title: [Comparative characteristics of free-living ultramicroscopical bacteria obtained from extremal biotopes].
abstract: We isolated 50 strains of free-living ultrasmall bacteria with a cell volume that varies from 0.02 to 1.3 microm3 from a range of extremal natural biotopes, namely permafrost soils, oil slime, soils, lake silt, thermal swamp moss, and the skin integuments of the clawed frog, Xenopus laevis. Of them, 15 isolates, characterized by a cell size of less than 0.1 microm3 and a genome size from 1.5 to 2.4 Mb, were subsumed to ultramicrobacteria belonging to different philogenetic groups (Alphaproteobacteria, Bacteroidetes, Actinobacteria) and genera (Kaistia, Chryseobacterium, Microbacterium, Leucobacter, Leifsonia, and Agrococcus) of the Bacteria domain. They are free-living mesophilic heterotrophic aerobic bacteria. The representatives of Kaistia and Chryseobacterium genera were capable of facultative parasitism on other species of chemo-organotrophic bacteria and cyanobacteria. The ultramicrobacteria differed in their morpholgy, cell ultrastructural organization, and physiological and biochemical features. According to the fine structure of their cell walls, the isolates were subdivided into two groups, namely Gram-positive and Gram-negative forms.
authors.forename: N E
authors.initials: NE
authors.lastname: Suzina
authors.forename: T Z
authors.initials: TZ
authors.lastname: Esikova
authors.forename: R R
authors.initials: RR
authors.lastname: Oleinikov
authors.forename: B
authors.initials: B
authors.lastname: Gafarov
authors.forename: A P
authors.initials: AP
authors.lastname: Shorokhov
authors.forename: V N
authors.initials: VN
authors.lastname: Polivtseva
authors.forename: D V
authors.initials: DV
authors.lastname: Ross
authors.forename: T N
authors.initials: TN
authors.lastname: Abashina
authors.forename: V I
authors.initials: VI
authors.lastname: Duda
authors.forename: A M
authors.initials: AM
authors.lastname: Boronin
mesh_terms: D000818:Animals; D001419:Bacteria / Q000235:genetics / Q000302:isolation & purification*; D018407:Bacterial Physiological Phenomena; D002473:Cell Wall / Q000648:ultrastructure; D045247:Chryseobacterium / Q000302:isolation & purification / Q000502:physiology; D059646:Genome Size; D016680:Genome, Bacterial; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S; D012426:Russia; D012988:Soil Microbiology; D053833:Wetlands; D014982:Xenopus laevis / Q000382:microbiology
chemical_list: D012336:RNA, Ribosomal, 16S