Enzymatic Reduction of Hexavalent Chromium by Hexavalent Chromium Tolerant Pseudomonas ambigua G-1

Abstract

When hexavalent chromium (Cr⁶⁺) tolerant Pseudomonas ambigua G-1 was cultivated in nutrient broth containing 150ppm Cr⁶⁺, the Cr⁶⁺ content of the broth rapidly decreased. The Cr⁶⁺ reducing enzyme found in a cell-free extract of P. ambigua G-1 required NADH but not NADPH as a hydrogen donor for the reduction of Cr⁶⁺. The specific activities of cell-free extracts of several Cr⁶⁺ sensitive mutants derived from P. ambigua G-1 showed decreases to one fourth to one tenth of that of P. ambigua G-1. Glucose protected the Cr⁶⁺ reducing enzyme against inactivation on dialysis.