Vol 88, No 13 (2018)

The influence of aryl-substituted xylose derivatives on fermentation of nonmedical antifungal antibiotic imbricin was evaluated. It was shown that, though unsuitable as additional carbohydrate sources in the growth medium for microorganism-producer development, these compounds can be used as biosynthesis regulators stimulating the antibiotic production. Biological tests showed that the aryl-substituted xylose derivatives possess antibacterial activity and, when added to the initial fermentation medium, protect the imbricin fermentation process against possible contamination.

Substituent effect on the rate of biochemical transformation of substituted anilines in natural water has been studied. The process can be described by the Hammett equation. The direction of polar substituent effect suggests participation of the amino group in the rate-limiting step.

Pedochemical characteristics such as acid–base properties, state of organic matter, and composition of the soil adsorption complex (SAC) in the forests surrounding large industrial enterprises in the Baikal region have been studied. The contaminated soils have been found to exhibit considerably increased alkalinity [pH (H₂O) 7.6–8.5], reduced rate of mineralization of organic matter to humic compounds (2.5-fold increased C/N ratio and 2–6-fold increased CO₂ emission), and disturbed ratio of exchanging Ca²⁺, Mg²⁺, K⁺, and Na⁺ ions. A grading scale of soils in the Baikal region with respect to their ecological state has been developed on the basis of pedochemical characteristics.

Sources of environmental pollution by polycyclic aromatic hydrocarbons have been analyzed, and their optimal molar ratios suitable for the identification of their origin have been determined. Polycyclic aromatic hydrocarbons have been shown to possess indicator properties which make it possible to distinguish compounds of biogenic, petrogenic, and pyrogenic origins.

Aluminum concentrations in river waters of the mountain and foothill zones of the Central Caucasus were studied. The concentrations were measured by atomic absorption spectrometry. The aluminum concentrations in 87% of samples were above the maximum permissible concentrations (MPCs) for fisheries and the aluminum concentrations in 20% of samples were above the MPCs for drinking water. The highest aluminum concentrations were found in the river waters of the modern and ancient volcanism regions. A number of factors contribute to the bioavailability of aluminum in these rivers, and this may pose threat for living organisms, including humans.

The composition of metabolites of cyanobacteria cultures of the Astrakhan region has been studied by thin-layer chromatography, high-performance thin layer chromatography, and high-performance liquid chromatography. Thin layer chromatography analysis of the cyanobacteria metabolites has shown the best separation and quality of chromatographic zones in seven systems: chloroform, ethanol: acetic acid (1: 1), butanol, ethanol: water (1: 9), butanol: acetic acid: water (4: 1: 5), ethanol: water (9: 1), and butanol: acetic acid: water (4: 1: 5). The flavonoid quercetin has been detected in an aqueous–alcoholic extract by high -performance thin-layer chromatography. The high-performance liquid chromatography has allowed identification of aspartic, isomonic, lactic, and fumaric acids in the cyanobacteria metabolites. Antioxidant activity of aqueous and aqueous-alcoholic extracts of the Phormidium ramosum B.-Peters IPPAS B-2022 culture has been detected.

Results of the hydrochemical and sanitary microbiological studies of water in the coastal part of the Neva Bay in the Lomonosov District are presented. The observations of the state of surface waters are used to assess the anthropogenic impact on the environment. The water pollution index (WPI) is calculated.

The results of long-term research on the concentrations and coexisting manganese species in different-type water bodies of the Ukraine (rivers, reservoirs, estuaries, small lakes, and ponds) are summarized. High manganese concentrations are characteristic, as a rule, of the hypolimnion zone. The ratio of particulate and dissolved manganese species depends on the type of the water body and their transformation processes in this specific water body. The concentrations of dissolved manganese in reservoirs, lakes, and estuaries much increase in conditions of oxygen deficiency and anaerobic deep water. The weight fraction of labile forms is large, which is characteristic of manganese. In water bodies rich in humic substances a large fraction of dissolved manganese is incorporated in complex compounds. In small lake and pond systems, carbohydrates play an essential role in binding of Mn(II).

A method for the synthesis of (2S)-(+)-hexan-2-ol, the precursor of a series of drugs, by the enantioselective bioreduction of the prochiral hexan-2-one is proposed. The use of various exogenous reducing agents (isopropanol, ethanol, and glucose) for increasing the yield of the target (2S)-(+)-hexan-2-ol and the enantioselectivity of the bioreduction of hexane-2-one are investigated.

Herein we have assessed the state of soil bacterial communities at different levels of pollution with oil. The dependences of the change in the total abundance of non-spore-forming bacteria and bacilli in sodpodzolic soil and typical chernozem have been obtained. The species composition of microorganisms in polluted soils has been assessed. The dynamics of the changes in the structure of bacterial communities with time after single oil pollution has been traced. Several microbiological parameters which can be used as diagnostic tools in case of oil pollution of soil have been found.

Using the laboratory modeling method, it has been shown that the enzymatic Michaelis–Menten kinetics equation provides a reasonable description of nitrification process in natural waters. The reaction has the first rate order with respect to the enzyme and pseudo zero order with respect to the substrate (ammonium ion) in a large excess of the latter.

The results of hydrochemical and hydrobiological studies performed in October 2009, July 2010, and July 2016 in the Blagopoluchiya Bay of Solovetsky Island are given. The concentrations of petroleum hydrocarbons, phenols, oxygen, nutrients, and chlorophyll a, BOD₅, and qualitative and quantitative compositions of phytoplankton have been determined. The integrated pollution and eutrophication indices have been calculated, and the up-to-date water quality in the Blagopoluchiya Bay has been assessed; increased level of seawater pollution has been revealed. The obtained results are important from both scientific and practical viewpoints with respect to environmental safety of the community facilities in the study region.

Biological experiments with nonmedical antibiotics lucensomycin, tetramycins A and B, aureofungins A and B, and antimycin A were carried out. These antibiotics were found to be environmentally friendly preparations possessing antifungal, antibacterial, and insecticidal activities. The prospects for their application for plant protection against diseases and harmful arthropods and for increasing the agricultural crop yield were shown.

The results of studies of the vanadium content and its coexisting forms in surface water bodies of various regions have been summarized. It has been shown that vanadium concentration in uncontaminated water bodies and rivers does not exceed several μg/L, whereas its concentration in water bodies which are subject to anthropogenic influence or located in the regions of volcanic activity reaches tens to hundreds of μg/L. The ratio of the suspended and dissolved forms of vanadium has been considered. The dissolved form of vanadium generally predominates in water bodies, whereas its migration as a constituent of suspended substances is characteristic of rivers, especially during the spring period. The studies of dissolved vanadium compounds concerning the ratio of its oxidized and reduced forms as well as complexation with dissolved organic matter have been discussed. It has been shown that V(V) dominates in the form of the H₂VO₄^– anion as the most stable form under oxidative conditions of surface waters. Several studies have noted the predominance of V(IV) in the form of oxocation VO²⁺, although it is known as unstable in the natural aquatic environment and is rapidly oxidized to V(V). This process is decelerated in the presence of humic substances which exhibit reducing properties. Anionic, cationic and neutral complexes of vanadium with organic ligands are known. Humic substances play a major part in the complexation as established for certain water bodies of Ukraine. The results of studies on the molecular weight distribution of vanadium complex compounds have been also considered.