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Applied Biochemistry and Microbiology (v.40, #6)
Biogenesis and Regulation of Biosynthesis of Erythromycins in Saccharopolyspora erythraea by V. A. Mironov; O. V. Sergienko; I. N. Nastasyak; V. N. Danilenko (pp. 531-541).
Data on the structure and stages of biosynthesis of erythromycins, relating to (1) successive addition of L-mycarose and D-desosamine to the lactones erythronolide B and mycarosyl-erythronolide B, respectively, and (2) biotransformation of erythromycin D to erythromycin A, are presented. Pathways of biosynthesis of L-mycarose, D-desosamine, and methylmalonyl-CoA and methylpropionyl-CoA precursors of erythronolide B are reviewed, along with the properties of genes coding the enzymes involved. Possible mechanisms of biochemical and gene regulation of erythromycin biosynthesis in Saccharopolyspora erythraea are discussed, including the role of factors ensuring predominant formation of the target product, erythromycin A.
Peroxidase Oxidation of Phenols by T. I. Davidenko; O. V. Oseychuk; O. V. Sevastyanov; I. I. Romanovskaya (pp. 542-546).
Partially purified preparations of horseradish peroxidase were able to catalyze the effective transformation of such phenol compounds as phenol, o-chlorophenol, 2,4,6-trichlorophenol, pentachlorophenol (giving rise to the formation of polymer products insoluble in water), resorcinol, and thymol (giving rise to the formation of low-molecular-weight products). The following conditions were found to be optimal for peroxidase oxidation and provide the maximum extent of elimination of phenol compounds: temperature, 15–25 and 25–30°C for phenol and chlorophenol compounds, respectively; molar ratio H2O2/phenol, 1 : 1; and transformation time, 1–3 h. Although effective transformation was observed within a broad range of pH, the efficiency of the process slightly increased at a pH from 6.0 to 7.5. It was suggested to carry out multiple peroxidase oxidations of phenols using partially purified peroxidase enclosed in a dialysis membrane bag placed into a solution of a phenol compound containing hydrogen peroxide.
Effects of Myostatin and Growth Factors on Cultured Human Cells by S. S. Shishkin; T. B. Krokhina; V. S. Akhunov; A. A. Makarov; V. O. Popov (pp. 547-550).
A dedicated cell-based biological test system was used to study specific effects of myostatin and other human growth factors on the proliferation of cultured myoblasts and fibroblasts. Myostatin inhibited myoblast growth without affecting human fibroblasts. In this test system, human growth hormone and insulin-like growth factor I acted as antagonists of myostatin, which indicates that these agents have a potential for blocking its effects in vivo.
The Carbohydrates of Submerged Mycelium of Xylotrophic Basidiomycetes by V. V. Shcherba; V. G. Babitskaya (pp. 551-554).
It was demonstrated that the total carbohydrate content in the submerged mycelium of xylotrophic basidiomycetes falls into the range of 34.66–57.57%. Free carbohydrates of the cell cytosol amounted to 14.52–28.64%; structural carbohydrates, to 20.14–32.70%. Qualitative composition of carbohydrates was studied, which allowed for attribution of structural polysaccharides to hetero- and homoglycans with β- and α-glycoside bonds.
Microbacterium oxydans, a Symbiont of Djungarian Hamster Which Displays Probiotic Properties by N. A. Ushakova; N. Yu. Feoktistova; T. V. Kolganova; T. P. Turova (pp. 555-559).
A resident microorganism (strain Xo-17) was isolated from secretions of the specific glandular structures at the corners of the mouth of Djungarian (Campbell's) hamster (Phodopus campbelli). According to cultures, morphological and physiological properties, phylogenetic analysis based on the sequence of the 16S rRNA gene, and analysis of the cell wall, the strain was assigned to the species Microbacterium oxydans. The isolated bacterium displayed probiotic properties when administered orally as a suspension of live cells for 20 days to Syrian (golden) hamster (Mesocricetus auratus), which manifested itself in increased overall body weight and weight of several organs and stimulation of both cell-mediated and humoral immunities.
Isolation of Cobalt-Resistant Strains of Propionic Acid Bacteria, Potent Producers of Vitamin B12 by E. A. Seidametova; M. R. Shakirzyanova; D. M. Ruzieva; T. G. Gulyamova (pp. 560-562).
A method of adaptation to cobalt nitrate at high concentrations allowed us to isolate 46 strains of propionic acid bacteria Propionibacterium acidipropionici, resistant to excessive amounts of Co2+ in the medium. Studies of these strains revealed cultures that were most potent in synthesizing vitamin B12. The yield of vitamin B12 was increased 3 times, compared to parent strains.
