[Thirty-five years of the Department of Biology of Gas-oxidizing Microorganisms of the D.K. Zabolotnyi Institute of Microbiology and Virology of the Academy of Sciences of Ukraine]. / Otdelu biologii gazookisliaiushchikh mikroorganizmov Instituta mikrobiologii i virusologii im. D.K. Zabolotnogo NAN Ukrainy--35 let.

The basic trends of the department scientific activity are presented. The priority results of investigations of methaneoxidizing bacteria biology are given. The biothechnological development of the department (obtaining of products of microbial synthesis: protein, polysaccharides, antialcoholic and antinarcotic preparations) are considered in detail. Possible areas of their application are presented.

[Intensification of synthesis of the exopolysaccharide ethapolan by Acinetobacter sp. 12S grown on a mixture of substrates]. / Intensifikatsiia sinteza ékzopolisakharida étapolana na smesi rostovykh substratov.

Enhanced synthesis of the exopolysaccharide (EPS) ethapolan by Acinetobacter sp. 12S was observed when the bacterium was grown on a mixture of two energetically nonequivalent substrates (ethanol and glucose) taken in a molar proportion of 3.1:1. The efficiency of carbon transformation into EPSs was maximum when sodium ions were absent in the medium, the concentration of nitrogen source was reduced to 0.3-0.45 g/l, and the inoculum was grown on ethanol. Such conditions provided an increase in the maximum specific growth rate and its attainment in earlier cultivation terms. Molasses as a substitution for glucose was inefficient. The activities of the key enzymes of C2-metabolism in Acinetobacter sp. 12S cells grown on the substrate mixture was 1.1 to 1.7 times lower than they were during growth on ethanol alone. The activity of isocitrate lyase in cells grown on the substrate mixture declined to an even greater extent (by 4 to 7 times), indicating that the role of the glyoxylate cycle in such cells is insignificant.

[Ethanol formation by methane-utilizing bacteria at ethane co-metabolism]. / Obrazovanie étanola metanispol'zuiushchimi bakteriiami pri kometabolizme étana.

It was established, that EDTA (1.0 mM) and formamide (100 mM) are inhibitors of methanol dehydrogenase in Methylobacter luteus 12b, Methylomonas rubra 15sh and Methylococcus thermophilus 111p. The investigated strains co-metabolised ethane with the use of formate as the co-substrate. The application of formamide (or EDTA) as inhibitors of methanol dehydrogenase prevented from further transformation of ethanol and resulted in accumulation of extracellular ethanol. It was shown, that M. rubra 15sh accumulated extracellular ethanol under cultivation in a chemostate. The carried out researches have shown a regulation path of co-metabolism process of hydrocarbons by methane utilizing bacteria. Using the specific inhibitors of methanol dehydrogenase and a source of reducing agent (energy) for methane monooxygenase with the help of the cells of methane-oxidizing bacteria it is possible to obtain from ethane or other hydrocarbons the products of their monooxygenation--alcohols.

[Sensitivity of soil bacteria isolated from the alienated zone around the Chernobyl Nuclear Power Plant to various stress factors]. / Chuvstvitel'nost' k stressovym faktoram pochvennykh bakterii, izolirovannykh iz zony otchuzhdeniia Chernobyl'skoi AES.

Seventy strains of chemoorganotrophic bacteria isolated by our group in 1993-1994 from soil sampled in the zone around the Chernobyl Nuclear Power Plant (ChNPP) were studied with respect to their sensitivity to various stress factors damaging DNA. Bacillus subtilis, B. cereus (both spores and vegetative cells), Methylobacterium extorquens, M. mesophilicum, and unidentified pigmented bacteria were found to be the most resistant to ultraviolet (UV) radiation, exhibiting LD90 values of 40 to more than 211 J/m2. The same bacteria, as well as Bacillus polymyxa, were tolerant to hydrogen peroxide (lethal concentrations of H2O2 ranged from 0.3 to 1.0 M); i.e., UV-resistant strains were also tolerant to hydrogen peroxide and vice versa. Fluorescent pseudomonads were the most sensitive to both UV radiation and H2O2, showing LD90 from 6 to 18 J/m2 and a lethal concentration of H2O2 lower than 0.1 M. All of the soil samples collected in the alienated zone around the ChNPP, where the radioactivity of the soil had decreased from 1000 to 2 microCi/kg soil over the period from 1987 to 1995, contained not only resistant bacteria but also a small number of bacteria sensitive to UV radiation and H2O2.

[Ultraviolet irradiation of soil samples as a model of the effect of stress factors on bacterial diversity in soil ecosystem]. / Obluchenie pochvennykh obraztsov ul'trafioletom kak model' deistviia stressovykh faktorov na raznoobraziebakterii v pochvennykh ékosistem akh.

UV irradiation is proposed for use in studying the effect of radioactive irradiation, since radioresistant bacteria are, as a rule, resistant to UV, and the mechanisms of repair of cell damage induced by UV and ionizing radiation are similar. It was found that the total number of bacteria and the number of dominant species in soil samples exposed to UV radiation decreased, indicating the unfavorable effect of UV radiation on bacterial diversity in soil ecosystems. The percentage of cells of bacteria belonging to dominant species varied significantly depending on the intensity of UV irradiation. It can be inferred that long-term irradiation of soils must impair the stability of soil ecosystems, a phenomenon that was indeed observed in the zone around the Chernobyl Nuclear Power Plant. At the same time, the UV irradiation of soil samples made it possible to reveal minor species, primarily UV-resistant pigmented bacteria. UV irradiation can probably be used as a selective factor for the isolation of radioresistant species.