The present invention provides an enzymatically active composition for suppressing sulfide generation. The composition is free from sulfur dehydrogenase and comprises at least one enzyme having sufficient sulfide-production inhibiting activity in an acidic medium to at least inhibit biogenic sulfide production, and an oxidized nitrogenous inorganic salt present in an amount sufficient to act as an electron acceptor for the enzyme. The oxidized nitrogenous inorganic salt preferably is selected from an alkali metal nitrite, an alkaline earth metal nitrite, an alkali metal nitrate, an alkaline earth metal nitrate, or a mixture of two or more of the foregoing salts. The enzymatically active composition is free from viable bacteria and is non-toxic (i.e., has an oral LD50 in rats greater than 1000 mg/Kg of body weight at a concentration of about 25,000 parts per million (ppm) in water). The compositions of the present invention are useful for treating and removing biofilms, as well as inhibiting sulfide production in a variety of aqueous systems.