Impact of heavy metals on the rhizosphere microflora of Jatropha multifida and their effective remediation

Abstract

The impact of heavy metals (arsenic, chromium, copper and magnesium) in the rhizosphere microflora of Jatropha multifida used for phytoremediation was studied. The pot culture experiment of J. multifida dealt with the biochemical characteristics of heavy metals contaminated soil amended with waste water biosludge and biofertilizer (Azotobacter vinelandii). Plant growth promoting rhizobacteria such as Pseudomonas, Azotobacter and Rhizobium were isolated, characterized and screened for their heavy metal tolerance. Pseudomonas was found to be the most tolerant followed by Azotobacter and Rhizobium. Amongst heavy metals, As was most toxic followed by Cr, Mg and Cu. Amongst different soil treatments, T4 (garden soil with heavy metal, biosludge, and biofertilizer) served the best treatment for plants and microbial endurance under metal contamination. The results advocate that the toxicity of heavy metals in soil can be restored with concomitant amendment of organic sludge and appropriate biofertilizer.

Key words: Heavy metals, rhizosphere, biosludge, biofertilizer, bioremediation.