Vladimir Chistyakov

Functions and emerging applications of bacteriocins

Bacteriocins, defined as ribosomally synthesized antimicrobial peptides, have traditionally been used as food preservatives, either added or produced by starter cultures during fermentation. In-depth studies of a select few bacteriocins opened exiting new research fields and broadened the application of these antimicrobial peptides. The possibility of developing bacteriocins into next generation antibiotics, accompanied with the rapid development in genetics and nanotechnology, paves the way to even more fascinating applications such as novel carrier molecules (delivery systems) and the treatment of cancer. Also, some bacteriocins are found to regulate quorum sensing which suggests novel applications for this group of substances. While there is some interesting translational research on bacteriocins from Gram-negative bacteria, the majority of application-oriented studies are focused on bacteriocins from Gram-positive microorganisms, mostly lactic acid bacteria. The applications of bacteriocins are expanding from food to human health.

Poultry-beneficial solid-state Bacillus amyloliquefaciens B-1895 fermented soybean formulation

Birds were given a new formulation of the Bacillus amyloliquefaciens B-1895 solid-state fermented soybean that retained the spores of the aforementioned organism. Mass dynamics, feed flow rate and broiler performance were observed to evaluate the efficacy of the formulation. At each time point, the live mass was greater than that of the control group, reaching a difference of 7–8% by day 28. A difference of 5.3–8.8% was observed in feed conversion per kilogram live mass (1.97 kg in the controls as compared with 1.81–1.87 kg in experimental groups). This indicates a positive effect of the B. amyloliquefaciens B-1895 formulation on the live mass of broilers as well as on feed consumption.

Synthesis and biological properties of nitrobenzoxadiazole derivatives as potential nitrogen(ii) oxide donors: SOX induction, toxicity, genotoxicity, and DNA protective activity in experiments using Escherichia coli-based lux biosensors

Dihetaryls containing superelectrophilic and π-excessive heterocycles were synthesized by the nucleophilic aromatic substitution and cycloaddition. The structures of the compounds and the mechanism of 1,3-N-oxide tautomerism were studied by NMR spectroscopy, X-ray diffraction, and quantum chemical methods. The ability of these compounds to initiate SOX induction, which is probably due to the in vivo generation of nitrogen(ii) oxide, was quantified using genetically engineered E. coli-based lux biosensors. 7-(1-Methylpyrrol-3-yl)-4,6-dinitrobenzofuroxan is the most active inducer, which is an order of magnitude more effective than nitroglycerin used as the reference compound. The absence of toxicity was established using the E. coli MG 1655 biosensor (pXen7-lux). The DNA protective effect of this leading compound was confirmed using the E. coli MG 1655 biosensor (pRecA-lux).

Synthesis, Genotoxicity and UV-protective Activity of New Benzofuroxans Substituted by Aromatic Amines

The synthesis of new organic compounds possessing properties, which can be used for biological or pharmaceutical purpose, is very challenging and is a current trend in heterocyclic chemistry. So benzofuroxans are of great interest from a medical and combinatory chemistry point of view, being effective biologically active compounds. They are easily available, easily tuned and functionalized allowing the creation of databases in which a chemist can find proper informations to prepare the structurally appropriate compound with the requested selective effect. In this work, heterocyclic compounds are prepared on the basis of the interaction of 4,6-dichloro-5-nitrobenzofuroxan with aromatic amines and diamines. Their ability to suppress and prevent genotoxic effects of UV-radiation in the wavelength range between 300-400 nm has been studied. It has been shown that these compounds are able to protect bacterial cells from destructive effects of the UV-radiation. Comparing the results obtained for various benzofuroxans to those obtained for the natural antioxidant  - tocopherol (vitamin E) and for the synthetic antioxidant trolox, which are references in this domain, we have shown that some benzofuroxans quantitatively exhibit a similar protective effect, and that compounds prepared from the reaction between 4,6-dichloro-5-nitrobenzofuroxan and ethylenedianiline possess potent protective potential.

