Chemistry. Ecology. Biotechnology

In the course of the work we examined two cultures; the first one has previously been tested for the sorption of zinc ions, and the second one has at the same time been selected; both were successful.

These two microorganisms developed most successfully in the meat-and-peptone agar medium, which had this composition: 1 L of infusion broth; 0,5% peptone; 0,25% yeastrel; 0,1% glucose and 2% agar-agar.

After the rejuvenescence and purification of the investigated cultures, their morphological description was made.

Morphological description of investigated cultures

The microorganisms were tested by the disk-diffusion method, and this method had shown their good resistance to the zinc and manganese impact. During this experiment we used heavy metal ion concentrations of: Mn2+ – 5, 50, 100, 200 mg/l; Zn2+ – 10, 50, 100, 200 mg/l. The obtained results give us hope for the possibility of using these microorganism cultures for absorption of the zinc and manganese ions from solutions.

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УДК 579.222.4

P.V. Velieva, N.B. Remezovskaya, A.Yu. Maksimov

ENANTIOSELECTIVE BIOTRANSFORMATION DERIVATIVES OF BENZOXAZINE AND QUINOLINE

Perm National Research Polytechnic University

Currently, much attention is paid to the study of enantioselective biocatalytic synthesis of practically important organic compounds. In particular, the current trend is producing intermediates of fluoroquinolones synthesis. Fluoroquinolones are a modern class of antibacterial drugs. Fluoroquinolones are molecules created by the chemical synthesis; they may be, with further chemical modification of the substituent structure, transformed to compounds with improved pharmacological and chemotherapeutic characteristics. The best-known fluoroquinolones are levofloxacin, prulifloxacin, moxifloxacin, ciprofloxacin. Fluoroquinolones are extremely active against gram-positive cocci and anaerobic pathogens. In recent years, the fluoroquinolones are used for treating tuberculosis on a large scale.

The application of microorganisms as carriers of the active multienzyme systems capable of transferring exogenous organic compounds to various wholesome products is based on the fact that they can carry out major transformations in one stage, while the process of synthesis takes 20 chemical stages for it. The unique specificity and stereospecificity of the enzymes influence, the possibility of carrying out the processes in «soft» conditions, the high speed of the reaction behaviour, while the catalyst quantity is negligible, and, finally, the near absence of ADR’s – all these features makes the processes of enantioselective biotransformation attractive and far-reaching from the technological point of view.

The purpose of this work is to study the possibility of using enzyme systems from a number of soil microorganisms in the processes of enantioselective biotransformation of benzoxazine and quinoline derivatives as potential intermediates of the fluoroquinolones synthesis.

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As a result of the conducted research, the influence on growth of bacterial cultures made by the transforming substratum has been defined. The best possible growth phases, in which cells are subsequently selected for biotransformation, have been revealed for each strain.

Biotransformation of benzoxazine and quinoline derivatives was carried out for 7 days. According to the preliminary results, efficiency and stereoselectivity of conversion depend on the structure of a substratum.

УДК 541.183.12

A.U. Druk, L.S. Pan

THE SYNTHESIS OF EFFECTIVE BIOSORBENTS TO CLEAN DRINKING WATER FROM CESIUM

Perm National Research Polytechnic University

The increase of pollution of natural water with radioelements adds to the importance of water purification problem. Emission of radioactive elements into the environment, including cesium, is a result of nuclear weapon tests and accidents at nuclear power plants.

Cesium-137 that is released into the atmosphere is a long-term source of soil, groundwater and wastewater contamination. One of the methods to extract Cesium from water is usage of biosorbents with sufficient adsorption capacity and high cesium ions selectivity.

Hexacyanoferrates of transition metals have better sorption properties to cesium than other sorption materials. Also hexacyanoferrates are immune to wide pH range, high salt concentrations, and ionizing radiation. Furthermore, they exhibit a high selectivity towards cesium ions. However, using these sorbents for cleaning drinking water, milk and other liquid food products requires creation of non-toxic material with biological safety. Therefore, as the biomass for sorbent the Black Sea algae, brown algae Zostera Marina in particular, was chosen. It is proved

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that the alginic acid (which algae contains) can associate with metals and radioisotopes into insoluble compounds.

With the purpose to increase the cesium ion selectivity of natural materials and improve the sorption properties the iron hexacyanoferrate was administered in algae matrix. Choice of iron hexacyanoferrate as an active component of the sorbent is explained by the fact that it is biologically safe and a “Ferrocin” drug is manufactured on its base. It is known that HCF-Fe has a high adsorption capacity and cesium ions selectivity. However, the low mechanical durability and peptization ability makes it impossible to use.

To reduce the disaggregation of sludge and formation of more crystalline structure of HCF-Fe in its composition Mn2 + ions were introduced as a dopant. This ion was chosen because of its isoelectric structure, tendency to coordinate with the CN group (c.n. = 6), as well as its nutrient properties.

