Mechanism of Cr(VI) reduction by Lysinibacillus sp. HST-98, a newly isolated Cr (VI)-reducing strain

Abstract

Facing the increasingly severe Cr(VI) pollution, bioreduction has proved to be an eco-friendly remediation method. An isolated strain identified as Lysinibacillus can relatively reduce Cr(VI) well. Even if the concentration of Cr(VI) increased to 250mg/L, the strain HST-98 could also grow and remove Cr(VI) well. After optimization of reaction conditions, the optimal pH, temperature, and electron donor are 8~9, 36°C, and sodium lactate, respectively. Coexisting metal ions such as Cu²⁺, Co²⁺, and Mn²⁺ are beneficial to reduce Cr(VI), while Zn²⁺, Ni²⁺, and Cd²⁺ are just the opposite. What is more, the mechanism of the reduction by the strain HST-98 is chiefly mediated by intracellular enzymes. After gene sequence homology blast and analysis, the genes and enzymes related to chromium metabolism in strain HST-98 have been annotated, which helps us to further understand the reduction mechanism of the strain HST-98. In general, Lysinibacillus sp. HST-98 is a potential candidate to repair the Cr(VI)-contaminated sites.

Keywords: Bioreduction;; Gene annotation; Hexavalent chromium;; Mechanism;.