New transducing phage with RNA polymerase beta- and beta'-subunit genes derived from a hybrid phage lambda att80: isolation, genetic analysis and physical mapping]

A hybrid lambda att 80 phage with the genetic structure lambda (A-J) phi 80 (att-int-xis) imm lambda..cI857s7 is shown to be a convenient vector for creating transducing phages. On the one hand, the restriction analysis indicates that it has 3 restriction sites for EcoRI in comparison with 5 and 9 sites for parental phages lambda and phi 80 respectively. On the other hand, its buoyant density is less than that of phage lambda and under centrifugation it is easier separated from the phage transducing particles. When lambda att 80 prophage was excluded from the bfe locus of Escherichia coli, transducing phages with genes of two RNA polymerase beta-subunits (rpoB and rpoC) were isolated. To identify the latter, a convenient genetic test was worked out. A physical map of lambda att 80 drifd 35 transducing phage, carrying rpoB and rpoC genes has been constructed using endonucleases EcoRI and HindIII. A comparison of this map and the corresponding maps of transducing phages lambda drifd 18 and lambda drifd 47, studied earlier, led to the discovery of two integration sites of phage lambda within the locus bfe spaced apart by about 1800 nucleotide pairs. At all the sites both phages (lambda and lambda att 80) have integrated in the locus bfe in the counter clockwise order.     

The effect of various methods of preserving the fungus Aspergillus niger v. Tighem on its aggressive properties

Using the differential-thermic and thermogravimetric methods has shown that the most promising way of fungus Aspergillus niger storing when its aggressive properties against polyamid aren't lost is to keep the culture on polymeric matter (polyamid) and in soil.     

Photosynthetic activity and components of the electron transport chain in the aerobic bacteriochlorophyll <Emphasis Type="Italic">a</Emphasis>-containing bacterium <Emphasis Type="Italic">Roseinatronobacter thiooxidans</Emphasis>

Bioenergetics of the aerobic bacteriochlorophyll a-containing (BCl a) bacterium (ABC bacterium) Roseinatronobacter thiooxidans is a combination of photosynthesis, oxygen respiration, and oxidation of sulfur compounds under alkaliphilic conditions. The photosynthetic activity of Rna. thiooxidans cells was established by the photoinhibition of cell respiration and reversible photobleaching discoloration of the BCl a of reaction centers (RC), connected by the chain of electron transfer with cytochrome c ₅₅₁ oxidation. The species under study, like many purple bacteria and some of the known ABC bacteria, possesses a light-harvesting pigment-protein (LHI) complex with the average number of 30 molecules of antenna BCl a per one photosynthetic RC. Under microaerobic growth conditions, the cells contained bc ₁ complex and two terminal oxidases: cbb ₃-cytochrome oxidase and the alternative cytochrome oxidase of the a ₃ type. Besides, Rna. thiooxidans was shown to have several different soluble low- and high-potential cytochromes c, probably associated with the ability of utilizing sulfur compounds as additional electron donors.     

Microbial processes of the carbon and sulfur cycles in an ice‐covered,iron‐rich meromictic lake Svetloe (Arkhangelsk region,Russia)

Biogeochemical, isotope geochemical and microbiological investigation of Lake Svetloe (White Sea basin), a meromictic freshwater was carried out in April 2014, when ice thickness was ～0.5 m, and the ice‐covered water column contained oxygen to 23 m depth. Below, the anoxic water column contained ferrous iron (up to 240 μμM), manganese (60 μM), sulfide (up to 2 μM) and dissolved methane (960 μM). The highest abundance of microbial cells revealed by epifluorescence microscopy was found in the chemocline (redox zone) at 23–24.5 m. Oxygenic photosynthesis exhibited two peaks: the major one (0.43 μmol C L^?1 day^?1) below the ice and the minor one in the chemocline zone, where cyanobacteria related to Synechococcus rubescens were detected. The maximum of anoxygenic photosynthesis (0.69 μmol C L^?1 day^?1) at the oxic/anoxic interface, for which green sulfur bacteria Chlorobium phaeoclathratiforme were probably responsible, exceeded the value for oxygenic photosynthesis. Bacterial sulfate reduction peaked (1.5 μmol S L^?1 day^?1) below the chemocline zone. The rates of methane oxidation were as high as 1.8 μmol CH₄ L^?1 day^?1 at the oxi/anoxic interface and much lower in the oxic zone. Small phycoerythrin‐containing Synechococcus‐related cyanobacteria were probably involved in accumulation of metal oxides in the redox zone.     

