Ivan Kushkevych

Preparation and Biological Properties of Ring-Substituted Naphthalene-1-Carboxanilides

In this study, a series of twenty-two ring-substituted naphthalene-1-carboxanilides were prepared and characterized. Primary in vitro screening of the synthesized carboxanilides was performed against Mycobacterium avium subsp. paratuberculosis. N-(2-Methoxyphenyl)naphthalene-1-carboxamide, N-(3-methoxy-phenyl)naphthalene-1-carboxamide, N-(3-methylphenyl)naphthalene-1-carboxamide, N-(4-methylphenyl)naphthalene-1-carboxamide and N-(3-fluorophenyl)naphthalene-1-carboxamide showed against M. avium subsp. paratuberculosis two-fold higher activity than rifampicin and three-fold higher activity than ciprofloxacin. The most effective antimycobacterial compounds demonstrated insignificant toxicity against the human monocytic leukemia THP-1 cell line. The testing of biological activity of the compounds was completed with the study of photosynthetic electron transport (PET) inhibition in isolated spinach (Spinacia oleracea L.) chloroplasts. The PET-inhibiting activity expressed by IC50 value of the most active compound N-[4-(trifluoromethyl)phenyl]naphthalene-1-carboxamide was 59 μmol/L. The structure-activity relationships are discussed.

Production of biogas: relationship between methanogenic and sulfate-reducing microorganisms

Abstract The production of high-quality methane depends on many factors, including temperature, pH, substrate, composition and relationship of the microorganisms. The qualitative and quantitative composition of methanogenic and sulfate-reducing microorganisms and their relationship in the experimental bioreactors has never been studied. The aim of this research was to characterize, for the first time, the diversity of the methanogenic microorganisms and sulfate-reducing bacteria, and study their relationship and biogas production in experimental bioreactors. Amplification of 16S rRNA gene fragments was carried out. Purified amplicons were paired-end sequenced on an Illumina Mi-Seq platform. The dominant morphotypes of these microorganisms in the bioreactor were homologous (99%) by the sequences of 16S rRNA gene to the Methanosarcina, Thermogymnomonas, Methanoculleus genera and Archaeon deposited in GenBank. Three dominant genera of sulfate-reducing bacteria, Desulfomicrobium, Desulfobulbus and Desulfovibrio, were detected in the bioreactor. The phylogenetic trees showing their genetic relationship were constructed. The diversity and number of the genera, production of methane, hydrogen sulfide and hydrogen in the bioreactor was investigated. This research is important for understanding the relationship between methanogenic microbial populations and other bacterial physiological groups, their substrate competition and, in turn, can be helpful for controlling methanogenesis in bioreactors.

Activity of ring-substituted 8-hydroxyquinoline-2-carboxanilides against intestinal sulfate-reducing bacteria Desulfovibrio piger

Desulfovibrio genus is dominant among sulfate-reducing bacteria (SRB) in the large intestine of healthy people and animals. It is mostly isolated from patients with inflammatory bowel disease (IBD) and can be involved in the disease initiation. Primary in vitro screening of 8-hydroxyquinoline-2-carboxanilides was performed against Desulfovibrio piger Vib-7 representing SRB. The most effective compounds with MIC90/MBC values in the range of 17–23 µM/20–23 µM, respectively, were substituted in C’(3) by CF3, OCH3, CH3 and in C’(4) by CF3. Their activity was twofold higher than that of ciprofloxacin. These compounds did not express any significant cytotoxic effect on THP-1 cells up to the tested concentration of 30 µM. The antibacterial efficacy of the most active C’(3)-substituted compounds practically did not change with increasing compound lipophilicity, indicating that this position of substitution is favorable for significant antimicrobial effect, while the antibacterial activity of most of C’(2) and C’(4)-substituted derivatives decreased linearly with increasing compound lipophilicity. In addition, the dependence of activity on electronic Hammett’s σ parameter of the substituent R was quasi-parabolic for the most effective C’(3)-substituted compounds.

The diversity of sulfate-reducing bacteria in the seven bioreactors

Anaerobic technology has a wide scope of application in different areas such as manufacturing, food industry, and agriculture. Nowadays, it is mainly used to produce electrical and thermal energy from crop processing, solid waste treatment or wastewater treatment. More intensively, trend nowadays is usage of this technology biodegradable and biomass waste processing and biomethane or hydrogen production. In this paper, the diversities of sulfate-reducing bacteria (SRB) under different imputed raw material to the bioreactors were characterized. These diversities at the beginning of sampling and after cultivation were compared. Desulfovibrio, Desulfobulbus, and Desulfomicrobium genus as dominant among sulfate reducers in the bioreactors were detected. The Desulfobulbus species were dominant among other SRB genera before cultivation, but these bacteria were detected only in three out of the seven bioreactors after cultivation dominant.

Acetate kinase Activity and Kinetic Properties of the Enzyme in Desulfovibrio piger Vib-7 and Desulfomicrobium sp. Rod-9 Intestinal Bacterial Strains.

