[Effect of polycyclic aromatic hydrocarbons on laccase production by white rot fungus Pleurotus ostreatus D1].

The effect of polycyclic aromatic hydrocarbons (PAHs) on the dynamics of laccase production by the fungus Pleurotus ostreatus D1 under conditions of submerged cultivation on Kirk's medium has been studied. It has been shown that phenanthrene, fluoranthene, pyrene, and chrysene actively induce this enzyme, whereas fluorene and anthrecene had a smaller effect. Addition of Mn2+ ions to cultivation medium elevates the laccase activity twofold and more in the presence of all the studied PAHs. Electrophoresis under nondenaturing conditions demonstrates induction of additional laccase species by xenobiotics. Ligninolytic peroxidase activities are undetectable under the conditions used.

[Comparison of efficiencies of oil-oxidizing Dietzia maris strain and stimulation of natural microbial communities in remediation of polluted soil].

Two approaches to bioremediation of oil-polluted soils are compared: use of active degrader strain Dietzia maris AM3 and stimulation of natural microflora. Introduction of D. maris AM3 to soil freshly polluted with oil accelerated its remediation twofold within the first month in comparison with the stimulation. After three months, the purification degrees were approximately equal. By the end of bioremediation, the soil with the introduced strain had higher dehydrogenase and catalase activities. In soil with multiyear pollution, introduced strain D. maris AM3 did not affect the rate of oil product degradation, and no significant differences between the two bioremediation methods were detected in purification degree and biological activity of soil after three months.

[Degradation of hydrocarbons and their derivatives by a microbial association based on Canadian pondweed].

The degrading action of an aquatic plant-microbial association on the base of Canadian pondweed (Elodea canadensis) and its components (sterilized plant and two periphytonic strains, Pseudomonas fluorescens E1-2.1 and Brevundimonas diminuta E1-3.1) on crude oil, the water-soluble crude oil fraction, and individual test compounds (phenol, toluene, benzene, decalin, and naphthalene) was studied. It was found that the native association had a wider range and higher degree of degrading activity than individual species. Bacterial strains were significantly more active only towards naphthalene. The ability of the sterilized plant to degrade crude oil and phenol was no less than that of microorganisms and much more for toluene. Enzymatic activity towards the pollutants studied was found in E. canadensis exudates and buffer extracts of its cells.

[Bioremediation of oil-polluted soil with an association including the fungus Pleurotus ostreatus and soil microflora].

The possibility of application of the Pleurotus ostreatus D1-soil microflora to bioremediation of oil-polluted soils was studied. The fungus degraded mainly the aromatic fraction, whereas soil microflora intensely degraded paraffin and naphthene oil fractions. Introduction of the fungus Pleurotus ostreatus D to soil induces degradation of a wider range of oil hydrocarbons. It is reasonable to further investigate the discovered phenomenon in order to improve procedures of remediation of oil-polluted soils.

[Yellow laccase from the fungus Pleurotus ostreatus D1: purification and characterization].

Yellow laccase was isolated from a solid-phase culture of the fungus Pleurotus ostreatus D1 and characterized. It is a copper-containing enzyme with molecular weight 64 kDa. Its absorption spectrum lacks the maximum at 610 nm, characteristic of fungal laccases and corresponding to type I copper atom. The optimum pH values for the enzyme were determined. They proved to be: 7.0 for syringaldazine, 8.0 for pyrocatechol, and 4.0 for 2,2'-azine-bis-(3-ethylbenzothiazoline-6-sulfonate and 2,6-dimethoxyphenol. Kinetic parameters (Km and Vmax) for oxidation of these substrates were determined. The effect of inhibitors (SDS, 2-mercaptoethanol, and EDTA) on the activity of the enzyme was studied. It was shown that yellow laccase from Pleurotus ostreatus D1 oxidized anthracene to anthraquinone by 95% without any mediator.

[Development of an oil-degrading biopreparation by activation of aboriginal hydrocarbon-oxidizing microflora].

A method of activation of aboriginal hydrocarbon-oxidizing microorganisms for remediation of soil and water basins polluted with oil products was developed. The optimum composition of activating additives was found (g/l): mineral components, 10.0; oil, 5.0; and a synthetic detergent, 0.2. The resulting biopreparations increased the degree of purification by factors of 4-8 in soil and 18-24 in water when applied at a concentration of 10(7) cells/g(ml).

[Oil-oxidizing potential of associative rhizobacteria of the genus Azospirillum].

The oil-oxidizing potential of associative rhizobacteria of the genus Azospirillum was studied under laboratory conditions. After screening, A. brasilense strain SR80 was chosen for further investigation. The strain was capable of degrading 56.5% of crude oil (added in a concentration of 1%) over 14 days in a medium containing malate as an additional source of carbon and energy. Studies of associative properties showed that the strain had positive chemotaxis to wheat root exudates, colonized wheat roots, and produced indolyl-3-acetic acid. The synthesis of indolyl-3-acetic acid was not inhibited by oil. Under hydroponic conditions, crude oil stimulated growth of A. brasilense SR80, which promoted development of the wheat root system in the presence of oil and enhanced the level of oil degradation by the plant-microbial association.

