Comparative Phytoremediation of Heavy Metal Contaminated Sterilized and Unsterilized Soil with Brassica juncea and Bioaugmentation

Abstract

A significant environmental issue is the contamination of the soil and environment by toxic heavy metals and their metabolites. Heavy metals top the list of environmental toxins in terms of their ability to contaminate agricultural soil and water. According to our hypothesis, bacteria are responsible for the increased accumulation of heavy metals by plants. These bacteria can mobilize physiologically inaccessible heavy metal components, modify root exudation, and stimulate plant growth. Rhizosphere microorganisms may extensively mobilize heavy metals, enhancing their bioavailability. This study concentrated on the remediation of Cd and Cu contaminated soil with Brassica juncea. Phytoextraction capabilities of Brassica juncea were compared in sterilized soil with inoculant strains and in unsterilized soil with indigenous bacteria. Pot experiment was conducted with heavy metal contaminated soil from an industrial site. The results revealed that treatment (T7) with sterilized soil, Brassica juncea and Bacillus cereus exhibited maximum extraction of Cu (87.7%). While (T8) with sterilized soil, Brassica juncea, Serratia marcescens and compost amendments exhibited maximum extraction of Cd (57.4%). Maximum root and shoot weight (13.53 g and 1.89 g) was observed in T7. Chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids were also high in T7. Biochemical stress indicators revealed significantly lower levels of APX, GPX, MDA and H2O2 in T7. Bacterial colonization was high in sterilized soil as compared to unsterilized soil. Maximum colony forming units (2.60 x 107 ) were noted in T7. We conclude that sterilized soil with inoculated strains showed better performance as compared to unsterilized soil with indigenous bacteria. It is recommended that integrated approach of bio-augmentation and phytoextraction has a great potential for heavy metal cleanup. Key Words: Phytoremediation, Bioaugmentation, Brassica, Cadmium, Copper, Compost.