Sulfide-producing activity inhibition of sulfate-reducing bacteria in mariculture

Abstract:

[Objective] Sulphide (H₂S) in mariculture seriously damages the health of cultured organisms. Controlling the metabolic activity of sulfate-reducing bacteria (SRB) in mariculture is an effective way to inhibit H₂S production. [Methods] In this study, SRB strains were enriched and isolated from the mariculture sediments via dilution coating-repeat dish sandwish cultivation method. The H₂S activity was inhibited by adding nitrate. [Results] Two SRB strains Desulfovibrio sp. NY-1 and Clostridium sp. NH-1 were isolated, which respectively accumulated up to 435 and 150 mg/L H₂S at 35℃, pH 7.0, and salinity of 20-30 mg/L. The H₂S activity of NY-1 was not effectively inhibited by nitrate, which was related to the gene regulation and the lack of the enzyme system using nitrate as the electron acceptor. Nitrate reversibly inhibited the H₂S activity of NH-1 which had the ability of dissimilatory nitrate reduction to ammonium (DNRA) and preferentially used nitrate as the electron acceptor. Nitrite, the intermediate metabolite of DNRA, was the main factor for inhibiting the H₂S production activity of NH-1 since it can inhibit the growth and reproduction of the strain. [Conclusion] The inhibition mechanisms and effects of nitrate vary among different SRB strains. Before controlling sulfide pollution, we need to analyze and distinguish the sulfide-producing bacteria.