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The article discusses the comparative analysis of chitinase diversity in the bottom sediments of the Baltic Sea which revealed that the variable region between the two conservative regions of the ?hiA gene cannot be used as a phylogenetic marker.

Microbiological, biogeochemical, and isotope geochemical investigations of the upper sediments of the Vistula and Curonian lagoons, Baltic Sea, were carried out. High content of organic matter in the sediments was responsible for the high numbers (over 10 cells cm) and activity of heterotrophic microorganisms. The calculated integral rates of dark CO assimilation for the upper 30 cm of the sediments varied 12.5 to 38.8 mmol m day and were somewhat higher in the Curonian Lagoon than in the Vistula Lagoon. Integral rates of sulfate reduction were higher in the more saline Vistula Lagoon. Rapid consumption of sulfates of the pore water resulted in intensified methanogenesis, with significantly higher rates detected in the silts of the Curonian Lagoon. High rates of methanogenesis in the Curonian Lagoon correlated with higher methane levels in its upper sediments and near-bottom water. The highest rates of methane oxidation were detected in the uppermost sediment horizons (oxidized or slightly reduced), which was an indication of the barrier role of aerobic methanotrophic bacteria. The calculated methane flows from the sediments into the water column were 0.45 and 0.007 mmol m day for the Vistula and Curonian Lagoons, respectively. Low methane flow from the sediments of the Curonian Lagoon resulted probably from the specific weather (wind) conditions during sampling. The near-stormy conditions in the Curonian Lagoon caused sediment detachment, resulting in methane release into the water column. [ABSTRACT FROM AUTHOR]

The numbers, biomass, and production of bacterioplankton were determined in the Russian Sector of the Gdansk Basin (Baltic Sea) in 2007-2009. Significant spatial and temporal variations were determined. During the year, bacterial activity increased with increasing water temperature and higher availability of organic substrates. The lowest bacterial production (0.01-31.63 mg C m day) was observed in late winter and late autumn, while the highest (0.17-341.70 mg C m day) occurred in spring and summer. Since bacterial numbers and biomass were found to depend on the weather conditions and the terrigenous inflow, significant variations were observed from year to year. The highest and lowest numbers and biomass of bacterioplankton determined in summer were 0.09-1.10 × 10 cells mL and 2-22 mg C m for July 2007 and 1.96-11.23 × 10 cells mL and 23-123 mg C m for July 2009. The values of these parameters were the highest along the coast and decreased towards the open sea. [ABSTRACT FROM AUTHOR]

Methane content and the rates of microbial processes of the carbon and sulfur cycles were determined for the sediments of the Vyborg Bay, Baltic Sea. Formation of the gas-bearing surface sediments in the Vyborg Bay was found to depend on the activity of the modern microbial processes of the transformation of organic matter, resulting in production of significant amounts of reduced gases (methane and hydrogen sulfide). Rapid consumption of sulfate in the course of sulfate reduction coupled to organic matter decomposition both suppressed anaerobic oxidation of methane and promoted microbial methanogenesis. The gasbearing sediments of this area therefore become a source of methane, and methane concentration in the near-bottom water increases significantly. [ABSTRACT FROM AUTHOR]

The microbial community of reduced pockmark sediments in the Russian sector of the Gdansk Deep, Baltic Sea, was investigated by molecular biological techniques. Fluorescent in situ hybridization was used to determine the numbers of eubacteria, archaea, and sulfate-reducing bacteria. Eubacteria were found to predominate in the upper 10 cm of the sediment (up to 5.3 × 10 cells/g wet sediment), while the number of archaea increased in the 10- to 30-cm layers (up to 2.8 × 10 cells/g wet sediment, which is higher than the number of eubacteria in the same horizons). Analysis of 16S rRNA gene fragments revealed members of the following phyla: Proteobacteria, Chloroflexi, Firmicutes, Planctomycetales, and high-G + C gram-positive bacteria. Sulfate-reducing bacteria (SRBs) of the families Syntrophaceae, Desulfuromonadaceae, and Actinobacteria of the genera Kocuria and Rothia were the predominant groups. Molecular probes were used to determine predominance of Desulfovibrionales in the SRB enrichment cultures obtained from different horizons of pockmark sediments. Three archaeal phylotypes were revealed, belonging to Euryarchaeota. One of these fell into the group of uncultured methanotrophic archaea (ANME-1a), while the other two were most closely related to uncultured methanogens. [ABSTRACT FROM AUTHOR]

The article offers information on the use of the enzyme Methyl-coenzyme M reductase (MCR) in methanotrophy. It states that there are plenty of methane craters in the Baltic Sea which contain large concentrations of methane, gas-saturated sediments and high levels of Anaerobic methane oxidation (AMO). Furthermore, it mentions that within these craters, gene sequence analysis was done on the MCR α subunit (mcrA) to detect the presence of methanotrophic archaea.