Hoeft McCann Shelley, Boren Alison, Hernandez-Maldonado Jaime, Stoneburner Brendon, Saltikov Chad W, Stolz John F, Oremland Ronald S
U.S. Geological Survey, Menlo Park, CA 94025, USA.
Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, CA 95064, USA.
Life (Basel). 2016 Dec 26;7(1):1. doi: 10.3390/life7010001.
Three novel strains of photosynthetic bacteria from the family Ectothiorhodospiraceae were isolated from soda lakes of the Great Basin Desert, USA by employing arsenite (As(III)) as the sole electron donor in the enrichment/isolation process. Strain PHS-1 was previously isolated from a hot spring in Mono Lake, while strain MLW-1 was obtained from Mono Lake sediment, and strain BSL-9 was isolated from Big Soda Lake. Strains PHS-1, MLW-1, and BSL-9 were all capable of As(III)-dependent growth via anoxygenic photosynthesis and contained homologs of arxA, but displayed different phenotypes. Comparisons were made with three related species: DSM 2111, DSM 243, and DSM 244. All three type cultures oxidized arsenite to arsenate but did not grow with As(III) as the sole electron donor. DNA-DNA hybridization indicated that strain PHS-1 belongs to the same species as DSM 2111 (81.1% sequence similarity), distinct from DSM 243 (58.1% sequence similarity). These results suggest that the capacity for light-driven As(III) oxidation is a common phenomenon among purple photosynthetic bacteria in soda lakes. However, the use of As(III) as a sole electron donor to sustain growth via anoxygenic photosynthesis is confined to novel isolates that were screened for by this selective cultivation criterion.
通过在富集/分离过程中使用亚砷酸盐（As(III)）作为唯一电子供体，从美国大盆地沙漠的苏打湖中分离出了三株新的外硫红螺菌科光合细菌。菌株PHS-1先前从莫诺湖的温泉中分离得到，菌株MLW-1从莫诺湖沉积物中获得，菌株BSL-9从大苏打湖分离得到。菌株PHS-1、MLW-1和BSL-9都能够通过无氧光合作用进行依赖As(III)的生长，并且含有arxA的同源物，但表现出不同的表型。与三个相关物种DSM 2111、DSM 243和DSM 244进行了比较。所有这三种模式菌株都能将亚砷酸盐氧化为砷酸盐，但不能以As(III)作为唯一电子供体生长。DNA-DNA杂交表明，菌株PHS-1与DSM 2111属于同一物种（序列相似性为81.1%），与DSM 243不同（序列相似性为58.1%）。这些结果表明，光驱动As(III)氧化的能力在苏打湖中的紫色光合细菌中是一种常见现象。然而，使用As(III)作为唯一电子供体通过无氧光合作用维持生长仅限于通过这种选择性培养标准筛选出的新分离株。
