Carlström Charlotte I, Loutey Dana E, Wang Ouwei, Engelbrektson Anna, Clark Iain, Lucas Lauren N, Somasekhar Pranav Y, Coates John D
Department of Plant and Microbial Biology, University of California, Berkeley, California, USA.
Department of Civil and Environmental Engineering, University of California, Berkeley, California, USA.
Appl Environ Microbiol. 2015 Apr;81(8):2717-26. doi: 10.1128/AEM.03606-14. Epub 2015 Feb 6.
Two (per)chlorate-reducing bacteria, strains CUZ and NSS, were isolated from marine sediments in Berkeley and San Diego, CA, respectively. Strain CUZ respired both perchlorate and chlorate [collectively designated (per)chlorate], while strain NSS respired only chlorate. Phylogenetic analysis classified both strains as close relatives of the gammaproteobacterium Sedimenticola selenatireducens. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) preparations showed the presence of rod-shaped, motile cells containing one polar flagellum. Optimum growth for strain CUZ was observed at 25 to 30 °C, pH 7, and 4% NaCl, while strain NSS grew optimally at 37 to 42 °C, pH 7.5 to 8, and 1.5 to 2.5% NaCl. Both strains oxidized hydrogen, sulfide, various organic acids, and aromatics, such as benzoate and phenylacetate, as electron donors coupled to oxygen, nitrate, and (per)chlorate or chlorate as electron acceptors. The draft genome of strain CUZ carried the requisite (per)chlorate reduction island (PRI) for (per)chlorate respiration, while that of strain NSS carried the composite chlorate reduction transposon responsible for chlorate metabolism. The PRI of strain CUZ encoded a perchlorate reductase (Pcr), which reduced both perchlorate and chlorate, while the genome of strain NSS included a gene for a distinct chlorate reductase (Clr) that reduced only chlorate. When both (per)chlorate and nitrate were present, (per)chlorate was preferentially utilized if the inoculum was pregrown on (per)chlorate. Historically, (per)chlorate-reducing bacteria (PRB) and chlorate-reducing bacteria (CRB) have been isolated primarily from freshwater, mesophilic environments. This study describes the isolation and characterization of two highly related marine halophiles, one a PRB and the other a CRB, and thus broadens the known phylogenetic and physiological diversity of these unusual metabolisms.
从加利福尼亚州伯克利和圣地亚哥的海洋沉积物中分别分离出两株（高）氯酸盐还原菌，即CUZ菌株和NSS菌株。CUZ菌株能利用高氯酸盐和氯酸盐进行呼吸作用（统称为（高）氯酸盐），而NSS菌株仅能利用氯酸盐进行呼吸作用。系统发育分析将这两株菌归类为γ-变形菌硒酸盐还原沉积杆菌（Sedimenticola selenatireducens）的近亲。透射电子显微镜（TEM）和扫描电子显微镜（SEM）观察结果显示，细胞呈杆状，具运动性，有一根极生鞭毛。CUZ菌株在25至30°C、pH值为7、NaCl浓度为4%的条件下生长最佳，而NSS菌株在37至42°C、pH值为7.5至8、NaCl浓度为1.5至2.5%的条件下生长最佳。两株菌均能氧化氢气、硫化物、各种有机酸以及芳香族化合物（如苯甲酸盐和苯乙酸盐）作为电子供体，以氧气、硝酸盐和（高）氯酸盐或氯酸盐作为电子受体。CUZ菌株的基因组草图含有进行（高）氯酸盐呼吸作用所需的（高）氯酸盐还原岛（PRI），而NSS菌株的基因组含有负责氯酸盐代谢的复合氯酸盐还原转座子。CUZ菌株的PRI编码一种高氯酸盐还原酶（Pcr），该酶能还原高氯酸盐和氯酸盐，而NSS菌株的基因组包含一个仅能还原氯酸盐的独特氯酸盐还原酶（Clr）基因。当同时存在（高）氯酸盐和硝酸盐时，如果接种物预先在（高）氯酸盐上培养，则优先利用（高）氯酸盐。以往，（高）氯酸盐还原菌（PRB）和氯酸盐还原菌（CRB）主要是从淡水、嗜温环境中分离得到的。本研究描述了两株高度相关的海洋嗜盐菌的分离与特性，一株是PRB，另一株是CRB，从而拓宽了这些特殊代谢类型已知的系统发育和生理多样性。
