[Effect of gas pressure on the physiological state of methylotropic bacteria].
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Gases↗
Biomedical subjects
Iu R Malashenko
Publications and source records attributed to Iu R Malashenko.
[Stability of genetic markers in methane-oxidizing bacteria].
A number of Methylococcus thermophilus 111p clones have been obtained which have acquired resistance to tetracycline. The stability of maintenance of marker resistance in these clones and also in already designed Methylomonas rubra 15sh mutants has been investigated. Chromosomal markers resistance to antibiotics or formaldehyde were maintained in the marked strains Methylococcus thermophilus 111p and Methylomonas rubra 15sh after storage in nonselective conditions. The markers of resistance to antibiotics, which were coded by plasmids (pAS8-121 and pULB113), were not always preserved in Methylomonas rubra and Methylococcus thermophilus. The stability of maintenance of chromosomal markers in the investigated methane oxidizing bacteria testifies to the fact that they can be used in laboratory and industrial practice for testing the marked bacteria on selective media. The collection of the marked bacteria-mutants Methylomonas rubra 15sh and Methylococcus thermophilus 111p has been created. These strains stably support the marker resistance to various antibiotics or formaldehyde in unselective conditions.
Anti-Bacterial Agents↗
[Alternativity of methane assimilation pathways in obligate methylotrophs].
The activity of key enzymes involved in the primary pathways of methane assimilation and enzymes of the citrate cycle was determined in various obligate methylotrophs: mesophilic, thermotolerant, and thermophilic. The bacteria are characterized by the membrane ultrastructure of the I type, high activity of hexosephosphate synthase, NAD- and NADP-specific isocitrate dehydrogenase, and the absence of alpha-ketoglutarate dehydrogenase. The bacteria also displayed the activity of key enzymes of the serine cycle, hydroxypyruvate reductase, and serineglyoxylate aminotransferase. Therefore, both the ribulose monophosphate and serine pathways are involved in methane assimilation, and the division of methanotrophs into two groups, according to their metabolism, is tentative.
Aldehyde-Lyases↗
[The effect of gamma-radiation and desiccation on the viability of the soil bacteria isolated from the alienated zone around the Chernobyl Nuclear Power Plant].
Methylobacterium extorquens, M. mesophilicum, and Bacillus subtilis strains were found to be resistant to gamma-radiation, irrespective of whether they were isolated from the alienated zone around the Chernobyl Nuclear Power Plant or outside this zone. The LD90 of Methylobacterium and B. subtilis strains with respect to gamma-radiation was 2.0-3.4 and 3.7-4.4 kGy, respectively, whereas their LD99.99 values were 4.5-6.9 and more than 10 kGy, respectively. The high threshold levels of gamma-radiation for Methylobacterium and B. subtilis imply the efficient functioning of DNA repair systems in these bacteria. Unlike Bacillus polymyxa cells, the cells of M. extorquens, M. mesophilicum, and B. subtilis were also resistant to desiccation. Pseudomonas sp., Nocardia sp., and nocardioform actinomycetes were sensitive to both gamma-radiation and desiccation. Similar results were obtained when the bacteria studied were exposed to hydrogen peroxide and ultraviolet radiation. The results obtained indicate that the bacteria that are resistant to gamma-radiation are also resistant to desiccation, UV radiation, and hydrogen peroxide. The possibility of using simple laboratory tests (such as the determination of bacterial resistance to UV light and desiccation) for the evaluation of bacterial resistance to gamma-radiation is discussed.
Bacillus↗
[Thirty-five years of the Department of Biology of Gas-oxidizing Microorganisms of the D.K. Zabolotnyĭ Institute of Microbiology and Virology of the Academy of Sciences of Ukraine].
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.
Academies and Institutes↗
[Actual problems of bacteria phylogenetic classification].
Historical aspects of development of phylogenetic bacteria taxonomy and essence of species in systematics of bacteria are considered. Comparative analysis of phenotypic and phylogenic classification of bacteria is conducted. Basic results of 16S rRNA gene sequence for bacteria are adduced. Comparative estimation of molecular biological methods in microbiologic researches and also estimation of potentialities and shortcomings of 16S rRNA gene sequence-analysis in systematics of bacteria are conducted.
Bacteria↗
[Soil drying as a model for the action of stress factors on the natural bacterial population].
The drying of soil samples reduced the abundance (especially of predominant species) and the diversity of bacteria isolated from these samples, making easier the isolation of rare bacterial species. Some bacterial species that were minor before soil drying became dominant in dried soil samples. In general, soil drying allowed the diversity of soil bacteria to be determined more adequately. The bacteria that were isolated from dried soil samples turned out to be resistant to gamma radiation (with LD90 = 2.8-4.6 kGy) and desiccation. It is concluded that soil drying may serve as a model for the action of stress factors on natural bacterial populations. The hypothesis that periodic desiccation was the primary cause of formation of bacterial radioresistance in nature is discussed.
