[Effect of light-isotope water on growth of bacterial culture].

The stimulating effect of light-isotope water on microbial growth was demonstrated in bacterial culture Pseudomonas esterophilus. Nutrient medium was prepared of mineral salts and ethyl acetate as a source of carbon dissolved in light-isotope water with ppm 35 and 70; the control medium contained same components dissolved in distilled water. The investigation showed an increase in the number of bacterial cells in the exponential stage of growth in static culture in light-isotope water as compared with the control. Specifically, accretion made up 87.3 and 35.2% in light-isotope water with ppm 35 and 70, respectively. In an hour, the number of cell divisions increased by 6.7% and 3.3%, respectively. Therefore, light-isotope water stimulates the metabolic activity and, consequently, growth of bacterial cells.

[Iodine-containing urine preservative].

One of the formidable problems of exploration missions is creation of autonomous water-closed life support systems. Sources of water for regeneration could be various water-containing human wastes including urine, the most chemically contaminated liquid. Prior to physical/chemical regeneration, urine first must be decontaminated in order to put a stop to microbiological processes that form harmful and volatile compounds contaminating condensate and drastically reducing the service life of afterpurifucation filters. Bactericide, sporocide and fungicide effectiveness of two iodine-containing preservatives was tested. One of them contains a water solution of iodine--potassium iodide and sulphuric acid. The other has medical poly-vinyl pyrrolidone to neutralize iodine toxicity. The broad antimicrobial spectrum of two iodine-containing urine preservatives and adaptability of microorganisms to a new environment are key arguments for serial use of these and other preservatives in regenerative physical/chemical systems of water supply in space exploration missions.

[Biodegradation of methyl and ethyl acetates by immobilized Pseudomonas esterophilus cells].

A biofilter based on polyvinylformal foam and Pseudomonas esterophilus strain VKM V-1436D cells, which utilize methyl and ethyl acetates as sources of carbon and energy, was created. A complete conversion of methyl and ethyl acetate (2000 mg/l) under flow conditions was reached. Because carboxyl esterase does not exhibit specificity for these esters, no adaptation period was required for switching the biofilter between biodegradation of methyl acetate and ethyl acetate.

[Biotransformation of organic substances by an immobilized associative bacterial culture]. / Biotransformatsiia organicheskikh veshchestv immobilizovannoi assotsiativnoi bakterial'noi kul'turoi.

Bacterial strains were screened to transform to end-products (carbon monoxide and water) elevated concentrations of acetone, acidic acid, and ethanol in a biocatalyst with an immobilized bacterial association cultivated on solid foam polyvinyl acetate (FPVA). The innocuous association amalgamated Paracoccus denitrificans VKM V-1324, Pseudomonas esterophilus VKM V-1736D and Achromobacter parvulus VKM V-1541D. The biocatalyst was tested with the help of classic methods and equipment for microbes cultivation. Microbial growth was assessed in the optical density units. Comparative evaluation of the biocatalytic activity was performed on gas-chromatographer Pue Unicam-104. Based on test results, specific rates of oxidation of acidic acid, ethanol and acetone per one g of FPVA were 0.75, 0.72, and 0.67 mg/hr, respectively.

[Principles of developing methods for decontamination and preservation of water-containing human wastes in a mission to Mars]. / Printsipy podkhoda k razrabotke sredstv obezzarazhivaniia i konservatsii vodosoderzhashchikh otkhodov zhiznedeiatel'nosti cheloveka primenitel'no k marsianskoi ékspeditsii.

Chemical and microbial safety will be one of the major functions of a closed eco-system aboard piloted interplanetary vehicle. Methods for decontamination and preservation of water-containing human wastes (WHW) should be developed on the assumption that WHW are a labile biochemical system biological and chemical processes of which are intricately dependent on preservatives, regenerative water quality, structural material off-gassing, and methods of WHW collection, storage, and management.

[Microbial destruction of harmful organic contaminants inherent to atmosphere of living space]. / Mikrobiologicheskaia destruktsiia vrednykh organicheskikh primesei, svoistvennykh atmosfere obitaemykh pomeshchenii.

