The objective is to perform a comparative evaluation of the pancreatic hydrolysates prepared from fish and squid to determine the optimal culture medium for Listeria monocytogenes.Materials and methods. The following raw materials were used in the study: Pacific Herring (Clupea pallasii), Alaska Pollock (Gadus chalcogrammus), Common Roach (Rutilus rutilus lacustris), European Squid (Loligo vulgaris). The raw materials were subjected to enzymatic hydrolysis using the pancreas (according to Hottinger). A study of the physicochemical properties of pancreatic hydrolysates (content of free amino nitrogen (FAN), acidity of fish hydrolysates, the amino acid composition) was carried out.. The specific activity of nutrient media during the cultivation of the test strain L. monocytogenes 766 was assessed by a complex of microbiological methods.Results and discussion. The highest content of FAN at the end of enzymatic hydrolysis was observed in the pancreatic hydrolysate of the common roach (6%), the acidity of the hydrolysate remained stable from 6th to 13th day of the hydrolysis process (pH 7.2). Pancreatic hydrolysate of the common roach contained a number of amino acids that are most essential for the growth of Listeria. An assessment of the biological properties of nutrient media prepared on the basis of the obtained hydrolysates demonstrated that the best results in terms of sensitivity and germination of L. monocytogenes 766 showed a nutrient medium based on the pancreatic hydrolysate of the common roach. During the cultivation of L. monocytogenes 766 the test strain retained its morphological and cultural properties and did not show signs of dissociation.Conclusion. The research results have shown that the pancreatic hydrolysate of the common roach is a promising protein basis for the construction of an experimental environment for listeria.

The causative agent of listeriosis refers to pathogens when clinical diagnosis is difficult due to the polymorphism of the manifestation of the disease. In this regard, the use of express methods of laboratory diagnostics, which include the agglutination reaction, is an urgent need for rapid diagnosis and timely treatment. To obtain an experimental diagnostic listeriosis agglutinating highly specific serum, a sufficient volume of immunogen is required, the source of which is the inactivated bacterial mass of Listeria monocytogenes 766. The development of a bacterial nutrient medium for the cultivation of listeriosis microbe is caused by need to ensure high growth of listeria biomass in a short time. Pacific herring (Clupea pallasii), pollock (Gadus chalcogrammus), roach (Rutilus rutilus) and European squid (Loligo vulgaris) were used as raw materials for obtaining hydrolysates. Comparative physico-chemical studies of tested nutrient bases have shown that optimal basis of nutrient medium is pancreatic hydrolysate of roach, in which the maximum indicators of enzymatic process speed, the content of amine nitrogen, stable preservation of acidic properties for a long time are determined. Using the method of NMR spectroscopy, the amino acid composition of the nutrient medium for accumulation of listeria biomass was established, which is represented by alanine, valine, threonine, arginine, lysine, leucine, methionine, histidine, tyrosine and tryptophan and the amino acids phenylalanine and glycine, which are most important for the growth of listeria. It was found that nutrient medium based on pancreatic hydrolysate of roach had advantages over other bases (Pacific herring, pollock and European squid pancreatic hydrolysates) in terms of germination, sensitivity and efficiency, growth rate of the nutrient medium for listeria cultivation, while maintaining the typical listeria cultural-morphological, biochemical and serological properties. It has been established that effectiveness of experimental nutrient medium f, designed by specialists of laboratory of nutrient media of Irkutsk Anti-Plague Institute, is not inferior to such commercial medical products as GRM-agar and meatpeptone agar. Experimental results confirmed the ability of culture medium for the cultivation of listeria to preserve the biological properties of test strain L. monocytogenes 766 (collection of pathogenic bacteria of the Irkutsk Anti-Plague Institute) for one year. Based on the data obtained, we concluded that the high growth rates of listeria on proposed nutrient medium were achieved through use of pancreatic roach hydrolysate and components optimal concentrations that stimulate the growth of listeria, providing a significant accumulation of bacterial mass in shortest possible time.

Background. Development of nutrient media ensuring the maximum growth rate of pathogens of dangerous infectious diseases while preserving their biological properties is extremely important. A promising direction in this area seems to be the use of synthetic microbial growth biostimulants.The aim of the work is to study the possibility of improving nutrient media for the cultivation of Listeria and Staphylococcus using a biologically active compound tris(2-hydroxyethyl)ammonium 4-chlorophenylsulfanylacetate.Materials and methods. The object of the study was experimental nutrient medium for the cultivation of Listeria used for the culturing of the test strain Listeria monocytogenes 766. As a comparison medium, commercial medium Fraser broth to which agar was added at a concentration of 1.5 %, was used. The test strain Staphylococcus aureus ATCC 6538-P (FDA 209-P) was cultivated on meat-peptone agar with 1% glucose. The compound tris(2-hydroxyethyl) ammonium (4-chlorophenyl)sulfanylacetate at a concentration of 10–4 wt. % was studied as a growth stimulator. A nutrient medium without a stimulant served as a control. The specific activity of nutrient media (germination rate, medium sensitivity, growth rate and stability of the main biological properties of microorganisms) was evaluated by the microbiological method.Results. Studies have shown that the addition of a growth stimulator to nutrient media contributes to the growth of colonies (by 10–50 %) and a decrease in the time of their development. When growth stimulator was added to the nutrient medium for the cultivation of Listeria, the initial growth of colonies of the L. monocytogenes 766 test strain after 12 hours of cultivation and growth of colonies of the test strain S. aureus ATCC 6538-P after 6 hours of cultivation on the meat-peptone agar with 1% glucose was observed.Conclusion. Thus, the addition of a growth biostimulator tris(2-hydroxyethyl)ammonium 4-chlorophenylsulfanyl acetate at a concentration of 10–4 wt. % in the nutrient medium accelerates the growth of Listeria and Staphylococcus, allows to reduce the time of issuance of the analysis result in half.

