Assessment of plant growth promotion properties and impact of Microbacterium foliorum for arsenic removal in Melastoma malabathricum

The Microbacterium foliorum species is known for its ability to produce siderophores which, in synergy with the plant root, can effectively affect the rates of arsenate-to-arsenite mobilization, arsenic uptake, and translocation. This study investigates M. foliorum, a plant growth-promoting bacterium (PGPB), in the absorption of arsenic (As) by Melastoma malabathricum plant from contaminated soil. The current study demonstrates M. foliorum phytoremediation's efficacy in terms of As tolerance, removal, and toxicity in the M. malabathricum plant. For an observation period of 90 days, growing plants were treated with M. foliorum in arsenic-contaminated soil. The morphological trait, pH of soil, and potential advantage induced by M. foliorum on M. malabathricum were evaluated. Plants did not display any noticeable signs of toxicity, however, the root and stem length were significantly increased in the presence of M. foliorum. The Bioconcentration Factor (BCF) was increased in plants inoculated with M. foliorum by 0.3 times, the Transfer Factor (TF) of As in the M. malabathricum plants decreased, whether in the presence or absence of PGPB. The As phytoremediation treatment with M. foliorum also enhanced uptake of As in root (by 26%) and shoot (by 22%) than in the other two (A2 and control) phytoremediation treatments. This shows that M. foliorum inoculation reduced As toxicity through substantial reduction of the adverse stress effects, increased stem and root fresh and dry weight.