[Bioremediation of oil-polluted soils: using the [13C]/[12C] ratio to characterize microbial products of oil hydrocarbon biodegradation].

We compared data on the extent of bioremediation in soils polluted with oil. The data were obtained using conventional methods of hydrocarbon determination: extraction gas chromatography-mass spectrometry, extraction IR spectroscopy, and extraction gravimetry. Due to differences in the relative abundances of the stable carbon isotopes (13C/12C) in oil and in soil organic matter, these ratios could be used as natural isotopic labels of either substance. Extraction gravimetry in combination with characteristics of the carbon isotope composition of organic products in the soil before and after bioremediation was shown to be the most informative approach to an evaluation of soil bioremediation. At present, it is the only method enabling quantification of the total petroleum hydrocarbons in oil-polluted soil, as well as of the amounts of hydrocarbons remaining after bioremediation and those microbially transformed into organic products and biomass.

[Ratio [13C]/[12C] as an index for express estimation of hydrocarbon-oxidizing potential of microbiota in soil polluted with crude oil].

The hydrocarbon-oxidizing potential of soil microbiota and hydrocarbon-oxidizing microorganisms introduced into soil was studied based on the quantitative and isotopic characteristics of carbon in products formed in microbial degradation of oil hydrocarbons. Comparison of CO2 production rates in native soil and that polluted with crude oil showed the intensity of microbial mineralization of soil organic matter (SOM) in the presence of oil hydrocarbons to be higher as compared with non-polluted soil, that is, revealed a priming effect ofoil. The amount of carbon of newly synthesized organic products (cell biomass and exometabolites) due to consumed petroleum was shown to significantly exceed that of SOM consumed for production of CO2. The result of microbial processes in oil-polluted soil was found to be a potent release of carbon dioxide to the atmosphere.

[Bacterial methane generation and methods of its optimization].

Presented are the results of studying bacterial methane generation and oxidation in the body of solid domestic wastes dump and intensity of gas release into atmosphere. The investigation revealed active microbial degradation of organic wastes with a distinct biogeochemical zoning. Quantitative and qualitative composition of micro-organisms depends on the depth of horizon. Disintegration of organic components of warehoused foods by various microorganisms occurs with production of volatile and gaseous compounds (carbonic acid, methane and others). Anaerobic conditions set the scene for active production of biogas, major components of which are methane and CO2. The final process in the sequence of organics transformations within the body of solid domestic wastes dump is predominant production of CH4 and CO2 in the ratio of approximately 60 and 40%, respectively, and trace quantities of other volatile compounds. Active bacterial methane oxidation is evidenced by the 13C isotope increase in methane and decrease in carbonic acid. The developed model of animal and plant wastes management demonstrated efficiency of the system using frozen-dried preparations of microbial associations and its practicability in municipal economy.

[Changes of chlorine isotope composition characterize bacterial dehalogenation of dichloromethane].

Fractionation of dichloromethane (DCM) molecules with different chlorine isotopes by aerobic methylobacteria Methylobacterium dichloromethanicum DM4 and Albibacter nethylovorans DM10; cell-free extract of strain DM4; and transconjugant Methylobacterium evtorquens Al1/pME 8220, expressing the dcmA gene for DCM dehalogenase but unable to grow on DCM, was studied. Kinetic indices of DCM isotopomers for chlorine during bacterial dehalogenation and diffusion were compared. A two-step model is proposed, which suggests diffusional DCM transport to bacterial cells.

[A non-invasive method of evaluation of Helicobacter pylori urease activity: its perfection and introduction to clinical practice].

The authors have developed a highly sensitive method of non-invasive diagnostics of Helicobacter pylori, the most frequent human infection. Detection of urease activity is based upon measurement of the degree of the elevation of stable 13C isotope content in exhaled air after administration of C-urea as a test reagent. The method has been scarcely applied in Russia because the test preparation, 13C urea had not been produced domestically until 2002. The method can be easily applied by any healthcare institution; however, it requires special equipment and trained personnel to perform measurement of 13C content in exhaled air samples using mass spectrometers. The article presents the first experience in clinical application of the method.

[Use of carbon isotope composition for characterization of microbial activity in arable soils].

The effect of glucose on microbial mineralization of soil organic matter (SOM) was studied in arable soil specimens. The flows of carbon dioxide generated during this degradation were deduced from differences in the carbon isotope ratios of glucose (delta13C = -11.4 per mil) and SOM (delta13C = -27.01 per mil). The priming effect of glucose and respiratory quotient (RQ) were taken as indices of activation of SOM-consuming microbiota. The data on microbial mineralization of organic matter in soil, obtained in this study, show that addition of a readily consumable substance (glucose) to soil favors SOM degradation and increases the release of carbon dioxide from soil to atmosphere.

