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首页> 外文期刊>Applied Microbiology >Coupled Arsenotrophy in a Hot Spring Photosynthetic Biofilm at Mono Lake, California
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Coupled Arsenotrophy in a Hot Spring Photosynthetic Biofilm at Mono Lake, California

机译：加利福尼亚莫诺湖温泉光合作用生物膜中的砷化肥耦合

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Red-pigmented biofilms grow on rock and cobble surfaces present in anoxic hot springs located on Paoha Island in Mono Lake. The bacterial community was dominated (～ 85% of 16S rRNA gene clones) by sequences from the photosynthetic Ectothiorhodospira genus. Scraped biofilm materials incubated under anoxic conditions rapidly oxidized As(III) to As(V) in the light via anoxygenic photosynthesis but could also readily reduce As(V) to As(III) in the dark at comparable rates. Back-labeling experiments with ~(73)As(V) demonstrated that reduction to ~(73)As(III) also occurred in the light, thereby illustrating the cooccurrence of these two anaerobic processes as an example of closely coupled arsenotrophy. Oxic biofilms also oxidized As(III) to As(V). Biofilms incubated with [~(14)C]acetate oxidized the radiolabel to ~(14)CO_(2) in the light but not the dark, indicating a capacity for photoheterotrophy but not chemoheterotrophy. Anoxic, dark-incubated samples demonstrated As(V) reduction linked to additions of hydrogen or sulfide but not acetate. Chemoautotrophy linked to As(V) as measured by dark fixation of [~(14)C]bicarbonate into cell material was stimulated by either H_(2) or HS~(?). Functional genes for the arsenate respiratory reductase ( arrA ) and arsenic resistance ( arsB ) were detected in sequenced amplicons of extracted DNA, with about half of the arrA sequences closely related (～98% translated amino acid identity) to those from the family Ectothiorhodospiraceae . Surprisingly, no authentic PCR products for arsenite oxidase ( aoxB ) were obtained, despite observing aerobic arsenite oxidation activity. Collectively, these results demonstrate close linkages of these arsenic redox processes occurring within these biofilms.
机译：在Mono湖Paoha岛上的缺氧温泉中，岩石和卵石表面上生长着红色色素生物膜。细菌群落以光合作用硫代杆状螺旋藻属的序列为主（约占16S rRNA基因克隆的85％）。在缺氧条件下孵育的废弃生物膜材料在光下通过产氧光合作用迅速将As（III）氧化为As（V），但也可以在黑暗中以可比速率将As（III）轻松还原为As（III）。用〜（73）As（V）进行的反标记实验表明，在光下也发生了〜（73）As（III）的还原，从而说明了这两个厌氧过程的同时发生，作为紧密耦合的雄性营养不良的一个例子。氧化生物膜还将As（III）氧化为As（V）。与[〜（14）C]乙酸盐一起孵育的生物膜在明亮但不是黑暗的条件下将放射性标记氧化为〜（14）CO_（2），表明其具有光异养性而不是化学异养性。缺氧，黑暗培养的样品表明，As（V）的减少与添加氢或硫化物而不是乙酸盐有关。通过H_（2）或HS〜（α）刺激通过[〜（14）C]碳酸氢盐暗固定到细胞材料中而与As（V）相关的化学自养。在提取的DNA的测序扩增子中检测到了砷酸呼吸还原酶（arrA）和砷抗性（arsB）的功能基因，其中大约有一半的arrA序列与Ectothiorhodospiraceae家族的基因紧密相关（约98％的翻译氨基酸同一性）。令人惊讶的是，尽管观察到好氧亚砷酸盐的氧化活性，但仍未获得用于亚砷酸盐氧化酶（aoxB）的真实PCR产物。总的来说，这些结果证明了在这些生物膜内发生的这些砷氧化还原过程的紧密联系。

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