Bacteria↗
[Effect of UV-radiation and drying on bacterium diversity in soil].
It has been shown that after DNA-injuring factors (UV irradiation or drying) action on soil one could observe the decrease of the total quantity of bacteria and the number of species, i.e., the decrease of microbe diversity. At the same time not numerous species were found in soils after their action. Thus the drying or UV-irradiation makes it possible to estimate more completely the microbe diversity in soils as well as to find resistant bacteria. It has been established that the strain Methylobacterium extorquens, M. mesophilicum, Bacillus subtilis, B. cereus, which were isolated after UV irradiation or drying of oil samples, were characterized by high resistance to gamma-irradiation (LD99.99--5-10 kGr). Bacteria (representatives of Pseudomonas genus) sensitive to drying or UV-irradiation were also sensitive to ionizing radiation (LD99.99--0.09 kGr). Nocardieforms and representatives of Myxococcus occupied intermediate position between representatives of genera Methylobacterium and Pseudomonas as to resistance to the above-mentioned stress agents.
Bacteria↗
[Identification of Methylobacterium strains using sequence analysis of 16S rRNA genes].
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Genes, Bacterial↗
[Search for psychrophilic methylotrophic bacteria in biotopes of the Antarctica].
Psychrotolerant bacteria which use obligately methane were found in the moss samples and in soil-vegetation samples in the island part of the Antarctica during the VII expedition (2003) at the station "Akademik Vernadsky". The number of methane-oxidizing bacteria in the samples from the Antarctica (101- 10(3)/g of the sample) was lower than in the samples from the regions with moderate climate (10(2)- 106/g of the sample). Psychrotolerant strains of Methylobacteriium genus which use facultatively methanol were found in the bottom sediments of the fresh-water and Krasnoye lakes, as well as in the soil-plant samples. The psychrophilic strain which is probably a new species of the genus Methylobacterium has been isolated from one soil-plant sample from the Antarctica at 10 degrees C. It is established that most collection mesophilic strains of Methylobacterium, which have been isolated from the soil and plant phyllosphere in Ukraine, also could grow at 10 degrees C.
Adaptation, Biological↗
[Reclassification of thermophylic methane-oxidizing bacteria with the use of sequence-analysis of 16S rRNA genes].
The authors have performed sequence-analysis of 16S rRNA genes of thermophylic methane-oxidizing bacteria UCM B-3026, UCM B-3032, UCM B-3109, UCM B-3014 which were isolated from sludge pond of different regions in Ukraine and deposited at Ukrainian Collection of Microorganisms (UCM) as Methylococcus thermophilus and "M. gracilis". A comparative analysis of 16S rRNA gene sequences of the studied bacteria with those sequences of various strains of bacteria in the GenBank databases has shown that the level of similarity of the strains UCM B-3026, UCM B-3032, UCM B-3109 with Methylocaldum szegediense was 98.0-98.7%, strain UCM B-3014 with Methylocaldum gracile--99.1%, that allows to relate them to these species. As to other species of the genus Methylocaldum, these strains had a lower level of similarity (94.8-97.2 %) and with Methylococcus thermophilus ACM 3585T (= IMV-B-3037T = UCM B-3037T)--less than 90%. Thus, the strains UCM B-3026, UCM B-3032, UCM-3109 were reclassified as Methylocaldum szegediense, strain UCM B-3014--as Methylocaldum gracile. When constructing phylogenetic tree based on the comparison of 16S rRNA genes with the use of various algorithms realized in the packages of programs Tree View (version 1.5.2) and ClastalX (version 1.81) certain clusters have formed genera Methylocaldum, Methylococcus and Methylomonas. Genera Methylobacter and Methylomicrobium have formed three clusters, one of the clusters contained two species of Methylobacter and two species of Methylomicrobium. Apparently, the taxonomy of genera Methylobacter and Methylomicrobium is to be specified.
Genes, Bacterial↗
[Classification of Methylomonas rubra sp. nov].
Strain Methylomonas rubra 15sh(T), deposited in several collections of microorganisms (NCIMB 11913(T) = UCM B-3075(T) = ACM 3303(T)), is the subject of numerous studies. However, the name of this strain is not valid, primarily due to the phenotypic similarity of the species M. rubra to the species M. methanica. The results of the present study and data available in the literature indicate that M. rubra deserves the status of a separate species. Strains of M. rubra differ from strains of M. methanica in a number of properties, such as the ability to reduce nitrates to nitrites, the structure of intracytoplasmic membranes, and the presence of a new coenzyme Q. The distinctions between the species M. rubra and M. methanica were confirmed by comparison of electrophoretic patterns of their cellular proteins, by results of DNA-DNA hybridization, and by the data from 16S rRNA gene sequencing (the level of phylogenetic homology between these two species was below 95%). Phylogenetic and phenotypic analyses showed that strains of M. rubra cannot be assigned to any species of the genus Methylomonas. Results of polyphasic analysis suggest an independent taxonomic status of strain Methylomonas rubra 15sh(T). This paper contains description of Methylomonas rubra sp. nov. with the type strain 15sh(T) = NCIMB 11913T = UCM B-3075(T) = ACM 3303(T). The nucleotide sequence of the 16S rRNA gene of strain 15sh(T) has been deposited with the GenBank database under the accession number AY995198.
