Abstract Shewanella oneidensis is a model species for aquatic ecosystems and plays an important role in bioremediation, biofuel cell manufacturing and biogeochemical cycling. S. oneidensis MR-1 is able to generate hydrogen sulfide from various sulfur species; however, its catalytic kinetics have not been determined. In this study, five in-frame deletion mutants of S. oneidensis were constructed and their H2S-producing activities were analyzed. SirA and PsrA were the two major contributors to H2S generation under anoxic cultivation, and the optimum SO32− concentration for sulfite respiration was approximately 0.8 mM, while the optimum S2O32− concentration for thiosulfate respiration was approximately 0.4 mM. Sulfite and thiosulfate were observed to interfere with each other during respiration, and a high concentration of sulfite or thiosulfate chelated extracellular free-iron but did not repress the expression of sirA or psrA. Nitrite and nitrate were two preferred electron acceptors during anaerobic respiration; however, under energy-insufficient conditions, S. oneidensis could utilize multiple electron acceptors simultaneously. Elucidiating the stoichiometry of H2S production in S. oneidensis would be helpful for the application of this species in bioremediation and biofuel cell manufacturing, and would help to characterize the ecophysiology of sulfur cycling.

中文翻译：

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Shewanella oneidensis在亚硫酸盐和硫代硫酸盐呼吸中产生硫化氢的动力学

摘要 Shewanella oneidensis 是水生生态系统的模式物种，在生物修复、生物燃料电池制造和生物地球化学循环中发挥着重要作用。S. oneidensis MR-1 能够从各种硫物种中生成硫化氢；然而，其催化动力学尚未确定。在这项研究中，构建了五个 S. oneidensis 的框内缺失突变体，并分析了它们的 H2S 产生活性。SirA 和 PsrA 是缺氧培养下 H2S 生成的两个主要贡献者，亚硫酸盐呼吸的最佳 SO32- 浓度约为 0.8 mM，而硫代硫酸盐呼吸的最佳 S2O32- 浓度约为 0.4 mM。观察到亚硫酸盐和硫代硫酸盐在呼吸过程中相互干扰，高浓度的亚硫酸盐或硫代硫酸盐螯合细胞外游离铁，但不抑制 sirA 或 psrA 的表达。亚硝酸盐和硝酸盐是厌氧呼吸过程中两种优选的电子受体；然而，在能量不足的条件下，S. oneidensis 可以同时利用多个电子受体。阐明 S. oneidensis 中 H2S 产生的化学计量将有助于该物种在生物修复和生物燃料电池制造中的应用，并有助于表征硫循环的生态生理学。oneidensis 可以同时利用多个电子受体。阐明 S. oneidensis 中 H2S 产生的化学计量将有助于该物种在生物修复和生物燃料电池制造中的应用，并有助于表征硫循环的生态生理学。oneidensis 可以同时利用多个电子受体。阐明 S. oneidensis 中 H2S 产生的化学计量将有助于该物种在生物修复和生物燃料电池制造中的应用，并有助于表征硫循环的生态生理学。