Abstract: A azoreductase gene with 537 bp was obtained by PGR amplification
from Rhodobacter sphaeroides AS1.1737. The enzyme, with a molecular weight of
18.7 kD, was efficiently expressed in Escherichia coli and its biodegradation
characteristics for azo dyes were investigated. Furthermore, the reaction
kinetics and mechanism of azo dyes catalyzed by the genetically engineered
azoreductase were studied in detail. The presence of a hydrazo-intermediate was
identified, which provided a convincing evidence for the assumption that azo
dyes were degraded via an incomplete reduction stage.