Abstract:

A bacterial strain exhibiting strong manganese （Mn） tolerance was isolated from paddy soil surrounding a uranium mine using the enrichment culture method and designated as NM3. The bacterium was identified as belonging to the Enterobacter genus through colony morphology， Gram staining， and 16S rDNA sequence analysis. To investigate the adsorption efficiency of Mn²⁺ by the NM3 strain and the associated adsorption mechanisms， we employed atomic absorption spectroscopy， scanning electron microscopy， and Fourier-transform infrared spectroscopy for comprehensive analysis. The results indicated that the strain tolerated Mn²⁺ concentrations of up to 8 000 mg·L^-1. After a 60-hour reaction period at a Mn²⁺ concentration of 4 000 mg·L^-1， the removal rate reached 93.3%. The primary functional groups involved in this adsorption process were identified as hydroxyl， alkyl， and amide groups. Further evaluation of the growth-promoting properties of the NM3 strain and its impact on Mn²⁺ accumulation in green vegetables revealed that the strain produced auxin indole-3-acetic acid （IAA）， which significantly enhanced the biomass of green vegetables under Mn stress， with increases ranging from 34.13% to 56.09%. Additionally， the Mn²⁺ content in the green vegetables decreased by 50.09%. In summary， the NM3 strain not only demonstrates high tolerance and strong adsorption capacity but also represents a promising new microbial resource for mitigating soil Mn pollution， thereby ensuring vegetable safety.

Key words: manganese resistant bacteria, removal rate, plant promotion, manganese adsorptions