Paenibacillus lentimorbus enhances growth of chickpea (Cicer arietinum L.) in chromium-amended soil.

Chromium (Cr), with its great economic importance in industrial use, is a major metal pollutant of the environment. It affects soil microbial activity and soil fertility, resulting in losses in yield of plants. Paenibacillus lentimorbus B-30488(r) (B-30488(r)) tolerated 200 μg ml(-1) of Cr under in vitro conditions and produced the plant growth promoting substance indole acetic acid in the presence of Cr. Our in vitro study indicates enhancement in B-30488(r) biofilm formation by sodium alginate (SA) and calcium chloride (CaCl(2)) both in absence and presence of supplemented Cr(VI) as compared to unsupplemented control. The plant growth promoting effects caused by the B-30488(r) biofilm in rhizosphere of chickpea under Cr(VI) stress suggests a phytoprotective role of B-30488(r) biofilm. Our study reflects the multifarious role of strain B-30488(r) and presents it as a potent plant growth promoting and bioremediation agent useful in Cr-contaminated rhizosphere soil, whereby the SA and CaCl(2) induced B-30488(r) biofilm on plant root acts as a shield in preventing the direct access of toxic Cr to plant tissues, thus reducing its uptake in plants.