[The role of low-molecular-weight nitrogen compounds in the osmotolerance of Rhodococcus erythropolis and Arthrobacter globiformis]. / Rol' nizkomolekuliarnykh azotistykh soedinenii v osmotolerantnosti bacterii rodov Rhodococcus i Arthrobacter.

Investigations showed that Rhodococcus erythropolis E-15 and Arthrobacter globiformis 2F cells respond to osmotic shock by increasing the synthesis of free amino acids, primarily glutamic acid (80% of the intracellular free amino acid pool). The osmoprotective role of glutamic acid follows from its beneficial effect on the growth of bacteria in high-salinity media. It was found that the addition of this amino acid to the growth medium at a concentration of 2 mM shortened the lag phase and increased the growth rate and biomass yield of either of the two bacteria. The addition of another osmoprotectant, trehalose, to the high-salinity growth medium of R. erythropolis E-15 at the same concentration (2 mM), restored the growth parameters of this bacterium to the control values.

[Bacterial succession on n-alkanes under the conditions of sulfate reduction]. / Bacterial'naia suktsessiia na n-alkanakh v usloviiakh sul'fatreduktsii.

The dynamics of species composition of a hydrocarbon-oxidizing bacteriocenosis of a ground suspension of Mozhaisk Reservoir has been studied. The bacteriocenosis was undergoing development in a paraffin film (model association composed of sulfate-reducing bacteria and hydrocarbon-oxidizing bacteria). The type of bacterial succession did not depend on the depth, from which ground samples were collected. Two microbial species (Pseudomonas sp. and Arthrobacter globiformis) were absolutely dominant. Pseudomonas sp. was dominant at the early and intermediate stages of the succession, whereas A. globiformis was present in the hydrocarbon-oxidizing bacteriocenosis throughout the whole period of the succession. There was a trend toward a gradual increase in the ratio of A. globiformis, and, by the end of the experiment, Pseudomonas sp. was replaced by A. globiformis almost completely. The bacterial species Micrococcus sp. and Rhodococcus erythropolis were minor components of the hydrocarbon-oxidizing bacteriocenosis under the conditions of sulfate reduction. The succession of species of hydrocarbon-oxidizing bacteria in the paraffin film of the model association reflects both the life strategy of the bacterial species under study and the degree of their tolerance to products of sulfate reduction.

[Extracellular metabolites of hydrocarbon-oxidizing bacteria as a substrate for sulfate reduction]. / Vnekletochnye metabolity uglevodorodokisliaiushchikh bakterii kak substrat dlia razvitiia sul'fatreduktsii.

The relationship between bacterial oxidation of hydrocarbons and sulfate reduction was studied in the experimental system with liquid paraffin was used as a source of organic compounds inoculated with silt taken from a reservoir. Pseudomonads dominated in the hydrocarbon-oxidizing silt bacteriocenosis. However, Rhodococcus and Arthrobacteria amounted to not more than 3%. Arthrobacteria dominated the microbial association formed in the paraffin film of the model system. Sulfate-reducing bacteria were represented by genera Desulfomonas, Desulfotomaculum, and Desulfovibrio. The growth of sulfate-reducing bacteria in media containing with paraffin, successive products of its oxidation (cetyl alcohol, stearate, and acetate), and extracellular metabolites of hydrocarbon-reducing bacteria was studied. The data showed that sulfate-reducing bacteria did not use paraffin or cetyl alcohol as growth substrates. However, active growth of sulfate-reducing bacteria was observed in the presence of stearate and extracellular water-soluble or lipid metabolites of Arthrobacteria.

[Esterase activity of hydrocarbon-oxidizing bacteria]. / Esteraznaia aktivnost' uglevodorodokisliaiushchikh bakterii.

The activity of esterase was studied in bacteria oxidizing hydrocarbons and belonging to the genera Rhodococcus, Arthrobacter and Pseudomonas. Indophenyl acetate was used as a substrate of the reaction catalysed by the enzyme. Exocellular esterases were not found. Endocellular esterases differed in their activity and thermostability both among the genera and among species of one and the same genus.

[Bacterial interaction in a culture containing Pseudomonas and Mycobacterium in relation to hydrocarbon oxidation]. / Vzaimodeistvie bakterii v kul'ture, soderzhashchei Pseudomonas i Mycobacterium, v sviazi s okisleniem uglevodorodov.

An experimental association of Pseudomonas and Mycobacterium was employed for a more complete oxidation of a hydrocarbon substrate. The maximum effect of combined cultivation (74% vs. 50 and 47% in the pure cultures of Mycobacterium and Pseudomonas, respectively) was obtained under steady-state conditions. The result is attributed to the processes of co-oxidation and the physiological properties of the microorganisms.

[Chemical composition and role of Pseudomonas aeruginosa peptidoglycolipid in hydrocarbon assimilation]. / Khimicheskii sostav i rol' peptidoglikolipida Pseudomonas aeruginosa v protsesse usvoeniia uglevodorodov.

Pseudomonas aeruginosa P-20 releases a lipophilic compound during growth in a medium with hexadecane. The compound was shown to be a peptidoglycolipid. The peptide moiety consists of 7 amino acids: lysine, aspartic and glutamic acids, serine, proline, valine and leucine. The carbohydrate component is ramnose. The lipid moiety is represented by a mixture of fatty acids with the number of carbon atoms from 11 to 18 among which C11:1, C16:0, C18:1 and C17:3 predominate. The content of unsaturated acids is 64.62%. The peptidoglycolipid stimulates the process of hydrocarbon assimilation.

