Department Microorganisms, Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany.
Department Bioinformatics, Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany.
Environ Microbiol. 2018 Jul;20(7):2438-2455. doi: 10.1111/1462-2920.14253. Epub 2018 Jul 26.
Anaerobic strains affiliated with a novel order-level lineage of the Phycisphaerae class were retrieved from the suboxic zone of a hypersaline cyanobacterial mat and anoxic sediments of solar salterns. Genome sequences of five isolates were obtained and compared with metagenome-assembled genomes representing related uncultured bacteria from various anoxic aquatic environments. Gene content surveys suggest a strictly fermentative saccharolytic metabolism for members of this lineage, which could be confirmed by the phenotypic characterization of isolates. Genetic analyses indicate that the retrieved isolates do not have a canonical origin of DNA replication, but initiate chromosome replication at alternative sites possibly leading to an accelerated evolution. Further potential factors driving evolution and speciation within this clade include genome reduction by metabolic specialization and rearrangements of the genome by mobile genetic elements, which have a high prevalence in strains from hypersaline sediments and mats. Based on genetic and phenotypic data a distinct group of strictly anaerobic heterotrophic planctomycetes within the Phycisphaerae class could be assigned to a novel order that is represented by the proposed genus Sedimentisphaera gen. nov. comprising two novel species, S. salicampi gen. nov., sp. nov. and S. cyanobacteriorum gen. nov., sp. nov.
从高盐蓝藻席和缺氧盐田沉积物的亚缺氧带中分离到了与 Phycisphaerae 纲的一个新型目级谱系相关的厌氧菌株。获得了五个分离株的基因组序列，并与来自各种缺氧水生环境的相关未培养细菌的宏基因组组装基因组进行了比较。基因含量调查表明，该谱系的成员具有严格的发酵糖解代谢，可以通过分离株的表型特征得到证实。遗传分析表明，所回收的分离株没有典型的 DNA 复制起点，但可能通过导致加速进化的替代位点启动染色体复制。该进化枝内进一步潜在的进化和物种形成驱动因素包括代谢特化导致的基因组缩减和通过移动遗传元件进行的基因组重排，这些在高盐沉积物和席中的菌株中普遍存在。基于遗传和表型数据，可将 Phycisphaerae 纲内严格厌氧异养浮霉菌的一个独特群体分配到一个新的目，该目由拟议的 Sedimentisphaera 属代表，包含两个新种，即 S. salicampi 属，sp. nov. 和 S. cyanobacteriorum 属，sp. nov.。
