[The effect of pH, aeration, and temperature on arachidonic acid synthesis by Mortierella alpina].

The effects of pH, aeration, and temperature on the growth of fungal strain Mortierella alpina LPM-301 and the synthesis of lipids and arachidonic acid in glycerol-containing medium were studied. Arachidonic acid production in the stationary growth phase was found to depend considerably on the pH value; it reached the optimum at pH 6.0 and was irreversibly inhibited at a pH of 3.0. The PO2 values in a range from 10 to 50% showed no marked effect on mycelium growth or the synthesis of lipids and arachidonic acid. The temperature optimum for arachidonic acid production was 20-22 degrees C. Under continuous cultivation, the amount of arachidonic acid reached 29.8% of lipids and 7.4% of biomass. The arachidonic acid yield from the glycerol consumed was 4.1% by mass and 8.8% by energy. It is suggested that arachidonic acid synthesis at an unfavorable pH and elevated temperatures was limited by the activity of A-12-desaturase and by the conversion of linoleic to arachidonic acid, respectively.

[Biosynthesis of arachidonic acid by micromycetes (review)].

Arachidonic acid (ARA, 5,8,11,14-cis-eicosatetraenoic acid) is widely used in medicine, pharmaceutics, cosmetics, dietary nutrition, agriculture, and other fields. Microbiological production of ARA is of increased interest since the natural sources (pig liver, adrenal glands, and egg-yolk) cannot satisfy its growing requirements. Mechanisms for ARA biosynthesis as well as the regulation of enzymes involved in this process are considered. Review summarizes literature data concerning individual stages of microbiological ARA production, methods for screening of active strains-producers, physiological regulation of ARA synthesis in micromycetes (the effect of growth phase, medium composition, pH, temperature, and aeration), and effective technologies of fermentation and the product recovery. Information on the whole biotechnological process from strain selection to the ARA yield improvement and purification of the end product is presented.

EDTA-dependent assimilation of glucose and organic acids by an EDTA-degrading bacterium.

Bacterial strain VKM B-2445 is characterized by ethylenediaminetetraacetate (EDTA) requirement for cell growth. This strain could not grow on glucose and organic acids as the sole sources of carbon and energy, but it was able to metabolize these substrates added to EDTA medium. EDTA initiated assimilation of glucose, succinate, fumarate, malate, and citrate and supplied nitrogen for the biomass production from these substrates. Utilization of primarily nongrowth substrates by strain VKM B-2445 started when EDTA was exhausted or at least considerably degraded.

[Ultrastructural organization and development cycle of soil ultramicrobacteria belonging to the class Alphaproteobacteria].

Gram-negative chemoorganotrophic soil ultramicrobacteria (UMB), strains NF1 and NF3, have been isolated. In their development cycle, the strains formed small coccoid cells of 400-800 nm and ultrasmall cells of 200-300 nm. Phylogenetically, the strains NF1 and NF3 belong to Alphaproteobacteria and are close to the type strain of the recently described species Kaistia adipata. The ultrastructure of UMB cells has been studied using ultrathin sections and freeze-fracturing. It has been shown that the structure of UMB cell walls is of the gram-negative type; the outer membrane and peptidoglycan layer are well differentiated. The cell surface has numerous protrusions (prosthecae) of conical or spherical shape filled with the contents of the periplasm. The formation of unusual cellular structures (not occurring in known free-living bacteria) is a feature of UMB: these include the following: (a) piles of rod-like subunits, ca. 30 A in diameter and 150-250 angstroms in length: (b) long bunches (up to 300-400 angstroms) comprised of filamentous subunits; and (c) large electron-dense spherical bodies (up to 200-300 angstroms in diameter) localized in the periplasm. A distinctive feature of UMB is their ability to grow as facultative parasites on living cyanobacterial (CB) cells. In this case, three types of interaction between UMB and CB have been revealed: (1) adsorption of UMB cells on the surface of CB cells; (2) penetration of UMB into polysaccharide sheathes; and (3) penetration of UMB into CB eytoplasm. UMB cells have been shown to reproduce by budding, with buds (up to 2-3) located directly on the mother cell, without formation of intennediate hyphae.

