Microbial heavy metal tolerance in subsurface samples is indicative of long-term ecotoxicological impact of metals and could also reflect metal contamination of groundwater. However, the heavy metal tolerance characteristics of microbes isolated from subsurface river sediment profiles are still obscure. In the present study, determination of heavy metal tolerance of bacterial strains isolated from two Late Quaternary sediment profiles (~ 28 m and ~25 m deep) located at the Mahi river basin, Western India, was carried out. Identification of bacterial isolates by the 16S rRNA gene sequencing revealed that bacterial isolates affiliated with phyla Actinobacteria, Proteobacteria, Firmicutes, and Bacteroidetes were dominant in both sediment profiles. Heavy metal tolerance of bacterial strains as determined by plate diffusion assay revealed order of metal tolerance as follows: Hg(II)<Cd(II)< Ni(II)<Cu(II)=Cr(VI). Chromate removal study in liquid medium suggested that bacterial strains procured from subsurface possessed the ability to remove Cr(VI) with varied magnitude. A packed bed column experiment indicated that bacterial strains obtained from the subsurface have the potential for Cr(VI) removal from different particle size consistencies of the sediments.

地下样品中的微生物重金属耐受性表明金属的长期生态毒理学影响，也可以反映地下水的金属污染。然而，从地下河流沉积物剖面中分离出的微生物的重金属耐受性特征仍不清楚。在本研究中，确定了从位于印度西部马希河流域的两个晚第四纪沉积物剖面（~28 m 和~25 m 深）中分离的细菌菌株的重金属耐受性。通过 16S rRNA 基因测序鉴定细菌分离物表明，隶属于放线菌门、变形菌门、厚壁菌门和拟杆菌门的细菌分离物在两种沉积物剖面中均占优势。通过平板扩散试验测定的细菌菌株的重金属耐受性揭示金属耐受性的顺序如下：Hg(II)<Cd(II)<Ni(II)<Cu(II)=Cr(VI)。液体介质中的铬酸盐去除研究表明，从地下获得的细菌菌株具有去除不同量级 Cr(VI) 的能力。填充床柱实验表明，从地下获得的细菌菌株具有从不同粒度浓度的沉积物中去除 Cr(VI) 的潜力。