[Anaerobic formation of succinate and facilitation of its oxidation -- possible mechanisms of cell adaptation to oxygen deficiency]. / Anaérobnoe obrazovanie suktsinata i oblegchenie ego okisleniia-- vozmozhnye mekhanizmy adaptatsii kletki k kislorodnomu golodaniiu.

An important role of anaerobic formation of succinate in anoxic and hypoxic states and the activation of succinate oxidation under hypoxia were shown. It was concluded that, for maintaining the energetics of animal cells under conditions of oxygen deficiency, it is advisable to use substrates capable of participating in the anaerobic formation of succinate, whereas under hypoxia it is reasonable to use succinate itself.

[Evaluation of glucose utilization in patients with insulin-independent diabetes mellitus by using breathing test]. / Kharakteristika utilizatsii gliukozy s pomoshch'iu 13C-neinvazibvnogo dykhatel'nogo testa pri insulinnezavisimom sakharnom diabete.

Commonly used clinical and biochemical parameters, such as the content of glucose, insulin, somatotropic hormone, triglycerides, lactate, pyruvate, and free fatty acids (FFA) in blood of practically healthy subjects and in patients with insulin-independent diabetes mellitus (IIDM), were compared with the parameters obtained by mass-spectrometric analysis of 13CO2 in expired air after 13C-glucose loading. It was shown that, as opposed to healthy subjects, the content of blood glucose and free fatty acids in patients with IIDM increased, the level of glucose dropped in progression upon short-term fasting, and the concentration of lactate changed both upon fasting and after the administration of small test doses of glucose. The use of the 13C-glucose breathing test (13C-GBT), which presupposes the loading of safe small doses of glucose enriched in 13C-isotope permitted one to reveal a number of novel quantitative diagnostic criteria for the evaluation of glucose metabolism in patients with IIDM: a decrease in the rate of 13C withdrawal as a constituent of expired carbon dioxide after the administration of 13C-glucose; a reduction in the amount of exogenous glucose metabolized to carbon dioxide; and increased oxidation of endogenous substrates participating in carbon dioxide formation. Small glucose loads proposed by the authors in 13C-GBT are safe for patients with diabetes mellitus and have no effect on the level of blood glucose in healthy persons. The parameters determined by noninvasive 13C-GBT are more sensitive for diagnosis than commonly used biochemical characteristics of blood in patients with IIDM. The diagnostic criteria obtained allow the prediction of the maximum prohibited glucose loading for every patient.

[Mass-spectrometric study of the mechanism of microbial oxidation of 3-pyridinaldehyde]. / Mass-spektrometricheskoe izuchenie mekhanizma mikrobiologicheskogo okisleniia 3-piridinal'degida

In order to clarify mechanisms of nicotinic acid synthesis during microbial transformation of 3-methylpyridine, microbial and spontaneous air oxygen oxidation of 3-pyridinaldehyde to nicotinic acid in the H218O environment was studied. It was shown that during spontaneous oxidation the label was incorporated into one atom of oxygen in the carboxylic group of nicotinic acid. During the microbial oxidation the label was equally incorporated into both atoms of oxygen in the carboxylic group of nicotinic acid. It is concluded that the mechanisms of spontaneous and microbial oxidation of 3-pyridinaldehyde are different. It is suggested that the possible precursor of nicotinic acid during microbial oxidation may be hydroxy-3-pyridinaldehyde.

[The Use of the abundance ratio of 13C and 12C isotopes for characteristic of the origin of ethyl alcohol]. / Ispol'zovanie otnoshenii rasprostrannennostei izotopov 13C i 12C dlia kharakteristiki proiskhozhdeniia étilovogo spirta.

During alcohol fermentation, the carbon isotope composition of ethyl alcohol produced depended on the substrate used and was characterized by the value of delta 13C equal to -24.7 +/- 0.8/1000 (wheat grain), -22 +/- 0.1/1000 (rye grain), -22 +/- 0.5/1000 (products of wood hydrolysis), -15.3 +/- 0.3/1000 (maize grain) and -10 +/- 0.1/1000 (sugar cane). The isotope composition of carbon of ethyl alcohol obtained during catalytic hydroxylation of ethylene has a delta 13C of -30.6 +/- 0.3/1000. The possibility of quantitative determination of specific components in mixtures of ethanol samples with various isotope compositions (chemical synthesis and alcohol fermentation of raw material from C3- or C4-plants) was shown.

[Scientific principles of complex ecologically-safe technology of mustard gas destruction]. / Nauchnye osnovy kompleksnoi ékologicheski bezopasnoi tekhnologii unichtozheniia iprita.

The principles of complex, ecologically-safe technology for the destruction of battle gas mustard were worked out. This technology was based on the reaction alkaline detoxication of mustard; the major component of reaction mixture obtained after detoxication was thiodiglycol. Thorough thiodiglycol mineralization was achieved by electrochemical treatment. Electrolysis products were biologically utilized in biosorber.

[Application of 13C mineral carbon for assessment of the primary production of organic matter in aquatic environments].

