Endophytic-Assisted Phytoremediation of Chromium

Abstract

Chromium (Cr) is considered a serious environmental pollutant due to its wide industrial use. Toxicity of Cr to plants depends on its valence state. Cr(VI) is highly toxic and mobile whereas Cr(III) is less toxic. Cr accumulation in plants causes high toxicity in terms of alterations in the germination process, reduction in growth of roots, stems and leaves, which may affect total dry matter production and yield. The present study focused on phytoremediation of chromium through endophytic bacteria. Endophytes were isolated from four plant species growing on heavy metal contaminated soil. Four endophytic bacteria (CEN5, CEN4, CEN3 and CEN2) were selected for phytoremediation experiments. Phytoremediation experiment was carried out by using one hyper accumulator (Brassica napus) and one non hyper accumulator plant (Coriandrum sativum), grown in agricultural soil amended with three different concentrations 50ppm, 100ppm and 200ppm of chromium for 60 days. Inoculation of endophytic strains significantly increased growth of both plants In Brassica napus, endophytic consortia showed maximum root, shoot elongation and vigor index at all concentrations. In Coriandrum sativum CEN5 strain showed maximum root, shoot length and vigour index. Brassica napus with consortia produced maximum fresh and dry biomass. Maximum fresh (25.2g) and dry (14.01g) biomass were produced at 50ppm. The Cr uptake in roots of Brassica napus was 57, 60 and 75%, higher than control at 50, 100 and 200ppm respectively. In shoots of Brassica napus Cr uptake was 52, 57 and 72% higher than control. Coriandrum sativum inoculated with CEN5 accumulated higher Cr in roots and shoots as compared to control. Cr uptake in Brassica napus was higher than Coriandrum sativum. Maximum Cr reduction in Brassica napus was observed with consortia. The maximum reduction in roots and shoots was was upto 80% and 88% respectively. Strain CEN5 showed maximum reduction of in roots and shoots of Coriander sativum. In conclusion endophytes enhanced the plant growth, Cr uptake and reduction from soil contamination. Keyword: Chromium; Phytoremediation; Endophytes; Brassica napus; Coriander sativum, Atomic absorption spectroscopy.