Methylomonas↗
[Lithotrophic metabolic elements in the obligate methylotroph, Methylococcus thermophilus].
Methane oxidizing bacteria oxidize ammonium via hydroxylamine to nitrite. Electrons liberated upon oxidation of hydroxylamine are transported, depending on the conditions, by the components of the respiratory chain either to oxygen or to pyridine nucleotide. In the former case, the process is coupled with ATP synthesis which occurs at the level of terminal oxidase; in the latter case, NAD+ is reduced by the energy-dependent reversed electron flow in the respiratory chain. The level of nitrite accumulation in the culture liquid of methane oxidizing bacteria suggests that the process of ammonium nitrification is a necessary step of their metabolism. Therefore, oxidation of the mineral component of the growth medium (i. e. ammonium) is an additional source of metabolic energy for the obligate methane oxidizing bacterium Methylococcus thermophilus. Operation of the lithotrophic type of mechanism for energy production at the account of ammonium oxidation makes methane oxidizing bacteria similar to nitrifying microorganisms.
Adenosine Triphosphate↗
[A needle electrode for measuring the redox potential of media in culturing obligate anaerobes].
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Bacteria, Anaerobic↗
[Subordination of the taxa of gram-negative bacteria determined by numerical analysis methods].
Various numerical methods were used to estimate the coordination of taxa of gram-negative aerobic and facultative anaerobic organoheterotrophic and chemolithotrophic bacteria. Stable phena were found to be formed by cultures belonging to the families Rhizobiaceae, Halobacteriaceae, Enterobacteriaceae, Nitrobacteriaceae (except the genus Nitrobacter), and Methylomonadaceae (except the genus Methylococcus). The unstable position was found in the genera Thermus, Zoogloea, Xanthomonas, Sulfolobus, Methylococcus, Alcaligenes, Brucella, and Acetobacter. The greatest scatter among the objects being analysed was detected among genera belonging to the family Pseudomonadaceae. The taxonomic position of these genera must be defined more precisely. The family Methylomonadaceae is related to such physiologically unique groups of microorganisms as nitrifying, sulfate-reducing, extreme thermophilic and halophilic forms. All in all, the data reported in this work show that numerical analysis can be used to specify the classification structure of bacteria. In a number of cases, the results are consistent with those changes which are performed in the Bergey Manual 9 using logical analysis (for instance, concerning the position of the genera Gluconobacter, Acetobacter, Beijerinckia, and Derxia).
Bacteriological Techniques↗
[Ability of obligate methylotrophs to perform nitrogen fixation].
The ability for nitrification was studied among mesophilic and thermophilic cultures of obligate methylotrophs Methylobacter ucrainicus, Methylomonas methanica, and Methylococcus thermophilus. The strains were almost incapable of nitrification under autotrophic conditions. In the presence of methane, however, they oxidized NH+4 TO NO-2: over 150 mg/litre NO-2 nitrogen was found in the cultural broth. Therefore, obligate methylotrophs are capable of heterotrophic nitrification. The level of nitrification suggests that it is not a side reaction but a necessary stage of the metabolism of obligate methylotrophs. The phenotype relation between obligate methylotrophs and nitrifying organisms is discussed.
Bacteria↗
[Refinement of the diagnosis of the genera and species of methane-using bacteria].
The diagnoses of taxons have been corrected for methane assimilating bacteria of the family Methylomonadaceae Leadbetter 1974, of the genera Methylomonas Leadbetter 1974. Methylococcus Foster a. Davis 1966, Methylosinus Whittenbury. Phillips a. Wilkinson 1970, Methylocytis Whittenbury, Phillips a. Wilkinson 1970, and of 16 species. The diagnosis of the species Methylomonas rubra Whittenbury, Phillips a. Wilkinson 1970 has been completed, and the new species Methylomonas gracilis sp. nov. and Methylococcus luteus sp. nov. have been described. Since information about the properties of certain strains is not complete, they should be transferred to the category incertae sedis. Diagnostic keys for identification of methane assimilating bacteria are presented in the paper.
Methane↗
[Preservation of gas mixtures in gasometers].
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Bacteriological Techniques↗