[Role of emulsification in the process of hydrocarbon absorption by Pseudomonas aeruginosa cells]. / Rol' émul'girovaniia v protsesse pogloshcheniia uglevodorodov kletkami Pseudomonas aeruginosa.

Lipophilic biopolymers from the cell walls of saprophytic mycobacteria were shown to stimulate the process of hydrocarbon assimilation by Pseudomonas aeruginosa cells. This should be attributed to the fact that bacterial peptidoglycolipids emulsify a hydrocarbon facilitating the contact between it and the cells. It has been found experimentally that P. aeruginosa cells growing in the medium with n-alkanes release a factor into the medium. The factor appears to contain peptide chains and is responsible for hydrocarbon emulsification.

[Lipids of a paraffin-oxidizing strain of Pseudomonas aeruginosa]. / Lipidy parafinokisliaiushchego shtamma Pseudomonas aeruginosa.

The qualitative and quantitative composition of lipids was studied in a paraffin-oxidizing Pseudomonas aeruginosa P-20 strain. The content of free lipids was 7% of the dry biomass weight in a medium with hexadecane and 6.7% in a medium with glucose. The content of bound lipids was 6.7 and 5.6%, respectively. Phospholipids and free fatty acids are main components of lipids in the both cases. Phospholipids are represented by diphosphatidyl glycerol, phosphatidyl ethanolamine, phosphatidyl glycerol, and phosphatidyl choline. The fatty acids of free lipids consist by 72% of even acids with an unbranched carbon chain, among which palmitic and octadecenic acids prevail no matter what is the composition of a medium. 'Uneven' acids are represented mainly by nonadecenic acid: 17.8% in the medium with hexadecane and 15.9% in the medium with glucose. The content of unsaturated acids is 55.95% in 'hexadecane' cells and 44.89% in 'glucose' cells; octadecenic and nonadecenic acids predominate among unsaturated acids. Fatty acids covalently bound to cellular proteins and polysaccharides contain much less unsaturated compounds (particularly in cells grown in the medium with hexadecane) and more branched acids; C18:1, C16:0 and C17:0-branched acids predominate among them.

[Chemotactic reactions of a paraffin-oxidizing strain of Pseudomonas aeruginosa]. / Khemotakticheskie reaktsii parafinokisliaiushchego shtamma Pseudomonas aeruginosa.

The reactions of chemotaxis were studied in a paraffin-oxidizing Pseudomonas aeruginosa strain using the method of migration in viscous media. Diesel fuel and paraffin become attractants only if they are contaminated with hydrocarbon-oxidizing mycobacteria. A suspension of mycobacterial cells as well as their lipids (peptidoglycolipids, wax, triglycerides, methyl esters of mycolic acids) are attractants, too. A mycobacterial biomass containing no lipids does not cause chemotaxis of P. aeruginosa cells.

[Substrate-induced changes in Mycobacterium paraffinicum cells and cell membranes]. / Indutsiruemye substratom izmeneniia kletok i kletochnykh obolochek Mycobacterium parafinicum.

The method of spectroscopy of attenuated total reflection (ATR) range was used to study the dynamics of biochemical changes of both the whole cell of Mycobacterium paraffinicum 134 and its outer layer depending on the type of growth substrate. The cells and their outer layers were shown to vary significantly in their composition upon growth in different media. When the cells were cultivated in a medium with glucose, the biosynthesis of structural lipids of the cell wall, viz. glycolipids and mycolic acids, proceeded at a high rate. The quantity of triglycerides produced at the stationary growth phase was also high. When the cells were cultivated in MPB, the content of structural and reserve lipids was very low in both the cell and its outer layer. Therefore, a sufficiently lipophilic cell wall was formed when the cells were grown in the medium with glucose, but it was much less lipophilic when the cells were cultivated in MPB. Consequently, the both types of cells differed in their capacity to absorb a hydrophobic substrate. The paper discusses the role of lipid components in regulating the structure of mycobacterial cell walls depending on a growth substrate.

[Effect of growth conditions on the activity of the enzymes of cyclic 3':5'-AMP synthesis and decay in phototrophic bacteria]. / Bliianie uslovii byrashchivaniia fototrofnykh bakterii na aktivnost' Fermentov sinteza i raspada tsiklicheskogo 3':5'-AMP.

Activity, ratio and summary content of cyclic AMP enzymes, adenylate cyclase and phosphodiesterase varied depending on growth conditions of phototrophic bacteria (Rhodospirillum rubrum and Rhodopseudomonas palustris). It suggests, that membrane-bound and soluble enzymes carry different functions. The increase of adenylate cyclase under chaning growth conditions was usually accompanied by the increase of phosphodiesterase. Sharp increase of both enzymes activity was observed when bacteria were growth in aerobic conditions. The activity of both enzymes in chromatophores was 2.8-fold higher when bacteria were grown in the light in anaerobic conditions, than in chromatophores of bacteria grown under stationary aerobic conditions in the light. It is suggested that 3':5' AMP can participate in autotrophic carbon assimilation or in the synthesis of pigments and other components of bacterial photosynthetizing apparatus. Substitution of NH4+ into NO3- and glutamate under the growing of R. rubrum in anaerobic conditions in the light resulted in the increase of the enzymes activities, which is the evidence of possible role of 3':5' AMP in mineral nitrogen uptake and nitrogen fixation. Glutamate concentration of 4 g/l stimulated the enzymes both in vivo and in vitro. The data obtained suggest that 3':5' AMP can carry multiple functions, participating in regulation of a number of metabolic processes in photorophic bacteria.