[Efficiency of alfalfa and reed in the phytoremediation of hydrocarbon polluted soil]. / Ispol'zovanie liutserny i trostnika dlia fitoremidiatsii zagriaznennogo uglevodorodami grunta.

The efficacy of plants as means of decontaminating hydrocarbon-polluted soil has been studied. Ditch reed (Phragmites australis) and alfalfa (Medicago sativa) markedly intensified processes of pollutant destruction, the effect being particularly pronounced in the case of polycyclic aromatic hydrocarbons (PAHs). Comparative analysis of microflora in soils (including those devoid of plants and rhizosphere) demonstrated that, in addition to preventing the pollutant-induced decrease in the amount of heterotrophic microorganisms, the plants stimulated their development, significantly increasing the population of destructors. Effects of plants on major physiological groups of soil microorganisms under conditions of pollution were ambiguous. The rhizosphere consortium of alfalfa was less susceptible to effects of pollutants than that of reed.

[Degradation of mineral oil by Acinetobacter calcoaceticus strain]. / Degradatsiia mineral'nogo masla shtammom Acinetobacter calcoaceticus.

The Acinetobacter calcoaceticus strain TM-31 has been isolated from a microbial assemblage of a pilot plant purifying waste water polluted with mineral oil. This strain is capable of efficient degradation of components of mineral oil (alkanes, isoalkanes, and alkyl residues of the naphthene and arene fraction. The strain bears stably inherited plasmids of sizes 120, 9, and 8 kb, which can be transferred into plasmid-free cells of the parental strain and into bacteria of the genus Pseudomonas and ensure the degradation of hexadecane and mineral oil.

[Degradation of mineral oils by a selected microbial association]. / Degradatsiia mineral'nykh masel selektsionirovannoi mikrobnoi assotsiatsiei.

A series of microbial associations capable of degrading various petroleum oils, emulsols, and crude oil were obtained by selection during periodic or continuous cultivation. The formation of these associations and oil-product degradation occurred most efficiently during aerobic flow cultivation. Under these conditions, oils were degraded by 92% on average. The microbial degradation of a petroleum oil depended on its brand, concentration, emulsification, and aeration.

[Strain of Pseudomonas aeruginosa--producer of bioPAV]. / Shtamm Pseudomonas aeruginosa--produtsent bioPAV.

A Pseudomonas aeruginosa strain producing an extracellular surfactant (biosurfactant) was isolated. The growth of this strain, referred to as 50.3, on a mineral glycerol-containing medium produces an emulsifying activity (60%) and decreases the surface tension of the culture liquid by a factor of 2.8 (to 25 mN/m). The optimum conditions for its growth and production of biosurfactants: intense aeration, pH 7.0-8.0, and the presence of Mg2+. The optimum biosurfactant properties were achieved when glucose was used as the only source of carbon and energy and NH4Cl was used as a source of nitrogen. The biosurfactant was isolated from the culture liquid by extraction and precipitation.

[Respiratory activity of bacteria Acinetobacter calcoaceticus TM-31 during assimilation of alkane hydrocarbons]. / Respiratornaia aktivnost' bakterii Acinetobacter calcoaceticus TM-31 pri assimiliatsii alkanovykh uglevodorodov.

The respiratory activity of Acinetobacter calcoaceticus TM-31 with resect to alkane hydrocarbons was studied. The dynamics of oxygen consumption by the cells while assimilating n-hexadecane was assayed by a modified technique using an oxygen electrode. The dependence of cell respiratory activity on the amount of n-hexadecane within the concentration range of 0.03-0.66% was determined. It was demonstrated that the cells also displayed respiratory activity towards other medium-chain n-alkanes: hexane, octane, decane, tridecane, and heptadecane. Thus, we demonstrated the possibility of determining alkanes by measuring the respiratory activities of microorganisms.

[Study of microbial degradation of nonionic surface-active agents in designing technologies for purifying waste water]. / Izuchenie protsessov mikrobnoi degradatsii neionogennykh poverkhnostno-aktivnykh veshchestv pri razrabotke tekhnologii ochistki stochnykh vod.

Studies of degradation of non-ionic surfactants (NISA) in a model purification plant of an original design demonstrated an high rate and depth of degradation processes compared with periodic cultivation of free or immobilized degrading strains. A virtually complete primary degradation (99-99.5%), with destruction of the oxyethyl moiety of the molecule, was observed. In addition, NISA molecules were degraded to a greater extent, including considerable degradation of the hydrocarbon radical, partial degradation of aromatic structures in Neonol, and utilization of biologically "unyielding" fractions of commercial NISA preparations: polyethylene glycol (PEG) and long-chain fractions of polymer homologues.

[Degradation of syntanol DS-10 by bacteria immobilized in polysaccharide gels]. / Utilizatsiia sintanola DS-10 bakteriiami-destruktorami, vkliuchennymi v polisakharidnye geli.

Degradative capability of bacterium Pseudomonas putida immobilized in polysaccharide (agar-agar or furcellarane) gels towards a nonionic surfactant sintanol DS-10 was studied. The immobilized cells were shown to retain their ability to degrade the substrate in the model experiments as well as in the real waste water. The substrate was degraded after adsorption to the carrier beads.