海水养殖生境中硫酸盐还原菌活性的抑制机制

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

摘要:

【目的】海水养殖生境中的硫化物(H₂S)严重损害养殖生物健康，控制该条件下硫酸盐还原菌(sulfate-reducing bacteria，SRB)的代谢活性是有效抑制H₂S产生的重要途径。【方法】本研究利用稀释涂布-叠皿夹法对海水养殖生境底泥中SRB进行富集筛选，获得SRB菌株，通过投加硝酸盐对菌株产H₂S的活性进行抑制。【结果】获得的2株SRB Desulfovibrio sp.NY-1和Clostridium sp.NH-1，能够在35℃、pH为7.0及盐度为20–30 mg/L条件下，分别积累高达435和150 mg/L H₂S。硝酸盐不能有效抑制NY-1产H₂S的活性，基因调控作用以及缺乏将硝酸盐作为电子受体的酶体系是其不能被抑制的主要原因。硝酸盐对NH-1 H₂S产生活性有可逆性抑制，其具有硝酸盐异化还原成铵(dissimilatory nitrate reduction to ammonium，DNRA)的能力，优先利用硝酸盐作为电子受体。DNRA作用下的中间代谢产物亚硝酸盐是有效抑制菌株NH-1产H₂S活性的主要原因，其抑制机理主要为抑制菌株的生长繁殖。【结论】硝酸盐对不同SRB菌株具有不同的抑制机制和效果，在进行硫化物污染控制前需要对产生硫化物的SRB菌群进行分析判别。

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.