Purification of Soil from Oil Pollutants with the Use of Denitrifying Hydrocarbon-Oxidizing Microorganisms by E. R. Rakhimova; A. L. Osipova; S. K. Zaripova (pp. 563-567).
The efficiency of an oil-oxidizing microbial community in the bioremediation of oil-polluted soil was studied under laboratory conditions. A specific feature of the community was its ability to oxidize oil hydrocarbons under both aerobic and anoxic conditions. The degree of oil-hydrocarbon degradation in various bioremediation modes increased as follows: self-remediation (40%) < nitrate application (42%) < introduction of the denitrifying oil-oxidizing community (50%) < introduction of the denitrifying oil-oxidizing community plus nitrate application (60%). The intensification of bioremediation is related to the increase in the population of the hydrocarbon-oxidizing microorganisms, first of all, denitrifying ones, resulting from the introduction of the community.
Biodegradation of Phenanthrene by Pseudomonas Bacteria Bearing Rhizospheric Plasmids in Model Plant–Microbial Associations by T. O. Anokhina; V. V. Kochetkov; N. F. Zelenkova; V. V. Balakshina; A. M. Boronin (pp. 568-572).
The consumption of phenanthrene in soil by model plant–microbial associations including natural and transconjugant plasmid-bearing rhizospheric strains of Pseudomonas fluorescens and P. aureofaciens degrading polycyclic aromatic hydrocarbons was studied. It was shown that phytoremediation of soil polluted with phenanthrene in the rhizosphere of barley (Hordeum sativum L.) was inefficient in the absence of the degrading strains. Inoculation of barley seeds with both natural and transconjugant plasmid-bearing Pseudomonas strains able to degrade polycyclic aromatic hydrocarbons (PAH) protected plants from the phytotoxic action of phenanthrene and favored its degradation in soil. Rape (Brassica napus L.) was shown to be an appropriate sentinel plant, sensitive to phenanthrene, which can be used for testing the efficiency of phenanthrene degradation in soil. Biological testing with the use of sensitive rape plants can be applied for estimation of the efficiency of phyto/bioremediation of PAH-polluted soils.
Effects of Cytokinin Preparations on the Stability of the Photosynthetic Apparatus of Two Wheat Cultivars Experiencing Water Deficiency by O. F. Monakhova; I. I. Chernyad'ev (pp. 573-580).
Carboxylase activity of the key enzyme of carbon metabolism, ribulose-bisphosphate carboxylase/oxygenase (RuBisCO; EC 4.1.1.39), and phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31), as well as the intensity of carbon dioxide photosynthetic assimilation in young seedlings and adult leaves of the wheat Triticum aestivum L. cultivars Mironovskaya 808 (a more tolerant) and Lyutestsens758 (a less tolerant), were compared under conditions of progressive water deficiency. The water stress had more pronounced negative effects on all the studied characteristics of the photosynthetic apparatus of the cultivar Lyutestsens758. Its seedlings were more sensitive to water stress. Compounds with a cytokinin activity (6-benzylaminopurine, thidiazuron, kartolin 2, and kartolin 4) played a protective role, increasing the stability of the photosynthetic apparatus under conditions of water deficiency. Preparations of kartolins displayed the maximum protective effect.
Sugar Beet Photosynthesis under Conditions of Increasing Water Deficiency in Soil and Protective Effects of a Low-Molecular-Weight Alcohol by A. A. Kosobryukhov; K. Y. Bil'; J. N. Nishio (pp. 581-587).
The rate of CO2 gas exchange, transpiration, stomatal conductivity, and efficiency of the use of water were assessed in leaves of the sugar beet (Beta vulgaris var. Saccharifera (Alef) Krass.) sprayed with 40% methanol, against the background of increasing water deficiency in soil. A decrease in the negative impact of water deficiency in experimental plants was shown to be due to the larger stress-resistance of the photosynthetic apparatus, higher rate of photosynthesis, and more effective use of water.
Change in Lectin Specificity of Winter Wheat Seedlings in the Course of Infection with Mycoplasms by T. V. Trifonova; N. N. Maksyutova; O. A. Timofeeva; V. M. Chernov (pp. 588-591).
The activity of soluble lectins in leaves and roots of seedlings of winter wheat (Triticum aestivum L.) cultivar Mironovskaya 808 increased 1 day and 2 days, respectively, after infection with the mycoplasma Acholeplasma laidlawii 118. Analysis of acid-soluble proteins of wheat leaves by PAGE revealed the appearance of 22- and 20-kDa polypeptides, the disappearance of a 14-kDa polypeptide, and an increase in the content of polypeptides with molecular weights of 76, 48, 25, and 18 kDa. The 18-kDa polypeptide is a subunit of wheat germ agglutinin. A change in the activity of lectins may be a nonspecific response of plants to infection with the pathogen.
