The Environmental Biotechnology Lab

Inhibition of sulfide production by sulfate-reducing bacteria can be achieved by the use of chemical agents such as nitrite, molybdate, or copper. Herein, we tested the effect of these biocides and their combinations on the growth and production of H₂S by Desulfovibrio vulgaris subsp. vulgaris. At pH 6.6, lower concentrations of biocides were required to inhibit H₂S production in comparison to pH 7.8, as a consequence of higher production rates of bactericidal nitrous acid, or lower formation rates of thiomolybdate. A combination of 0.1 mM MoO₄ ²⁻ and 0.25 mM NO₂ ⁻ at pH 7.8 was found to be synergistic, leading to an inhibition rate of 56% in H₂S production and of 85% in D. vulgaris growth.