Chromium bioremediation by Alcaligenes sp. strain newly isolated from chromite mine of Sabzevar

In this work, CKCr-6A strain was found to be highly resistant to some toxic heavy metals such as Cr+6, Cr+3, Cu+2, Co+2, Cd+2, Pb+2, Hg+2, U+6, tellurium, and selenite. Herein, high chromate tolerance of an isolated strain is reported with a high minimum inhibitory concentration value of 80,000 mg/L and the effective parameters (pH, temperature, shaking, and glucose concentration) were selected for Cr(VI) removal by this isolated strain. Cr(VI) elimination by the target strain increased with glucose addition to the culture medium. We optimized the possible parameters and their interactions using design experimental software. After optimization, this strain showed high efficiency in detoxifying chromate; this could reduce up to 100 mg/L of Cr(VI) to Cr(III) over 3 h. The CKCr-6A strain exhibited ability to in vitro reduction after 3 h and repeated removing of Cr(VI) without any amendment of nutrients, suggesting its possible application in continuous bioremediation.