[Modeling the Propagation of Microbial Cells and Phage Particles from the Sites of Permafrost Thawing.]

A method is proposed for integral assessment of the propagation of microbial cells and viral parti- cles during seasonal thawing of relic ice wedge layers. The results of on-site and laboratory investigation car- ried out in the upper part of permafrost exposure at Mamontova Gora (Yakutiya, Russia) are presented. To increase reliability of the results, suspensions of two microbial species and two coliphage species were intro- duced as biomarkers directly on the surface of thaing ice and in the meltwater flow. Each of the four different model biological objects was shown to possess unique parameters of movement in the meltwater flow and is able to move 132 m in 25-35 min with the water flow.

[Prokaryotic community of subglacial bottom sediments of Antarctic Lake Untersee: detection by cultural and direct microscopic techniques].

The heterotrophic mesophilic component was studied in microbial communities of the samples of frozen regolith collected from the glacier near Lake Untersee collected in 2011 during the joint Russian-American expedition to central Dronning Maud Land (Eastern Antarctica). Cultural techniques revealed high bacterial numbers in the samples. For enumeration of viable cells, the most probable numbers (MPN) method proved more efficient than plating on agar media. Fluorescent in situ hybridization with the relevant oligonucleotide probes revealed members of the groups Eubacteria (Actinobacteria, Firmicutes) and Archaea. Application of the methods of cell resuscitation, such as the use of diluted media and prevention of oxidative stress, did not result in a significant increase in the numbers of viable cells retrieved form subglacial sediment samples. Our previous investigations demonstrated the necessity for special procedures for efficient reactivation of the cells from microbial communities of preserved fossil soil and permafrost samples collected in the Arctic zone. The differences in response to the special resuscitation procedures may reflect the differences in the physiological and morphological state of bacterial cells in microbial communities subject to continuous or periodic low temperatures and dehydration.

[Diversity of bacterial forms in ice wedge of the Mamontova Gora Glacial complex (central Yakutiya)].

Electron microscopic investigation of four samples of ancient ice wedge from the Pleistocene glacial complex of Mamontova Gora (Yakutiya, Russia) revealed high diversity of bacteriomorphic particles. Their structural features included the presence of electron-transparent zones, presumably inclusions containing storage compounds, and microenvironment (capsules or external sheaths). These features may be a result of adaptive strategies providing for microbial survival under permafrost conditions. Predominance of rod-shaped forms morphologically resembling coryneform actinobacteria was found. X-ray microanalysis revealed organic origin of bacteriomorphic particles. Some particles were characterized by incomplete spectra of the major biogenic elements, resulting probably from low-temperature damage to the cellular structures. Total numbers of aerobic heterotrophic bacteria determined by plating on nutrient media were comparable to the values obtained for permafrost soils and Arctic ice. Predominance of coryneform actinobacteria was observed. Abundance of these evolutionarily early groups of actinobacteria may indicate the ancient origin of the microflora of the relic frozen rocks.

[Dormant state and phenotypic variability of Staphylococcus aureus and Corynebacterium pseudodiphtheriticum].

Ability to produce dormant forms (DF) was demonstrated for non-spore-forming bacteria Staphylococcus aureus (a nonpathogenic strain) and Corynebacterium pseudodiphtheriticum (an organism of the normal oropharyngeal flora). The salient features of the sthaphylococcal and corynebacterial DF were (1) prolonged preservation of viability; (2) resistance to damaging factors (heat treatment); and (3) specific morplology and ultrastructure. The optimal conditions for DF formation were (1) transfer of the stationary-phase cultures into saline solution with CaCl2 (10-300 mM) (for S. aureus); (2) growth in SR1 synthetic medium with fivefold nitrogen limitation (for C. pseudodiphtheriticum); and (3) incubation with (1-5) x 10(-4) M) of C12-AHB, an alkylhydroxybenzene akin to microbial anabiosis autoinducers. Increase of C12-AHB concentration to 7 x 10(-4) -2 x 10(-3) M resulted in "mummification" with irreversible loss of viability without autolytic processes. Germination of the dormant forms was followed by increased phenotypic variability, as seen from (1) diversity of colony types and (2) emergence of antibiotic-resistant clones on selective media. The share of kanamycin-resistant S. aureus variants was most numerous 0.002-0.01% in 4-month DF suspensions in saline with CaCl2. In the C. pseudodiphtheriticum DF produced under the effect of C12-AHB, the share of kanamycin-resistant variants was also found to increase. These data point to association between emergence of antibiotic-resistant variants and their persistence in dormant state mediated by starvation stress and regulated by AHB.