The sorbent was obtained by sequential processing of the algae with solutions of iron (III) salt, manganese chloride (II) and potassium hexacyanoferrate (II). The percentage of iron and manganese salts varied from 5 to 30 (% by weight). To eliminate coprecipitation of iron hydroxide, the sorbent was washed with hydrochloric acid on the final step. As a result, four samples of sorbent with the following composition HCFphases were obtained:

1)H1.6 K0.31 Mn0.036 Fe0.68 [Fe(CN)6],

2)H1.6 K0.31 Mn0.074 Fe0.63 [Fe(CN)6],

3)H1.67 K0.31 Mn0.11 Fe0.60 [Fe(CN)6],

4)H1.71 K0.33 Mn0.14 Fe0.56 [Fe(CN)6].

It has been shown that the introduction of doping manganese ion in the iron hexacyanoferrate in small quantities significantly reduces peptization of the sediment and increases the mechanical strength of the sorbent. The X-ray diffraction analysis of these samples showed that the partial replacement of the ion Fe+ 3 (Ri = 0.67 Aº) with Mn+2 ions that have a larger radius (Ri = 0.91 Aº) does not change the crystal sorbent cell symmetry and the formation of new crystalline phases, but is accompanied by a change of the main diffraction maxima intensity, which may indicate a change in the structure defects.

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The sorption properties of the materials and the selectivity towards cesium ions were studied. The biological safety of sorbents and the possibility of their use for the purification of drinking water by cesium ions were proved.

УДК 579.222.2

N.A. Pechenitsina, L.G. Cheraneva

INFLUENCE OF ACIDITHIOBACILLUS FERROOXIDANS

AND Fe(III) IONS ON BIOCORROSION OF CHEMICAL

CURRENT SOURCES IN THE PROCESS OF THEIR

RECYCLING

Perm National Research Polytechnic University

Now about 15% of the Russian territory is in critical condition by the environmental indicators. This is mainly true for the central part of the country, such regions as Siberia and Ural. The sources of anthropogenic soil contamination are wasteproducts of industrial and communal activities of humans. They are, for example, electrochemical cells (ECCs), which include a wide range of harmful elements (lead, zinc, cadmium, manganese, etc). The system of the ECC recycling is underdeveloped in Russia, and people often throw away small-sized batteries just with the household waste. For instance, a biological half-life of the zinc in the soil is up to 500 years, while for the lead it takes up even to several thousand years to be halfway removed, which actually means that the hazardous substances will probably be still able to get into the human body with food and water for many years in the future. It has a negative impact on the human health, because lead can cause a nervous breakdown and osseous lesion, cadmium harms lungs, nickel causes dermatitis and zinc affects

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kidneys. Thus, processing and recycling of the ECCs are really important processes for the modern technologies.

The aim of our research is to find the method of wasted ECC recycling, which is based on bio-corrosion processes. We used Zn-Mn batteries, as they are the most widespread ECCs. The Acidithiobacillus ferrooxidans, which belong to the group of thionic bacteria, were selected for the oxidation of the batteries. These microorganisms are often found in the acid mine waters; they may be used as cheap resource in the recycling process. A. Ferrooxidans were isolated from the acid (pH = 2.5) wastewaters of Kalinin coalmine in the town of Gubakha on a nutrient medium of Silverman and Lyundgren (9K).

The influence of wide range of factors was examined for determining the technological parameters of ECC decomposition process. For example, the electrochemical corrosion of the battery’s ironwork depends on the measure of the medium acidity, so does the growth of microorganisms. The experiment was conducted along with the solution pH variation within the interval of 1.4-3.1. According to the Pourbaix diagram, if pH>3, a Fe(OH)3 precipitate will be separated, i.e. the oxidant ions Fe+3 which are formed from the Fe+2 ions as a result of the bacterial activity are lost. Even though the creation of the highly acidic medium would actually be beneficial for dissolving the ECC ironwork, the bacteria will develop to a lesser degree in this environment. The medium with pH of 2.6-3.1 would be optimal for microbial growth because the optical density of the solutions would be greater in these conditions, i.e. the content of Fe+3 ions is of greater level there. We also found that the quantity of microorganisms measured at the Gorjaev's count chamber (Colony Forming Unit = 1.2·106 – 1.3·106) increases there. The influence of such factors as the crushing and mixing of ECC solutions on a shaker (145 rpm) on the process of dissolution of different Zn-Mn type batteries in the form of a disk is represented in the table.

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The influence of kinetic parameters on the ECC bio-corrosion process

The table shows that if we add the same amount of the A. Ferrooxidans in solutions, on a per-unit basis, the bio-corrosion indicators are much better than of small ECC. Plus, the crushing only slightly increases the degree of ῶ dissolution and corrosion rate in Km±. However, a significant difference is observed, if the solutions are mixed. In this case, a high degree of ECC dissolution (more than 80%) and almost doubled index of their corrosion can be achieved with continuous updating of the reagents on the surface.

УДК 577.121.2

A.A. Rukavitsyna, A.V. Bazhutin, L.D. Asnin

ENANTIOSELECTIVE BIODEGRADATION

OF PHENYLALANINE BY VARIOUS MICROORGANISMS

Perm National Research Polytechnic University

Being chiral compounds, amino acids can exist in two optical isomers, L- and D-enantiomers. For a long time it has been considered that all living organisms contain and use only L-amino acids in their vital activity. But, subsequently, it has been shown that D-amino acids are included in some proteins and can be metabolized by microorganisms*.

