Springer Science and Business Media LLC

Methane oxidation rates and diversity of methane-oxidizing microorganisms in the Kara Sea upper sediments at the sites of conserved gas prospecting wells were investigated. Analysis of the 16S rRNA gene sequences revealed members of the class Gammaproteobacteria, order Methylococcales. All samples exhibited similar diversity of the methane filter microorganisms, comprising mainly of methanotrophs related to the genus Methyloprofundus and of uncultured methanotrophic bacteria detected previously in the upper sediments of the Arctic seas. Molecular identification of methane-oxidizing bacteria of this community by high-throughput sequencing of the pmoA gene encoding particulate methane monooxygenase confirmed the similar structure of the methane filter in the upper sediments impaired by drilling and at the reference sites at significant distance from the wells. The sediments at the conserved well drilled less than two years earlier were shown to have the characteristics of a methane seep, i.e., elevated level of dissolved methane and high rates of microbial methane oxidation. No indication of methane seepage was observed for the wells conserved more than two years earlier; abundance of methane-oxidizing bacteria in their vicinity was below the detection threshold.

Các khác biệt về thành phần định lượng và định tính của các nhóm vi sinh vật sinh lý và sinh hóa khác nhau được phát hiện trong biofilm hình thành trên các cơ sở đá ở khu vực cận bờ của Hồ Baikal phía Nam (tháng 8 năm 2012) tại các khu vực có mức tải trọng con người khác nhau. Sự phong phú tối đa của vi sinh vật được ghi nhận trong các biofilm epilithic từ khu vực Nhà máy Bột giấy và Giấy Baikalsk: vi sinh vật dinh dưỡng hữu cơ (770.2 ± 290.3 × 103 CFU/cm2); amylolytics (38.1 ± 7.7 × 103 CFU/cm2); vi sinh vật phân giải phosphate (4.8 ± 1.4 × 103 CFU/cm2); vi sinh vật di chuyển phosphate (212.0 ± 27.6 × 103 CFU/cm2); vi sinh vật oxy hóa phenol (15.7 ± 2.4 × 103 CFU/cm2); nấm mốc (3.2 ± 0.4 × 103 CFU/cm2); và tổng số vi khuẩn coliform (193.3 ± 28.2 CFU/cm2), với tổng số vi sinh vật (TMA tại 37°C) là 24.9 ± 1.7 × 103 CFU/cm2, cho thấy hoạt động phân hủy cao của các biofilm nhằm phản ứng với tải trọng nhân tạo trong khu vực. Các biofilm epilithic ở khu vực Bol’shie Koty thể hiện sự phong phú thấp nhất của vi sinh vật dinh dưỡng hữu cơ và vi sinh vật phân giải phosphate, trong khi nấm mốc không có mặt.

Azospirillum brasilense cells deprived of capsular exopolysaccharides completely lost their ability to bind wheat germ agglutinin (WGA) and much of their ability to attach to wheat seedling roots. The decapsulation of bacterial cells by washing them with a NaCl solution led to an increase in the relative hydrophobicity of the cell surface. The pretreatment of wheat seedling roots with N-acetyl-D-glucosamine (GlcNAc) or the GlcNAc-containing polysaccharide complexes stripped from Azospirillum cells reduced their attachment to the roots. Under the experimental conditions used (3-h incubation of wheat seedling roots with exponential-phase azospirilla), bacterial adsorption is mainly driven by the specific mechanisms attachment of the cells to the roots, whose operation is due to the capsular polysaccharide components and the WGA present on the wheat seedling roots.

Mycological investigation of the Japanese scallop Mizuhopecten yessoensis (Jay) (Bivalvia) from different areas of the Peter the Great Bay (Sea of Japan) was conducted. Isolates from internal organs of M. yessoensis scallop comprise 72 species of filamentous fungi from 30 genera of ascomycetes, anamorphic fungi, and zygomycetes. Species richness of filamentous fungi—fungi of the genera Aspergillus, Penicillium, Cladosporium, and Chaetomium—in the internal organs of bivalve mollusks increases in polluted coastal waters.

The magnitude of transmembrane potential Δψ in cells of Escherichia coli K12 was determined by the method of flow cytofluorometry for different phases of growth. It was large in the log phase, whereas in the lag and stationary phases, the population was shown to consist of two subpopulations with low and large values of Δψ in cells. In the presence of 200 mg/l of 2,4,6-trinitrotoluene (TNT), this bimodal distribution of Δψ over the population was observed during the entire growth period until TNT was almost completely eliminated from the cultivation medium (to a concentration of 18–20 mg/l). The mean value of Δψ in cells of the population grown in the presence of TNT was substantially smaller than that in controls due to the larger fraction of the subpopulation with a low value of Δψ. Upon elimination of TNT, the distribution of Δψ in cells of the culture became unimodal and close to that in the control culture in the early log phase of growth. These findings are discussed from the standpoint that considers heterogeneity of the culture of Escherichia coli K12 as a mechanism of its adaptation to the presence of xenobiotics.

Aerobic methylobacteria utilizing oxidized and substituted methane derivatives as carbon and energy sources are widespread in nature and involved in the global carbon cycle, being a unique biofilter on the path of these C1 compounds from different ecosystems to the atmosphere. New data on the biological features of moderately halophilic, neutrophilic, and alkaliphilic methylobacteria isolated from biotopes with higher osmolarity (seas, saline and soda lakes, saline soils, and deteriorating marble) are reviewed. Particular attention is paid to the latest advances in the study of the mechanisms of osmoadaptation of aerobic moderately haloalkaliphilic methylobacteria: formation of osmolytes, in particular, molecular and genetic aspects of biosynthesis of the universal bioprotectant ectoine. The prospects for further studies of the physiological and biochemical principles of haloalkalophily and for the application of haloalkaliphilic aerobic methylobacteria in biosynthesis and biodegradation are discussed.