Microbial Characterization of A Chemolithotrophic Bacterial Strain Isolated from Iron Mine Overburden Spoil

The undesirable legacies of iron mining activities lead to unintended consequences in soil subsystem with altered geomorphic system influencing ecosyste m processes. The textural and elemental composition of iron mine spoil with nutrient defici ency determines the characteristic soil microbial communities by providing habitat and nutrient resou rces. Extremities of iron mine overburden spoil allow the existence of specific group of microbial populations especially chemolithotrophs, which reduce Fe 3+ to Fe 2+ thereby influencing the biogeochemistry and minera lization of organic matter. In addition, microbes influence soil functioning du e to their involvement in nutrient cycling, biotransformation, formation of stable microaggrega tes and structural stability. Being the initial colonizers, their presence and activity is crucial for subsequent colonization of other microbial groups in iron mine spoil over time. Therefore, emp hasis has been given to isolate a chemolithotrophic bacterial strain and subsequently characterized and identified by 16S rDNA sequencing. The isolated bacterium was found to be gram-negative, obligatory and facultative chemolithotroph, which exhibited maximal growth in culture medium with pH 9 at 45 o C. The bacterium was observed to be alkalophilic and moder ately thermophilic exhibiting higher growth rate in heterotrophic condition as compared to chem olithotrophic culture condition. Molecular phylogenetic analysis based on 16S rDNA sequence ho mology of the isolated bacterium revealed its close resemblance with Methylobacterium organophilu m DSM 18172T (99% sequence identity), which possess heavy metal resistance genes, regulat ors and metal binding proteins having the ability to survive even in such adverse environmental condi tions.