[Electron microscopic detection and in situ characterization of bacterial nanoforms in extreme biotopes].

The morphology, ultrastructure, and quantity of bacterial nanoforms were studied in extreme biotopes: East Siberia permafrost soil (1-3 Ma old), petroleum-containing slimes (35 years old), and biofilms from subsurface oil pipelines. The morphology and ultrastructure of microbial cells in natural biotopes in situ were investigated by high-resolution transmission electron microscopy and various methods of sample preparation: ultrathin sectioning, cell replicas, and cryofractography. It was shown that the biotopes under study contained high numbers of bacterial nanoforms (29-43% of the total number of microorganisms) that could be assigned to ultramicrobacteria due to their size (diameter of < or =0.3 microm and volume of < or =0.014 microm3) and structural characteristics (the presence of the outer and cytoplasmic membranes, nucleoid, and cell wall, as well as their division patterns). Seven different morphostructural types of nanoforms of vegetative cells, as well as nanospores and cyst-like cells were described, potentially representing new species of ultramicrobacteria. In petroleum-containing slimes, a peculiar type of nanocells was discovered, gram-negative cells mostly 0.18-0.20 x 0.20-0.30 microm in size, forming spherical aggregates (microcolonies) of dividing cells in situ. The data obtained promoted the isolation of pure cultures of ultramicrobacteria from petroleum-containing slimes; they resembled the ultramicrobacterium observed in situ in their morphology and ultrastructure.

[Characterization of Vibrio cholerae eltor in the city of Kazan in 2001]. / Kharakteristika kholernykh vibrionov él'tor, vydelennykh v g. Kazan' v 2001 g.

Information on V. cholerae eltor isolated in the focus of cholera in Kazan in 2001 at different periods of the outbreak is presented. The identity of strains isolated from patients, vibriocarriers and environmental objects, including their antibioticograms (sensitivity to cyprofloxacin and resistance to trimethoprim--sulfamethoxazole, streptomycin, furazolidone and nalidixic acid, which may be regarded as markers), is shown. Variable tandem repetitions in the DNA of 30 isolates strains of different origin have been determined. The results of this determination make it possible to classify all these strains as one genotype, which confirms the suggestion on the circulation of one subclone of the infective agent of cholera in the focus. As revealed in this investigation, the isolated strains are labile with respect to diagnostic phage eltor, while ctx+ strains are resistant to phage eltor ctx+.

[Methanotrophic communities in the soils of Russian northern taiga and subarctic tundra]. / Metanotrofnye soobshchestva pochv severnoi taigi i subarkticheskoi tundry Rossii.

The PCR analysis of DNA extracted from soil samples taken in Russian northern taiga and subarctic tundra showed that the DNA extracts contain genes specific to methanotrophic bacteria, i.e., the mmoX gene encoding the conserved alpha-subunit of the hydroxylase component of soluble methane monooxygenase, the pmoA gene encoding the alpha-subunit of particulate methane monooxygenase, and the mxaF gene encoding the alpha-subunit of methanol dehydrogenase. PCR analysis with group-specific primers also showed that methanotrophic bacteria in the northern taiga and subarctic tundra soils are essentially represented by the type I genera Methylobacter, Methylomonas, Methylosphaera, and Methylomicrobium and that some soil samples contain type II methanotrophs close to members of the genera Methylosinus and Methylocystis. The electron microscopic examination of enrichment cultures obtained from the soil samples confirmed the presence of methanotrophic bacteria in the ecosystems studied and showed that the methanotrophs contain only small amounts of intracytoplasmic membranes.