Link between the early calcium deposition in placenta and nanobacterial-like infection.

The placenta is a vitally important organ in the regulation of embryonic development. That is why extensive calcium deposition [also named as pathological placental calcification (PPC)] could have serious negative consequences for the adequate growth of embryos. The nature and mechanism of PPC development has not been defined as yet. In the present investigation, we have tested the hypothesis that the molecular basis of PPC development consists of nanobacteria-induced calcification in infected female placenta. Electron microscopy findings support this hypothesis. The initial stage of micro-calcification may originate from the external surface of individual nanobacteria-like particles found mainly in placental extracellular matrix, where initial calcium deposition occurs as a needle surface deposition or as an amorphous-like surface precipitate. Further calcific propagation in placenta takes place in the newly formed macro-cavities, which are characterized by low electron density, possibly reflecting its liquid content around calcium deposition. The micro-cavities contain free nanobacterial-like particles, which may relate to atypical Gram-negative bacteria but not to apoptotic bodies by morphological characters and DNA/RNA distribution. We hypothesize that the increased placental calcification might be caused, at least in part, by nanobacterial infection.

[Corrosion of pipe steel samples and conjugated conversion of sulfur compounds by thiobacteria Halothiobacillus neapolitanus DSM 15147].

The kinetics of conversion of sulfur compounds by Halothiobacillus neapolitanus DSM 15147 bacteria was studied in the presence of steel samples. It was shown that the presence of steel altered the known pathway of sulfur compound oxidation by thiobacteria. Production of atomic hydrogen via the interaction between biogenic sulfuric acid and steel enhanced secondary production of intermediates and decreased the content of sulfate produced previously. The process was accompanied by pH elevation and continuation of intense growth of the thiobacterium culture. Thiobacteria formed a corrosive medium, which caused metal destruction. The protective properties of anticorrosive coatings 225 LS and 640 mk were tested. It was shown that these coatings protected steel from the destructive effect of biogenic sulfuric acid.

[Methane production by the sulfate-reducing bacterium Desulfosarcina variabilis]. / Obrazovanie metana cul'fatvosstanavlivaiushchei bakterii Desulfosarcina variabilis.

The sulfate-reducing bacterium Desulfosarcina variabilis VKM B-1694 was found to produce up to 1.62 mumol methane per mg protein when grown on different substrates. The role of methanogenesis and the physicochemical factors determining this process in sulfate-reducing bacteria are discussed.

[About nannobacteria]. / O nannobakteriiakh.

Bacterial nanocells 0.2-0.3 micron in size and hundreds of a cubic micron in volume have been revealed in natural habitats and obtained in pure cultures. The taxonomic analysis of naturally occurring nanobacteria showed that they belong to the known taxa of the kingdom Eubacteria. The results of the cytological investigation of nanocells suggest that they are universally formed in response to stress impacts.

Removal of H2S by the purple sulphur bacterium Ectothiorhodospira shaposhnikovii.

When Ectothiorhodospira shaposhnikovii VKM B-1525 was used for desuphurization of biogas in the laboratory and in a pilot plant, there was complete oxidation of H2S, the main product being elemental sulphur. The advatage of this culture over green bacteria is discussed.

[Effect of hyperbaric oxygenation on the corticosterone content of the blood in experimental acute respiratory distress syndrome]. / Vliianie giperbaricheskoi oksigenatsii na soderzhanie kortikosterone v krovi pri ostrom respiratornom distress-sindrome v éksperimente.

