We expressed and purified an azoreductase homolog, YvaB, from Bacillus subtilis. YvaB was found to have NADH:2,6-dichloroindophenol oxidoreductase activity, as well as azoreductase activity. Purified YvaB was active without FMN, unlike Escherichia coli azoreductase. YvaB was most active at pH 7.5 and 40 C, and was stable up to 55 C after incubation for 30 min. Remarkably, it was stable in the presence of Ag þ , and was activated by the addition of non-ionic detergents. Other enzymatic properties of YvaB were also investigated.