* Horonenkova S.V., Tishkov V.I. D-amino acid oxidase: physiological role and usage // Biological chemistry reviews. – 2008. – T. 48. – P. 359–376.

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The figuring out of the differences in the microbiological transformation of amino acids optical antipodes is an interesting problem that is important both for understanding of a physiological role of D-enantio- mers and for creation of the biochemical methods of the D-containing peptides synthesis.

In this study, the biodegradation of the phenylalanine enantiomers by the Rhodococcus erytropolis, Pseudomonas sp., Bacillus subtilis bacteria was investigated. The experiments were conducted at a temperature of 29оС in the Raymond nutrient medium, at pH of 6.5, 6.9, and 7.5, and also in a medium that contains glucose as a second nutrient source. The analysis of the substrate concentration was carried out using the Shimadzu LC-20ADXR chromatograph with an UV-detector. The chromatographic column was the ShimPack XR-ODS II thermostated at the temperature of 25оС. An acetate buffer solution (pH = 5.2) prepared in a mixed water-methanol (60:40) solvent was used as a mobile phase.

It was found that all studied strains of microorganisms could utilize both kinds of enantiomers. In this case, the activity of bacteria is much lower for D-, than L-phenylalanine destruction. The transformation degree may reach ca. 20% for D-phenylalanine and 30% for L-phenyla- lanine. In both cases the sequence of the microorganism activity is as follows: Pseudomonas > R. erytropolis > B. subtilis. The chromatogrames show that the composition of the degrading products is different for L- and D-enantiomers; a greater diversity in the products is observed for Rhodococcus. When glucose is added in the growth medium, the transformation degree usually becomes lower. The impact of pH value is negligible in the studied range.

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УДК 544.034

N.A. Klimov, D.A. Kazakov, Y.E. Tarakanova, V.V. Volkhin

INTENSIFICATION OF OXALIC ACID MINERALIZATION BY COMBINATION OF CATALYTIC OZONATION

AND BIODEGRADATION

Perm National Research Polytechnic University

Oxalic acid (OA) is widely used in the chemical, textile and leather industries, as well as in the detergent production. The content of OA in the bodies of waters, in accordance with TLV should not exceed 0.5 mg/l, so its entry into the environment should be prevented. Biodegradation of OA, particularly at higher concentrations, is very slow because of its strong acidic properties. OA biodegradation progresses really slowly because of its rather strong acidic properties and deficient energy for the microorganisms, especially on its elevated concentrations. It may be assumed that the speed of OA biodegradation can be increased by maintaining the optimal level of its concentration in the reaction medium and by application of the biocatalyst based on immobilized microorganisms' cells - the decomposers. To reduce the concentration of OA in aqueous medium to the level that is optimal for the biodegradation, chemical decomposing methods may be used. The most common method is ozonation. However, the OA mineralization is slow under the ozonation process, which makes it currently important to develop effective catalysts for this process. The catalysts based on the finely divided carbon materials show high activity against OA mineralization under ozonation. But the choice of carbon materials with optimal catalytic properties in regard to OA mineralization is difficult because of the lack of information about the relationship of their physical-chemical properties and catalytic activity. Thus, the aim of the study is to know how to increase the speed of OA mineralization by the combination of oxidation processes, using biocatalyst and catalytic ozonation in the presence of carbon materials. The research objectives are:

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1.to isolate the microorganisms decomposing OA;

2.to synthesize a biocatalyst of the OA mineralization based on the immobilized microorganisms (the decomposers); to study the activity of the derived biocatalyst;

3.to determine the macrokinetic mode of the OA mineralization process under the ozonation;

4.to synthesize catalysts of the OA mineralization by the carbonization and chemical activization of various precursors of carbon materials;

5.to study the effect made by the obtained catalysts on the OA mineralization rate under the ozonation;

6.to study the OA mineralization process which combines its preliminary ozonic-catalytical oxidation made up to the level optimal for the biodegradation with the destruction in the presence of the biocatalyst.

Microorganisms which are degrading OA were isolated from the “LUKOIL-Permnefteorgsintez” sewage sludge. It was found out that the isolated microorganism culture is one of the micromycetes and has an evolved mycelium and sporangia.

The influence of OA on the ozone dissolution speed in the aquatic phase was observed and the macroscopic speed of the OA oxidation by the ozone was determined; it was shown that the OA mineralization process is characterized by transient mode, i.e. it is limited simultaneously by the ozone mass transfer within the system “gasliquid” and by the speed of its relationship with OA. Thus, the macroscopic the OA mineralization rate may be increased by using the catalysts. On the basis of various precursors of carbon materials (they are: agar - agar (sample 1), birch sawdust (sample 2), excess activated sludge from the “LUKOIL-Permnefteorgsintez” sewage (sample 3)) the catalysts for the OA mineralization were obtained by means of the carbonization with chemical activation. The values of the effective

rate constants of the OA mineralization (keff) rate and the rate of ozone absorption by aqueous medium (V) in the presence of the derived catalysts are presented in the table.

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