Cr(VI) reduction by a potent novel alkaliphilic halotolerant strain Pseudochrobactrum saccharolyticum LY10

Abstract

A novel Cr(VI)-reducing strain, Pseudochrobactrum saccharolyticum LY10, was isolated and characterized for its high Cr(VI)-reducing ability. Strain LY10 had typical characteristics of alkali-tolerance and halotolerance. Kinetic analysis indicated that the maximum reduction rate was achieved under optimum conditions with initial pH 8.3, 20gL(-1) NaCl, 55mgL(-1) Cr(VI), and 1.47×10(9)cellsmL(-1) of cell concentration. Further mechanism studies verified that the removal of Cr(VI) was mainly achieved by a metabolism-dependent bioreduction process. Strain LY10 accumulated chromium both in and around the cells, with cell walls acting as the major binding sites for chromium. X-ray absorption near-edge structure (XANES) analysis further confirmed that the chromium immobilized by the cells was in the Cr(III) state. In the present study, Pseudochrobactrum saccharolyticum was, for the first time, reported to be a Cr(VI)-reducing bacteria. Results from this research would provide a potential candidate for bioremediation of Cr(VI)-contaminated environments, especially alkaline and saline milieus with Cr(VI) at low-to-mid concentrations.