Vol 60, No 4 (2024)

The widespread use of antibiotics, leading to antibiotic resistance and the appearance of antibiotics in the environment and food, stimulates the development of new methods for monitoring antibacterial drugs in environmental objects. One of the promising areas for the development of methods for determining antibiotics belongs to sensor technologies. The key point in the development of sensory systems is the selection of a sensitive (recognizing) element. One of the most popular methods for recognizing antibiotics is the use of antibodies. The work presents the main immunosensory systems based on recording the “antigen-antibody” interaction and shows the advantages and disadvantages of polyclonal and monoclonal antibodies. The possibility of using phage antibodies to determine of antibiotics is described separately.

The work investigated the effect of four enzyme preparations (EP): Bacillolysin, Agroprot, Protozyme and Protozyme C (Russia), on smell, taste, as well as protein and peptide profiles of protein isolate isolated from Focor peas. It has been shown that enzyme treatment improves the odor characteristics of the isolate. Thus, it was possible to significantly reduce the severity of bean and herbal smell. At the same time, enzyme treatment also improved the taste of the isolate: it was possible to significantly reduce the severity of such disturbing flavors as legume, astringent, bitter and herbal. The results obtained made it possible to select EP (fungal acidic aspartate proteinase) to improve the organoleptic parameters of pea protein isolates intended for the manufacture of analogues of meat and dairy products.

The first line of defense in plants under stress is the cell chaperone system. In this work, we studied the effect of heat stress on the levels of cytoplasmic chaperones HSP70 and HSP70B in chloroplasts of three species of Cucurbita (C. maxima Duchesne, C. pepo L. and C. moschata Duchesne), which differ in resistance to stress. A relationship has been established between the levels of chaperones HSP70 in the cytoplasm and HSP70B in chloroplasts and the species of pumpkin plants under heat stress conditions. Under stress, a significant increase in the level of chaperones was observed in the cells of pumpkin plants C. maxima – the level of HSP70 in the cytoplasm increased by 3.6 times, and the level of HSP70B in chloroplasts – by two times. Heat stress caused a 1.7-fold increase in the level of the cytoplasmic chaperone HSP70 in the cells of C. pepo pumpkin plants, but no significant change in the level of the HSP70B protein was noted. However, as a result of the effect of heat stress on C. moschata pumpkin plants, a decrease in the levels of HSP70 and HSP70B was revealed compared to untreated plants. The dynamics of changes in the levels of chaperones in the cytoplasm and chloroplasts under the influence of heat stress are similar. It should be noted that the constitutive level of HSP70 and HSP70B under normal conditions in C. moschata and C. repo is higher than in C. maxima. Analysis of the data obtained revealed an interesting pattern: high constitutive levels of HSP lead to insignificant induction of HSP and vice versa – low constitutive level of these proteins correlates with high induction of these proteins after heat stress. The data obtained are important for understanding the mechanisms of plant resistance to stress and can be useful for the selection and creation of highly resistant productive varieties of agriculturally important plants.

The effect of the PGPB strain of bacteria Pseudomonas sp. was studied. OBA 2.4.1, resistant to NiCl2 (up to 3 mM), Pb(CH3COO)2 (up to 5 mM) and glyphosate (up to 8 mg/ml), on Pisum sativum L. plants at different concentrations of HMs and herbicide. It was found that the strain under study had a positive effect on the length of the roots of pea plant seedlings in the presence of HM, which indicates an increase in the plant’s resistance to stress caused by exposure to nickel and lead. However, this effect was not recorded in the experimental version with the addition of glyphosate, which confirmed its high toxicity. The results obtained indicate that the strain Pseudomonas sp. OBA 2.4.1 promoted the growth of Pisum sativum L. under stress exposure to nickel and lead, which can be used in the development of complex-action biological products intended both to protect agricultural plants from the effects of heavy metals and to reclaim contaminated soils.

The role of surface antigens of Yersinia pestis in reception of the phage L-413C was experimentally evaluated. Based on the methods of the phage inactivation after its co-incubation with the soluble or bead-bounded antigens, an importance of LPS from the plague microbe in the phage reception and inability to bind a capsular antigen F1, Ail protein and two autotransporters YapF and YapM were confirmed. The native and recombinant PsaA, being solved, significantly inhibited the lytic activity of the phage in comparison with the bead-bound antigens. The knockout EV cells (ΔpsaA) are able to bind the phage particles as well as the wild strain. The use of three methods to evaluate the role of PsaA antigen in phage L-413C reception gave contradictory results. On the one hand the reactive domains of PsaA are able to interact with phage particles in solution. At the same time, these domains appear to determine nonspecific binding of PsaA protein to the underlying bacterial cell structures and polystyrene microsphere, preventing phage adhesion.

The influence of organic solvents such as methanol and acetonitrile on the results of immunodetermination of butachlor in samples of rice and rice products was studied. The schemes of enzyme immunoassay using: (a) native antiserum containing specific antibodies to butachlor and antispecies antibodies labeled with horseradish peroxidase, and (b) biotinylated specific antibodies and streptavidin labeled with peroxidase are considered. The close values of IC₁₀ (0.77 and 0.68 ng/ml, respectively) and working range (2.6–165 and 2.4–192 ng/ml, respectively) were established for the two schemes, when analyzing in a mixture of phosphate buffer and methanol 85 : 15%. For the second scheme, the detection of butachlor in samples of rice and food products based on it is shown at a level of 80–132% of the administered amount of the analyte. The comparison of sample preparation methods allows us to recommend the extraction of butachlor with hexane with redissolution of the dry residue in a buffer with 15% methanol, or the preparation of a methanol extract followed by a 6-fold dilution with a buffer solution.