The investigation into the microbial destruction of harmful organic contaminants in the air of habitable rooms was performed with the assumption that microorganisms have labile metabolism and synthesize inducible enzymes involved in transformation of organics compounds. Based on our observations, Methylobacterium D-08 and Arthrobacter pastens are able to synthesize inducible enzymes and transform ethanol, acetic acid, acetone, and aldehyde. Association of these microorganisms does not reveal acute antagonism in case of co-cultivation on mineral substrates with carbon provided by ethanol, acidic acid, acetone, and acetate aldehyde. The most rapid growth of microorganisms was observed at 28 degrees C and pH 7. Determination of the effects of different concentrations of harmful organics on carbon dioxide production by the microbial association showed that the threshold concentration of acetate aldehyde was close to 2 mg/l and acetone--4 mg/l. The transformation activity was not reduced even at the ethanol and acidic acid concentrations of 80 and 100 mg/l, respectively. The association of A. pastens and M.D-08 oxidized ethanol, acidic acid, acetone and acetate aldehyde to carbon dioxide and water up to 90%.

[Immobilized biocatalysts in biotechnological processes]. / Immobilizovannye biokatalizatory v biotekhnologicheskikh protsessakh.

In recent years, biotechnology has been stuck with the problem of choosing the most technologically convenient way of utilization of biocatalysts using bacterial cells or structural formations. Immobilization of bio-objects on solid carriers uses the advantages of heterogenic catalysis over homogenous like simple separation of byocatalyst from end product on completion of biotechnological process, and highly effective transformation or synthesis of organic compounds through biomass concentration in fermenter. In addition, immobilized biocatalysts exhibit better stability in case of exposure to aggressive temperatures, active environmental reactions, and "attack" of foreign microflora. Immobilized biocatalyzers can operate repeatedly and owing to the unique specificity show promise for wide application in aerospace and environmental medicine.

[Stable oxygen and carbon isotopes in biological studies]. / Stabil'nye izotopy kisloroda i ugleroda v biologicheskikh issledovaniiakh.

Biogenic chemical elements in the Earth biosphere are presented both by light and heavy stable isotopes (16O and 18O, 12C and 13C). Because of inequality of these isotopes the light ones dominate in the exchange processes between the animate and inanimate nature and this leads to changes in the ratios of isotope modifications in the environment. A comparatively constant isotopic composition of the Earth atmosphere is primarily maintained by water. It is the heavy carbon isotope that inputs to the most isotope-heavy compounds such as marine carbonates within the atmosphere--hydrosphere system. As in nature, biogenic isotopes fractionate inside hermetically sealed habitats with the regenerative life-support systems; however, the mechanism of relative stability of the isotope composition is unknown. The problem of providing the best isotopic composition of biogenic chemical elements aboard manned space vehicles was first raised by Yu.Ye.Sinyak and A.I. Grigoriev in 1996. The review contains the data on the levels of oxygen isotopes and photosynthetically generated oxygen in water pools in different regions of the Earth. discussion of the ratios of the oxygen and carbon isotopes in the atmospheric carbon dioxide, and the range of isotopes variations and presumed "sites" of isotopes fractionating in cellular structures of autotrophs. The wealth of literary findings effectuates the conclusion that artificial environments for humans should reproduce the natural relationships and variations of biogenic isotopes. Yet, what biogenic isotopes ratios are desirable aboard manned space vehicles can be determined in extensive investigations of the effects of various modifications of stable isotopes on humans with due account for the unfavourable factors of space flight.

[Immobilized catalase in water purification systems]. / Immobilizovannaia katalaza v sistemakh ochistki vody.