Theoretical Bases of Optimization of the Modes of Postharvest Treatment of Alkaloid-Synthesizing Medicinal Plants by M. Ya. Lovkova; G. N. Buzuk; S. M. Sokolova (pp. 592-598).
The method of disks in combination with thin-layer chromatography and spectrophotometry was used for a comparative evaluation of the efficiency of different methods of fixing and fermentation of medicinal plants (leaves). Medicinal plant species capable of synthesizing alkaloids of various structural types (isoquinoline derivatives including benzophenanthridines, bisbenzylisoquinoline, quaternary protoberberines, and aporphines, as well as steroid and diterpene alkaloids) were used. The methods of fixing and fermentation were shown to exert a substantial effect on both the qualitative and quantitative composition of alkaloids. This difference in the alkaloid composition was found to represent the superposition of three independent and, to a large extent, opposite processes: catabolism of alkaloids, interaction of alkaloids with each other, and resynthesis from primary precursors. The use of different methods of fixing and fermentation provides activation or inhibition of these processes, thereby making it possible to carry out target-oriented correction of the alkaloid composition of the medicinal plants studied.
Effect of Physicochemical Parameters on the Formation of Chitosan-Based Gels by A. V. Il'ina; V. P. Varlamov (pp. 599-602).
The possibility for forming physical gels based on Pchelozan (bee chitosan with a molecular weight of 230 kDa and an acetylation degree of 26–65%) has been demonstrated. Conditions for obtaining the gels (1% solution in 1% glycolic acid, 25°C, pH 5.5–7.5) were selected. The effects of (1) the concentration of the original solution, (2) the degree of acetylation of Pchelozan, and (3) the value of pH on the process of gel formation, were studied. The gels obtained may be classified with reversible toxotropic systems. These gels are stable for a long time when stored within a temperature range of 18–55°C. The gel with a degree of acetylation of 34% was characterized by irreversible syneresis.
Physicochemical Properties and Specific Structural Features of Protein–Lipid Composites of Increased Nutritive Value by V. V. Kolpakova; I. V. Martynova; L. I. Arabova; L. V. Chumikina (pp. 603-608).
Fractional and component compositions of protein–lipid composites with increased nutritive value (compared to the protein preparations from which they were produced) were studied based on solubility and electrophoretic behavior. Differences in the fractional compositions of proteins and the amounts of hydrogen, ionic, and hydrophobic bonds were found. It was demonstrated that the water-, salt-, and alkali-soluble fractions of proteins changed during the manufacturing of the composites with soybean and wheat bran flour; the water- and alkali-soluble fractions, with protein concentrate from bran. Heterogeneity of the compositions and specific conformational features of composite proteins resulting from disulfide bonds were found. It was demonstrated that, during the manufacturing of composites, proteins of soybean flour aggregated (with the involvement of disulfide bonds), whereas protein products from wheat bran disaggregated. Breaks of interchain (wheat) or intrachain (concentrate) disulphide bonds accompanied the disaggregation. Overall the properties and specific structural features of the protein–lipid composites studied depended on the nature of the protein (soybean or wheat), type of initial preparations (flour or concentrate), and method of their production (emulsifying or drying).
Binding by Cornstarch of Components of a Mixture of Volatile Organic Substances from Aqueous Solutions by T. A. Misharina; A. L. Samusenko; M. A. Kalinchenko (pp. 609-612).
Effects of the composition of a mixture of organic substances on the binding of individual components in aqueous dispersions of native and gelatinized cornstarches with different contents of amylose was studied by capillary gas chromatography. Binding was more active when alcohols were exposed to cornstarch as mixtures rather than individual compounds. In a multiple-component mixture, compounds belonging to distinct classes competed with each other for binding sites. Odorant binding by aqueous starch dispersions was more sensitive to the composition of the mixture and the nature of starch when studied in aqueous dispersions of native starches (compared to those of gelatinized starches).
Effect of Acid Hydrolysis of Oak Wood on Its Aroma-Forming Complex by A. F. Pisarnitsky; S. A. Klimov; E. V. Brazhnikova (pp. 613-616).
The effect of acid hydrolysis of English oak (Quercus robur L.) wood on its aroma-forming complex was studied. The contents of methanol, acetic and crotonic acids, and furfural increased considerably in the samples treated with hydrochloric acid. In the composition of minor compounds, aromatic hydrocarbons were synthesized de novo, whereas the contents of volatile phenols, such as vanillin, lilac aldehyde, and coniferaldehyde decreased; relative content of guaiacol and syringol elevated; and acetovanillon and propiovanillon were formed as well as products of degradation of hexoses—levoglucosenone, 1,4:3,6-dianhydroglucose, maltol, and 1,6-dianhydroglucopyran.