Härtig Cornelia, Lohmayer Regina, Kolb Steffen, Horn Marcus A, Inskeep William P, Planer-Friedrich Britta
Department of Environmental Geochemistry, Bayreuth Center for Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany.
FEMS Microbiol Ecol. 2014 Dec;90(3):747-60. doi: 10.1111/1574-6941.12431. Epub 2014 Oct 10.
Novel insights are provided regarding aerobic chemolithotrophic growth of Thermocrinis ruber OC14/7/2 on the electron donors arsenite and monothioarsenate. Thermocrinis ruber is a hyperthermophilic bacterium that thrives in pH-neutral to alkaline hot springs and grows on hydrogen, elemental sulfur, and thiosulfate. Our study showed that T. ruber can also utilize arsenite as sole electron donor producing arsenate. Growth rates of 0.024 h(-1) were lower than for oxidation of thiosulfate to sulfate (μ = 0.247 h(-1)). Fast growth was observed on monothioarsenate (μ = 0.359 h(-1)), comprising different abiotic and biotic redox interactions. The initial dominant process was abiotic transformation of monothioarsenate to arsenate and elemental sulfur, followed by microbial oxidation of sulfur to sulfate. Elevated microbial activity during stationary growth of T. ruber might be explained by microbial oxidation of thiosulfate and arsenite, both also products of abiotic monothioarsenate transformation. However, the observed rapid decrease of monothioarsenate, exceeding concentrations in equilibrium with its products, also indicates direct microbial oxidation of arsenic-bond S(-II) to sulfate. Free sulfide was oxidized abiotically too fast to play a role as electron donor for T. ruber. Our present laboratory and previous field studies suggest that thioarsenates can either indirectly or directly be used by (hyper)thermophiles in arsenic-sulfidic environments.
本文提供了关于嗜热栖热放线菌OC14/7/2在电子供体亚砷酸盐和一硫代亚砷酸盐上进行好氧化能无机营养生长的新见解。嗜热栖热放线菌是一种嗜热细菌，在pH值中性至碱性的温泉中生长旺盛，能利用氢气、元素硫和硫代硫酸盐进行生长。我们的研究表明，嗜热栖热放线菌还能利用亚砷酸盐作为唯一电子供体产生砷酸盐。其生长速率为0.024 h⁻¹，低于硫代硫酸盐氧化为硫酸盐的速率（μ = 0.247 h⁻¹）。在一硫代亚砷酸盐上观察到快速生长（μ = 0.359 h⁻¹），这涉及不同的非生物和生物氧化还原相互作用。最初的主导过程是一硫代亚砷酸盐非生物转化为砷酸盐和元素硫，随后是硫被微生物氧化为硫酸盐。嗜热栖热放线菌稳定生长期间微生物活性升高，可能是由于硫代硫酸盐和亚砷酸盐的微生物氧化，它们也是一硫代亚砷酸盐非生物转化的产物。然而，观察到的一硫代亚砷酸盐的快速减少，超过了与其产物平衡时的浓度，这也表明砷键合的S(-II)直接被微生物氧化为硫酸盐。游离硫化物非生物氧化太快，无法作为嗜热栖热放线菌的电子供体发挥作用。我们目前的实验室研究和之前的野外研究表明，在砷硫化物环境中，（超）嗜热菌可以间接或直接利用硫代亚砷酸盐。