The results of studies on producing the biocatalyst based on catalase immobilized in the fibers from triacetate are presented. The catalase producer is Penicillium fungus. Catalase was produced by precipitation with the use of ethyl alcohol from the cultural fluid with separate and unseparate mycelium. The highest activity of catalase in the cultural fluid is seen on the nutrient medium containing 4% of carbon source. For immobilization the water solution of enzyme was concentrated in the vacuum-rotor evaporator at temperature of 25 degrees C. The enzyme was included in the structure of fibers during the process of their formation. Of the fiber-producing polymers (cellulose triacetate, chlorine, polysulphone) the most enzymatic activity has the catalase-containing fibers derived from the cellulose triacetate, in this case, the fine fibers of biocatalyst have the higher specific activity. It is established that the fibers obtained by using catalase of microbiological origin possess high stability and their activity does not practically change in the aqueous environment. The unpurified catalase is one and a half higher than at purified catalase. Under laboratory conditions there turned out the experimental batches of fibers and there conducted their endurance tests. Catalase included in cellulase triacetate has effectively functioned during a period of 2 years purifying the distilled water containing 50 mg/l of hydrogen peroxide.

[Biocatalysis using immobilized cells or enzymes as a method of water and air purification in habitable enclosed environment]. / Biokataliz na osnove immunobilizovannykh kletok ili fermentov kak odin iz podkhodov k ochistke vody i atmosfery v obitaemom germoob"ekte.

This paper shows that the method of water and air purification using immobilized cells and enzymes can be applied in regenerative life support systems in a habitable enclosed environment. This method is based on selective and adaptive functions of enzymic systems of microorganisms to assimilate organic components of the medium to be eliminated. Advantages of biocatalysis are low energy requirements and mild temperatures of purification leading to practically complete elimination of the substrate. Due to immobilization, cells and enzymes constitute an independent component which can be added to any continuously operating system of purification without generating a specific interface which is crucially important in microgravity. This allows the process of purification to be controllable. The resulting water and air meet biological requirements because they are formed under the influence of living organisms as in natural biogeocenoses. The production of ecologically pure water and air is highly important for long-duration space missions, especially for flights to Mars.

[Effectiveness of urine-preserving agents used in water reclamation systems]. / Issledovanie éffektivnosti konservantov mochi primenitel'no k regenerativnym sistemam vodoobespecheniia.

The antimicrobial activity of 11 chemicals of different classes was investigated having in view their potential use as urine conserving agents onboard space flying vehicles. The investigations were performed on 8 bacterial cultures, including spore-forming, urease-active bacteria and microorganisms that typically occur in the spacecraft environment. Out of the chemical tested, five haloid-containing agents, primarily oxidative agents, showed the largest spectrum of antimicrobial action and highest bactericidal effect. These agents are recommended to be used as urine conserving agents in water reclamation systems during space flights.

[Study of the toxic properties of preservatives used in water reclamation systems]. / Issledovanie toksicheskikh svoistv konservantov, prednaznachennykh dlia ispol'zovaniia v sistemakh regeneratsii vody.

The comparative toxicity of halogen-containing oxidizing agents was investigated with the purpose of their utilization as urine preservatives in water reclamation systems. It was found that the high toxicity of the agents (LD50 of agent 1 was 15.7 +/- 1.1 mg/kg and LD50 of agent 2 was 23.0 +/- 1.2 mg/kg when injected i.p. to white mice) was distinctly related to their low pH in water solutions (pH 3-4). In neutral solutions the toxicity of agent 1 decreased 35 times and that of agent 2-12 times so that they can be classified as moderately toxic substances. Using an isolated frog heart according to Straub, it was shown that solution neutralization with 20% NaHCO3 also decreased the toxic effect of the above agents, making them similar to chloramine B, a well-known disinfectant. The above agents were found to be rapidly inactivated when stored in low concentrations and to remain highly stable when stored in concentrated solutions.

[Comparative evaluation of the antimicrobial activity of urine preservatives]. / Sravnitel'naia otsenka antimikrobnoi aktivnost' nekotorykh konservantov mochi.

New antiseptics were examined for their antimicrobial activity with respect to the microorganisms that are most likely to occur in the urine subject to prolonged storage. Chlorine- and iodine-containing compounds were found to have the highest antimicrobial activity combined with a wide spectrum of antimicrobial action. The antimicrobial effect of these compounds was mostly expressed in regard to the typical representatives of urobacteria that actively hydrolyze urea to yield ammonia during prolonged storage of urine.