Phyto-rhizoremediation potential of C. zizanioides augmented with Bacillus infantis (VITVJ8) for Heavy metal (Cr, Pb, and Zn) uptake

Jeevanandam Vaishnavi Jabez Osborne ^*

• School of Biosciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, India

The accumulation of heavy metals in the ecosystem due to industrialization has led to the toxic effects on various life forms such as flora, fauna and microfauna. Several approaches that are currently used for the removal of heavy metals are not cost-effective and efficient. Therefore, the current study was focused on the bio-removal of chromium (Cr), Lead (Pb) and zinc (Zn) using augmentation with strong biofilm forming Bacillus infantis (VITVJ8) which was confirmed by Bacillus infantis augmented to the rhizosphere region of Chrysopogon zizanioides with the percentage of 0.025% The bioremoval process was catalysed by superoxide dismutase, chromate reductase and catalase activity with 83U/ml, 51U/ml and 75U/ml respectively. VITVJ8 was also found to be a plant growth promoting bacteria as it was capable of producing Indole Acetic Acid (IAA) 63µg/ml), siderophores 1.238cm and was capable to solubilize insoluble phosphate 72.3%. The bacteria could tolerate Cr and Zn up to 1000 ppm whereas, for Pb it was 1250 ppm. Further, rhizoremediation setup consisting of C. zizanioides augmented with VITVJ8 strain showed enhanced uptake of Zn, Pb and Cr (89% > 86% > 77%) as compared to phytoremediation (60% > 62% > 59%) treated plants. Seed germination assay revealed 75.78% increase in the germination index for set-ups treated with B. infantis, which also confirmed the reduction in heavy metal (HM) toxicity upon treatment with effective strain and enhanced plant growth. Since the uptake was found to be maximum in the roots than the shoots, vetiver can be considered as a root accumulator of Cr, Pb & Zn when amended with B. infantis.