Fullerenes as Anti-Aging Antioxidants

Here we review fullerenes biological effects focusing on their antioxidant and anti-ageing action. A scope of various poisonous and healing properties reported in literature for fullerene and its derivatives is analyzed. The review begins with the history of fullerenes discovery and their main properties. Then we focus on the longevity and antioxidant action, including the confrontation of available experimental data and theoretical modeling of buckminsterfullerene C60. Special attention is given to our hypothesis concerning the possibility of fullerenes to act as mitochondria protonophore and various simulations of the transport of C60 and its hydroxylated and other derivatives through lipid bilayer membranes, which can account for scavenging capacity of fullerenes for reactive oxygen species and their acting as mild mitochondrial respiration uncouplers. Extension of the theoretical modeling to the mitochondria membranes and implications on the real biological systems is analyzed. Finally, we focus on the toxicity evaluation and current therapeutic usage of fullerenes. The review contains a comprehensive discussion of both papers published by 2016 and our own research results.

Genotoxicity of Don River bottom sediments (2001–2007)

Data on genotoxicity of Don River bottom sediments in 2001–2007 are given. The regions of Lower Don are identified where genotoxin pollution has a chronic character are identified. The possible sources of their input are discussed.

Chemiluminescence analysis of oil oxidizing bacteria Actinetobacter calcoaceticus extracts: Effects of the extracts on pSoxS-lux biosensor

A comparative H2O2-luminol- and Fe(II)-induced chemiluminescence analysis of extracts of two strains of marine oil oxidizing bacteria Actinetobacter calcoaceticus cultivated either in the presence or absence of oil was carried out. Effects of these extracts on E. coli MG1655 biosensor (pSoxS-lux) were studed. Activation of H2O2-induced chemiluminescence in the presence of oil was observed. This suggests activation of free radical lipid peroxidation. Aqueous extracts of microorganisms cultivated in the presence of oil were shown to activate reactive oxygen species production (ROS) in Fe(II)-induced chemiluminescence reaction mixture. Acetone-ethanol extracts induced antioxidative systems of both strains. Chemiluminescence analysis in a biological system carried utilizing E. coli MG1655 (pSoxS-lux) revealed that aqueous extracts of the strains cultivated in the absence of oil contained potential antioxidants.

Nitrobenzoxadiazole derivatives as nitric oxide donors: ESR study using spin trapping

The ability of nitrobenzoxadiazoles to induce the SOX-operon from a genetically engineered biosensor based on E. coli MG 1655 (pSoxS-lux) was confirmed by the fact of producing nitric oxide. The NO-donating properties of three nitrobenzoxadiazole derivatives bearing π-excessive carbo- and heterocycles were found by the ESR method using spin trapping. The yield of nitrogen(II) oxide was 17, 0.3, and 1.6%. Sodium sulfide accelerates the thiol-dependent transformation and increases the yield of nitric oxide to 27, 16, and 12%, respectively.

Methods to Assess the Antioxidative Properties of Probiotics

Probiotics prove useful in correcting and preventing numerous health conditions, including those having severe impact on society, e.g., obesity and cancer. Notably, these capabilities of probiotics appear to be associated with their antioxidant properties. The mechanisms of antioxidant action of probiotics range from immediate biochemical scavenging of reactive substances to induction of signaling events leading to increased capacity of the host’s cytoprotective systems. Since the antioxidant effects of probiotics significantly vary in types and details, a broad selection of methods of assessment of these properties is required in order to identify, characterize, and develop novel probiotics for medical purposes, as well as to explain the mechanisms of action of probiotics already in use in healthcare. This review revises the versatile toolbox, which can be used to assess the antioxidant properties of probiotics.

The Use of Biosensors to Explore the Potential of Probiotic Strains to Reduce the SOS Response and Mutagenesis in Bacteria

A model system based on the Escherichia coli MG1655 (pRecA-lux) Lux-biosensor was used to evaluate the ability of the fermentates of eight probiotic strains to reduce the SOS response stimulated by ciprofloxacin in bacteria and mutagenesis mediated by it. Preliminary attempts to estimate the chemical nature of active components of the fermentates were conducted.