Rhizospheric Iron Oxidizing Bacteria from Typha angustifolia Growing in Heavy Metal Enriched Wetlands of Jaduguda Uranium Mine Tailings, India Assisting Phytoremediation by the Plant

Abstract

The Uranium mine tailings of Jaduguda, India is highly contaminated with different heavy metals specially Fe and Mn. Typha angustifolia, a perennial herbaceous plant is the primary vegetation of this heavy metal enriched wetland. This plant exhibits extreme tolerance towards these two heavy metals and is able to sequester about 1000 ppm of Fe in its roots but it does not allow the metal to translocate in the shoot. Thus it decreases the level of iron contamination of the wetland and an important agent for phytoremediation. One of the major causes of iron tolerance of this plant is the formation of Fe plaque on the plant root that imparts permeability to selective metals. Investigation to sort out the mystery behind the formation of this Fe plaque has revealed the presence of Fe oxidizing bacteria at the rhizospheric region of this plant. In this paper we have reported three iron oxidizing rhizospheric bacteria belonging to the genera Bacillus, Paenibacillus and Pseudomonas which are found to play a significant role in regulating the iron accumulation in the roots of Typha and thereby assisting in its natural phytoremediation potential. The role of these microbes in executing iron oxidation (biological oxidation) at the roots of Typha was investigated. Their effect on iron nutrition in Typha under iron replete and excess condition was also evaluated.