococcus qingshengii PM1 can help clean up soil contaminated with selenium, a toxic element that accumulates in food chains. Using advanced genetic sequencing, researchers found that this bacterium can break down toxic selenite compounds by 63-71% within three weeks, which is much faster than natural processes. Adding the bacteria to contaminated soil also helped restore the diversity and health of the natural soil microbial communities, making it a promising tool for environmental cleanup efforts.

Background

Selenium contamination in soil poses significant environmental and health risks, primarily through agricultural runoff, mining activities, and industrial discharges. Soil microbial communities are particularly sensitive to selenium contamination and serve as effective indicators of ecological impacts. Microbial bioremediation has emerged as a promising approach to transform toxic selenite into less harmful forms.

Objective

This study aimed to examine the effects of low and high doses of sodium selenite and the selenite-degrading bacterium Rhodococcus qingshengii PM1 on soil bacterial community composition, diversity, and assembly processes. The researchers hypothesized that PM1 inoculation would enhance microbial diversity and community complexity while reducing selenium contamination.

Results

Sodium selenite and strain PM1 were identified as key predictors of bacterial community structure, with selenite initially reducing microbial diversity and shifting dominant bacterial groups. PM1 inoculation enhanced selenite degradation by 63-71% within 20 days compared to 8-17% in untreated soils. Stochastic processes dominated community assembly, with heterogeneous selection and drift being primary drivers of community turnover.

Conclusion

Strain PM1 demonstrated robust bioremediation potential, partially reversing negative effects of selenium contamination by enhancing community complexity and promoting species dispersal. The findings provide insights into microbial community assembly mechanisms under selenium stress and support the practical application of R. qingshengii PM1 for bioremediation of selenium-contaminated soils.
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