[Changes in the phase variant spectra in the populations of lactic acid bacteria under antibiotic treatment].

Effect of the antibiotics kanamycin and ampicillin on growth and phase variation of the populations of four strains of lactic acid bacteria (Lactobacillus sp. M67AT, L. casei MB, Enterococcus faecium M, and E. faecium M3185) was studied. The presence of antibiotics in the medium resulted in a dose-dependent decrease in viable cell numbers and in partial or complete substitution of the dominant S variant with the minor Sm and Sb variants. The variants differed in colony morphology, as well as in some physiological, biochemical, biotechnological, and probiotic characteristics. The Sm type variants of all strains exhibited the highest resistance to antibiotics. High production of exopolysaccharides was found in Sb variants of lactobacilli and in S variants of enterococci. The highest antibacterial activity was found in Sm variants of lactobacilli, especially in Lactobacillus sp. M76AT The latter is biotechnologically the most promising strain, since all variants fermented milk yielding the products with uniformly pronounced functional and organoleptic properties. These patterns are of importance for the understanding of the mechanisms of antibiotic resistance and for selection of the variants with desired properties, as well as for quality control of the lactic acid bacteria starter cultures.

[Dominant phylotypes in the 16S rRNA gene clone libraries from bacterial mats of the Uzon caldera (Kamchatka, Russia) hydrothermal springs].

In situ analysis of the 16S rRNA genes form bacterial mats of five hydrothermal springs (36-58 degrees C) in the Uzon caldera (Kamchatka, Russia) was carried out using clone libraries. Eight clone libraries contained 18 dominant phylotypes (over 4-5%). In most clone libraries, the phylotype of the green sulfur bacterium Chlorobaculum sp. was among the dominant ones. The phylotypes of the green nonsulfur bacteria Chloroflexus and Roseiflexus and of purple nonsulfur bacteria Rhodoblastus, Rhodopseudomonas, and Rhodoferax were also among the dominant ones. Cyanobacteria were represented by one dominant phylotype in a single spring. Among nonphototrophic bacteria, the dominant phylotypes belonged to Sulfyrihydrogenibium sp., Geothrixsp., Acidobacterium sp., Meiothermus sp., Thiomonas sp., Thiofaba sp., and Spirochaeta sp. Three phylotypes were not identified at the genus level. Most genera of phototrophic and nonphototrophic organisms corresponding to the phylotypes from Uzon hydrotherms have been previously revealed in the hydrotherms of volcanically active regions of America, Asia, and Europe. These results indicate predominance of bacterial mats carrying out anaerobic photosynthesis in the hydrotherms of the Uzon caldera.

[Antimicrobic features of phenolic lipids].

The connection between the efficiency of phenolic lipids (PL) and their hydrophobic property (solubility) and hydrophobic property of microorganisms' cell structure is shown. The mixture of amphiphilic di(oxiphenil)-phenil-methanes, which act bacteriostatically under 15 mg/l, possesses maximal efficiency against Staphylococcus aureus. Against Mycobacterium smegmatis with hydrophobic cell wall, hydrophobic 2,4-dialkylocibenzol 70 mg/l was the most effective. Hexylresorcin (HR) stops the development of gram-positive bacteria in concentrations 20-50 mg/l, that of gram-negative bacteria in concentration 65 mg/l, that of M. smegmatis at 70 mg/l, and that of yeast and fungi at 300 mg/l. HR prevails bacteria spores germination in the concentration 25-100 mg/l. The dependence of antibacterial action of isomers and homologues of alkylresorcins on their structure--number, position, and length of alkyl substituents--is studied.

[Structural organization of the phospholipid constituent of cell membranes from Streptomyces hygroscopicus, as determined from neutron diffraction data].

The nanoparameters of the membrane from actinobacteria have been determined by the method of neutron diffraction on multilamellar lipid membranes. It was found that the repeat distance of a partly hydrated membrane formed from the phosphohpid fraction of Streptomyces hygroscopicus (S. hygroscopicus) is 85.8 +/- 0.5 A at T = 20 degrees C and decreases to 83.5 +/- 0.5 A at T = 40 degrees C. Some lipids are not incorporated into the bilayer and form the liquid micellar phase with micelles of size 54.2 +/- 0.2 A.