Application of ribulose-1,5-bisphosphate carboxylase/oxygenase genes as molecular markers for assessment of the diversity of autotrophic microbial communities inhabiting the upper sediment horizons of the saline and soda lakes of the Kulunda Steppe

The genes encoding the key metabolic reactions are often used as functional markers for phylogenetic analysis and microbial ecology studies. The composition and structure of the genes encoding ribulose-1,5-bisphosphate carboxylase (RuBisCO) of various photoautotrophic bacteria, representatives of the order Chromatiales, including collection strains and the strains isolated from saline and soda lakes, were studied in detail. The green-like form I RuBisCO was detected in the majority of the studied strains. In some strains, the genes encoding both form I and form II RuBisCO were present, which has not been previously known for the representatives of this group of bacteria. Moreover, RuBisCO genes were used as functional markers to investigate the autotrophic microbial community inhabiting the upper horizons of bottom sediments of two saline soda lakes and two hypersaline neutral lakes of the Kulunda Steppe. In general, the diversity of autotrophic bacteria in the studied sediment horizons was low. In soda lakes, haloalkaliphilic cyanobacteria and sulfuroxidizing bacteria (SOB) of the genus Halorhodospira were predominant. In saline lakes, halophilic chemoautotrophic SOB Halothiobacillus and Thioalkalivibrio were found, as well as photoautotrophic bacteria of the genus Ectothiorhodosinus and cyanobacteria. Many phylotypes remained unidentified, which indicates the presence of groups of microorganisms with an unknown type of metabolism.     

Intercontinental spread of promiscuous mercury-resistance transposons in environmental bacteria

We demonstrate that horizontal spread of mer operons similar to worldwide spread of antibiotic-resistance genes in medically important bacteria occurred in bacteria found in ores, soils and waters. The spread was mediated by different transposons and plasmids. Some of the spreading transposons were damaged in different ways but this did not prevent their further spread. Certain transposons are mosaics composed of segments belonging to distinct sequence types. These mosaics arose as a result of homologous and site-specific recombination. Our data suggest that the mercury-resistance operons of Gram-negative environmental bacteria can be considered as a worldwide population composed of a relatively small number of distinct recombining clones shared, at least partially, by environmental and clinical bacteria.     

Seasonal Variations in the Structure of an Anoxygenic Phototrophic Bacterial Community from the Meromictic Lake Trekhtsvetnoe (Kandalaksha Bay,White Sea)

Microbiology - The community of anoxygenic phototrophic bacteria (APB) from the water column of the meromictic Lake Trekhtsvetnoe (Kandalaksha Bay, White Sea, Russia) was studied in March 2012 and...     

Biological activity of soils in the settlements of southern (Microtus rossiaemeridionalis) and bank (Clethrionomys glareolus) voles

The effect of southern (Microtus rossiaemeridionalis) and bank (Clethrionomys glareolus) voles on the biological activity of soddy-podzolic soil and agrozem has been studied. To estimate this effect, the activity of nitrogen and carbon transformation in the soil taken from the paths and different chambers of the holes of these rodents, as well as from the control plots where there were no voles, has been determined. The contents of organic carbon and nitrogen in the soil have been found. The parameters of functional diversity of the microbial community of soil have been studied. It has been noted that the effect of voles on the biological activity of the above soils manifested itself in increased intensity of aerobic and anaerobic destruction of organic matter and changes in the parameters of functional diversity of the microbial community of soils.     

Successional Changes in the Microbial Community of the Alkaline Lake Khilganta during the Dry Season

Microbial processes in a shallow, saline, alkaline Lake Khilganta (Southern Siberia) were studied during the dry season. During the drought, a crust was formed on the lake surface, where low rates of production processes were observed, with predominance of anoxygenic photosynthesis at 2.3 mg C/(dm³ day). The rates of microbial processes increased after short-term rains. During this period, a thin cyanobacterial mat was formed on the bottom, in which filamentous cyanbacteria Geitlerinema spp. predominated and the rate of oxygenic photosynthesis was up to 18 mg C/(dm³ day). Subsequent water evaporation and salinity increase resulted in altered community types and their activity. Red spots emerged on the mat surface, where anoxygenic prototrophic members of the genus Ectothiorhodospira predominated. Anoxygenic photosynthesis became the main production process in microbial mats, with the rate of 60 mg C/(dm³ day). At salinity increase to 200 g/L, the water remained in small depressions on the bottom, where extremophilic green algae Dunaliella sp. predominated, and the rate of oxygenic photosynthesis was 0.877 mg C/(dm³ day). These changes in the type and activity of microbial communities is an example of succession of microbial communities in Southern Siberia saline lakes during drought.