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Bioreduction of chromium (VI) to chromium (III) by a novel yeast strain <i>Rhodotorula mucilaginosa</i> (MTCC 9315)
Abstract
Introduction of heavy metal compounds like chromium, lead, arsenic and mercury into the environment generally induces morphological and physiological changes in the microbial communities hence exerting a selective pressure on the microorganisms. Generally, sites which are contaminated with heavy metals are the sources of metal resistant microorganisms. This paper describes the bioreduction of Cr6+ to Cr3+ by a novel strain Rhodotorula mucilaginosa (MTCC 9315). The yeast is very efficient in Cr6+ reduction. It is shown that the reduction of Cr6+ to Cr3+ species occurs extracellularly by analyzing the supernatant of the yeast extract peptone sucrose medium (YEPS) thus supporting the assumption about the existence of an extra-cellular pathway of Cr6+ reduction. Furthermore, it is demonstrated that R. mucilaginosa cells are salt tolerant. It is thus suggested that isolated yeast biomass can be used as sources of Cr6+ reducer, and the resin formulated in the present study may be used as biofilter to filter out Cr6+ ions. The yeast can also be a good supplier of Cr-chelators with potential pharmacological applications.
Keywords: Chromium bioreduction, resin, industrial effluent, metal resistant microorganisms, yeast, biofilter