The three series of experiments conducted on 139 adult wistar rats it was found, that two-hour stay of the animals in barochamber under the pressure of 3 atmospheres reduces considerably the percentage of mortality rate and decelerates the development of arterial hypoxemia in rats with an experimental model of acute respiratory distress syndrome (ARDS) reproduced by intrapleural injection of oleic acid (0.27 ml/100 g). Stalle in comparison with the control (I) series elevation of corticosterone in the animal blood II and III series (conduction of HBO correspondingly in 4 and 12 hours from the beginning of the process) is considered as the manifestation of one of the most important mechanism of organism adaptation to the development of acute hypoxia in ARDS.

[Effect of the oxidation-reduction potential of the medium on the production of gentamycin]. / Vliianie okislitel'no-vosstanovitel'nogo potentsiala sredy na obrazovanie gentamitsina.

The medium redox potential had an effect on gentamicin production by Micromonospora purpurea v. violacea, strain VNIIA 7R. The Eh influence was shown to be statistically reliable when the results were expressed in relative units against the control. In the laboratory experiments with low volumes of the medium the Eh increase by more than 170 per cent induced inhibition of gentamicin biosynthesis while the Eh increase by 108 to 168 per cent induced stimulation of the activity.

[Use of hyperbaric oxygenation to correct an acute experimental respiratory insufficiency syndrome]. / Ispol'zovanie giperbaricheskoi oksigenatsii dlia korrektsii sindroma dykhatel'noi nedostatochnosti v éksperimente.

The results of the experiments on 159 Wistar rats have shown that one two-hour session of hyperbaric oxygenation (HBO) under the pressure of 3 ata affects considerably the course of acute respiratory insufficiency syndrome: the mortality rate decreases markedly, the development of arterial hypoxemia and structural changes peculiar to the "wet" lung could be averted. The results of the investigations demonstrate the possibility of HBO application for the prophylaxis and treatment of the syndrome.

[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.

[Sulfur and iron cycling bacteria in low-sulfate meromictic Lake Kuznechikha]. / Bakterii krugovorota sery i zheleza v nizkosul'fatnom meromikticheskom ozere Kuznechikha.

The hydrochemical characteristics, the composition of species and the localization of bacterial species involved in oxidation of sulfide and ferrous salts were studied in the meromictic Lake Kuznechikha with a low sulfate content in summer and in winter. The rate of bacterial sulfate reduction and the rates of bacterial and algal photosynthesis were determined using a radioisotope technique. The meromictic nature of the lake is due to the accumulation of ferrous salts (up to 212 mg/l Fe2+) in the monimolimnion. Free hydrogen sulfide is absent whereas the concentration of sulfides at the bottom reaches 16.5 mg/l. Hydrogen sulfide is produced mainly by sulfate reducing bacteria which are particularly active (0.35 mg of H2S per day) in the surface layer of reduced ooze. The photosynthetic green bacteria Chloronema giganteum, Chlorochromatium aggregatum, Chloroplana vacuolata and Pelochromatium roseum, the thiobacilli Thiobacillus intermedius and Th. trautweinii, the iron bacteria Ochrobium tectum and Arthrobacter sp. (Siderocapsa sp.) are found in the zone of chemocline at a depth of 6 m in the summer. The primary production of the phytoplankton in the summer is 160 mg C per 1 m2 per day while the production of the phototrophic bacteria is 100 mg C per 1 m2 per day. The fixation of carbon dioxide in the dark is performed mainly by heterotrophic bacteria. In the winter, the frontier of the anaerobic zone rises to the surface and photosynthetic bacteria are absent from it.

[Characteristics of sulfur bacteria from lakes of the Mari ASSR]. / Kharakteristika tionovykh bakterii ozer Mariiskoi ASSR

Five karst lakes were investigated in the Mari Autonomous Republic. The vertical distribution of thionic bacteria in water was correlated to the distribution and content of dissolved sulphides. The concentration of thionic bacteria was higher in more productive lakes. A symbiotic culture of thionic and denitrifying bacteria, but not Thiobacillus denitrificans, was isolated from water of these lakes.