The possibility of measuring the rates of light and dark CO2 assimilation using 13C carbonate was demonstrated on Lake Kichier (Marii El). The application of methods utilizing the stable 13C and the radioactive 14C isotopes resulted in comparable values of the rates of light and dark CO2 fixation. Due to its absolute environmental safety, the method with 13C mineral carbon can be recommended as an alternative to radioisotope methods for qualitative measurements of CO2 fixation rates in aquatic ecosystems.

[Study of the initial reaction of enzymatic oxidation of 1,8-dimethylnaphthalene]. / Izuchenie nachal'noi reaktsii fermentativnogo okisleniia 1,8-dimetilnaftalina

Crude enzymatic preparation has been obtained from Pseudomonas bacteria which oxidises 1,8-DMN during 10-hour incubation with the following formation of the same products which are formed when this compound is oxidized by the intact cells. The first product of the oxidation is 1-methyl-8-oxymethylnaphtalene (compound I), obtained as a result of hydroxylation of one methyl group. Probably hydroxylase of 1,8-DMN may be referred to the class of oxigenases of the basis of the absence of 18O incorporation from H218O to compound I, and also resulting from the data on absorption of molecular oxygen during the reaction. The enzyme is completely inhibited by chelating agents of Fe2+ NAD(P)H and Fe2+ stimulates the reaction of 1.8 DMN oxidation.

[Fractionation of sulfur isotopes by phototrophic sulfur bacterium Ectothiorhodospira shaposhnikovii]. / Fraktsionirovanie izotopov sery fototrofnymi serobakteriiami Ectothiorhodospira shaposhnikovii

Two processes of sulphur isotope fractionation have been found in experiments with the sulphur purple bacterium Ectothiorhodospira shaposhnikovii. As a result, a light isotope, 32S, is concentrated in residual hydrogen sulphide, and a heavy isotope, 34S, in elementary suphur which is deposited outside the cell. The sulphate produced is lighter than elementary sulphur. Fractionation of sulphur isotopes is observed in natural conditions and is confined to places of mass growth of photosynthetic sulphur bacteria.

[The fractionation of chlorine isotopes by the aerobic methylotrophic bacterium Methylobacterium dichloromethanicum grown on dichloromethane]. / Fraktsionirovanie izotopov khlora aérobnymi metilotrofnymi bakteriiami Methylobacterium dichloromethanicum pri roste na dikhlormetane.

Methylobacterium dichloromethanicum was found to be able to utilize dichloromethane (DCM) as the source of carbon and energy with the production of biomass, CO2, and HCl. A comparative analysis of abundances of the major DCM isotopomers 35Cl(2)12C1H2, 35Cl37Cl12C1H2 and 37Cl(2)12CH2 made it possible to estimate the fractionation of chlorine isotopes during the bacterial metabolism of DCM. The kinetic chlorine isotope effects for 35Cl37Cl12C1H2 (m/z 86) and 37Cl(2)12C1H2 (m/z 88) relative to 35Cl(2)12C1H2 (m/z 84) turned out to be alpha 86/84 = 1.006 +/- 0.002 and alpha 88/84 = 1.023 +/- 0.003, respectively. The inference is made that the growth of M. dichloromethanicum on DCM is accompanied by the mass-independent fractionation of the DCM isotopomers.

[Fractionation of stable sulfur isotopes during microbiological processes in Slavyansk lakes]. / Fraktsionirovanie stabil'nykh izotopov sery pri mikrobiologicheskikh protsessakh v Slavianskikh ozerakh

The isotopic content of sulphur in sulphates increases with depth in waters containing hydrogen sulphide of the meromictic lakes Repnoe and Veisovo as a result of microbiological reduction of sulphates. At the same time, hydrogen sulphide enrichments 19 to 25% of the light isotope 32S in the lake Veisovo, and 24 to 32% in the lake Repnoe. The fractionation of sulphur isotopes, manifested in the enrichment of sulphides with lighter isotopes, and that of sulphates with heavier isotopes, was found also in the bottom deposits of the lake Repnoe. The isotope and microbiological data suggest that, in the zone of mass growth of the phototrophic sulphur bacteria in the lake Repnoe, there are two processes of fractionation: (a) due to the bacterial reduction of sulphates; and (b) due to anaerobic oxidation of hydrogen sulphide, resulting in the enrichment of hydrogen sulphide with the light isotope 32S by 5 to 7 promille.

[Thiosulfate as an intermediate product of bacterial sulfate reduction]. / O tiosul'fate kak promezhutochnom produkte bakterial'noi sul'fatreduktsii.

Sulfur compounds produced at intermediate stages during transformation of sulfate to sulfide were analyzed in experiments with a culture of sulfate reducing bacteria. Small quantities of thiosulfate can accumulate in the medium at the beginning of growth of the sulfate reducing bacterium. The data are discussed and compared with the results of Chambers and Trudinger (1975) who could not detect thiosulfate in similar experiments.