Activity of acetate kinase in cell-free extracts and individual fractions and the kinetic properties of the enzyme obtained from the Desulfovibrio piger Vib-7 and Desulfomicrobium sp. Rod-9 intestinal bacterial strains were presented at the first time. The highest activity of the enzyme was measured in the cell-free extracts (1.52 ± 0.163 and 0.46 ± 0.044 U × mg-1 protein for D. piger Vib-7 and Desulfomicrobium sp. Rod-9, respectively) compared to other fractions. The specific activity of acetate kinase in the extracts of both bacterial strains was determined at different temperature and pH. Analysis of the kinetic properties of the purified acetate kinase was carried out. The acetate kinase activity, initial (instantaneous) reaction rate (V0) and maximum rate of the acetate kinase reaction (Vmax) in D. piger Vib-7 and Desulfomicrobium sp. Rod-9 intestinal bacterial strains were defined. Michaelis constants (KmAcetyl phosphate and KmADP) of the enzyme reaction (2.54 ± 0.26 and 2.39 ± 0.24 mM for D. piger Vib-7 as well as 2.68 ± 0.25 and 2.47 ± 0.27 mM for Desulfomicrobium sp. Rod-9, respectively) were calculated. The described results of acetate kinase, an important enzyme in the process of organic compounds oxidation and dissimilatory sulfate reduction would be perspective and useful for clarification of the etiological role of these bacteria in the development of inflammatory bowel diseases in humans and animals.

Metabolic activity of sulfate-reducing bacteria from rodents with colitis

Abstract Sulfate-reducing bacteria (SRB) are anaerobic microorganisms, which use sulfate as an electron acceptor in the process of dissimilatory sulfate reduction. The final metabolic product of these anaerobic microorganisms is hydrogen sulfide, which is known as toxic and can lead to damage to epithelial cells of the large intestine at high concentrations. Different genera of SRB are detected in the large intestine of healthy human and animals, and with diseases like Crohn’s disease and ulcerative colitis. SRB isolated from rodents with ulcerative colitis have produced 1.14 (mice) and 1.03 (rats) times more sulfide ions than healthy rodents. The species of Desulfovibrio genus are the most widespread among all SRB in the intestine. The object of our research was to observe and compare the difference of production of sulfide and reduction of sulfate in intestinal SRB isolated from healthy rodents and rodents with ulcerative colitis.

A new combination of substrates: biogas production and diversity of the methanogenic microorganisms

Abstract Agriculture, food industry, and manufacturing are just some of the areas where anaerobic technology can be used. Currently, anaerobic technologies are mainly used for wastewater treatment, solid waste treatment, or for the production of electrical and thermal energy from energy crops processing. However, a clear trend is towards more intensive use of this technology in biomass and biodegradable waste processing and hydrogen or biomethane production. An enormous number of anaerobic digesters are operating worldwide but there is very little information about the effect of different substrate combinations on the methanogens community. This is due to the fact that each of the anaerobic digesters has its own unique microbial community. For the most effective management of anaerobic processes it would be important to know the composition of a consortium of anaerobic microorganisms present in anaerobic digesters processing different input combinations of raw material. This paper characterizes the effect of the input raw materials on the diversity of the methanogen community. Two predominant microorganisms in anaerobic digesters were found to be 99% identity by the sequences of the 16S rRNA gene to the Methanoculleus and Thermogymnomonas genera deposited in GenBank.

Model-based Characterization of the Parameters of Dissimilatory Sulfate Reduction Under the Effect of Different Initial Density of Desulfovibrio piger Vib-7 Bacterial Cells.

The objective of this study was to design a model of dissimilatory sulfate reduction process using the Verhulst function, with a particular focus on the kinetics of bacterial growth, sulfate and lactate consumption, and accumulation of hydrogen sulfide and acetate. The effect of the initial density (0.12±0.011, 0.25±0.024, 0.5±0.048 and 1.0±0.096 mg cells/ml of medium) of the sulfate-reducing bacteria Desulfovibrio piger Vib-7 on the growth and dissimilatory sulfate reduction was studied. The exponential growth phase of the D. piger Vib-7 was observed for 72 hours of cultivation at the (0.12 and 0.25 mg/ml) initial concentration of bacterial cells. Sulfate and lactate were consumed incompletely during this time. The increase in the initial concentration of cells to 0.5 and 1 mg/ml led to a shortening of the exponential bacterial growth phase and a shift to the stationary phase of the growth. In the case of 0.5 mg/ml seeding, the stationary growth phase was observed in the 36th hour of cultivation. The increase in the initial concentration of cells to 1 mg/ml led to the beginning of the stationary growth phase in 24th hours of cultivation. Under these conditions, sulfate and lactate were consumed completely in the 48th hour of cultivation. The kinetic analysis of the curves of bacterial growth and the process of dissimilatory sulfate reduction by D. piger Vib-7 was carried out.

Cross-correlation analysis of the Desulfovibrio growth parameters of intestinal species isolated from people with colitis

Sulfate-reducing bacteria can be involved in inflammatory bowel disease. Cross-correlation parameters of their metabolic process in the gut have never been reported before. The aim of the research was to statistically (cross-correlation) evaluate the parameters of growth (biomass) of Desulfovibrio species from colitis people and healthy as well as to investigate the change in dissimilatory sulfate reduction of these bacterial strains. The microbiological, biochemical, chemical, and statistical methods were used in the research. The cross-correlation analysis indicates that the strains isolated from people with colitis shifted to the right side of Y axe by biomass accumulation, sulfate consumption, lactate oxidation as well as hydrogen sulfide and acetate production, compared with the strains isolated from healthy individuals. Different percentages were observed in shifting to the right side of Y axe: biomass accumulation 26%, sulfate consumption 1.5%, sulfide production 5%, lactate oxidation 3% and acetate production 12%. The biomass accumulation of intestinal sulfate-reducing bacteria and their hydrogen sulfide production are the main factors in inflammatory bowel disease development, including ulcerative colitis. Acetate production showed lesser influence while sulfate consumption and lactate oxidation are negligible factors in the inflammatory bowel disease.