Background. Development of nutrient media ensuring the maximum growth rate of pathogens of dangerous infectious diseases while preserving their biological properties is extremely important. A promising direction in this area seems to be the use of synthetic microbial growth biostimulants. The aim of the work is to study the possibility of improving nutrient media for the cultivation of Listeria and Staphylococcus using a biologically active compound tris(2-hydroxyethyl)ammonium 4-chlorophenylsulfanylacetate. Materials and methods . The object of the study was experimental nutrient medium for the cultivation of Listeria used for the culturing of the test strain Listeria monocytogenes 766. As a comparison medium, commercial medium Fraser broth to which agar was added at a concentration of 1.5 %, was used. The test strain Staphylococcus aureus ATCC 6538-P (FDA 209-P) was cultivated on meat-peptone agar with 1% glucose. The compound tris(2-hydroxyethyl) ammonium (4-chlorophenyl)sulfanylacetate at a concentration of 10–4 wt. % was studied as a growth stimulator. A nutrient medium without a stimulant served as a control. The specific activity of nutrient media (germination rate, medium sensitivity, growth rate and stability of the main biological properties of microorganisms) was evaluated by the microbiological method. Results . Studies have shown that the addition of a growth stimulator to nutrient media contributes to the growth of colonies (by 10–50 %) and a decrease in the time of their development. When growth stimulator was added to the nutrient medium for the cultivation of Listeria, the initial growth of colonies of the L. monocytogenes 766 test strain after 12 hours of cultivation and growth of colonies of the test strain S. aureus ATCC 6538-P after 6 hours of cultivation on the meat-peptone agar with 1% glucose was observed. Conclusion . Thus, the addition of a growth biostimulator tris(2-hydroxyethyl)ammonium 4-chlorophenylsulfanyl acetate at a concentration of 10–4 wt. % in the nutrient medium accelerates the growth of Listeria and Staphylococcus, allows to reduce the time of issuance of the analysis result in half.

Background. To obtain reliable results of laboratory studies on the identification of Listeria, the presence of certified diagnostic agglutinating Listeria sera is required. An important step in the manufacturing process of such medical devices for in vitro diagnostics requires effective nutrient media for the accumulation of listeriosis microbe. Aim of the research. To develop an effective nutrient medium for the accumulation of bacterial mass of Listeria. Materials and methods. The object of the study was an experimental culture medium for Listeria cultivation. As a control, we used nutrient agar for the cultivation of microorganisms (fish meal hydrolysate, FMH-agar) and meat-peptone agar with 1 % glucose (MPA with 1 % glucose). The specific activity of nutrient media during cultivation of the test strain Listeria monocytogenes 766 was evaluated using a complex of microbiological methods. Results. The optimal base of the nutrient medium for Listeria cultivation has been selected: pancreatic hydrolysate of river magpie fish (Rutilus rutilus lacustris) and hydrolysate of meat water production waste. The qualitative and quantitative composition of the nutrient medium has been developed, its physical, chemical and biological properties have been studied. It was found that after 24 hours of incubation at 37 °C, the nutrient medium provided the growth of typical Listeria colonies. The germination rate was 85 %, which is higher compared to the growth of the culture on MPA with 1 % glucose and GRM agar by an average of 21 % (p < 0,05). Conclusion. The experimental culture medium for Listeria cultivation provided growth of colonies of the test strain L. monocytogenes 766 with the preservation of characteristic cultural, morphological and biochemical properties, and, in terms of germination and growth rate, exceeded the control media. The developed nutrient medium provides effective growth of Listeria and can be used as a medium for the accumulation of microbial mass.

The traditional approach to assessing the quality of nutrient bases involves a determination of amino nitrogen and acidity. The disadvantage of this approach consists in a lack of information, i.e. an inability to detect antibiotics, growth inhibitors and other undesirable compounds. In this regard, more modern and informative methods are required to control the technological process of preparing the nutritional basis and therefore the quality of the products obtained. The aim of this work was to study the physicochemical properties of nutrient bases made from sea and river fish and squid using new approaches (NMR spectroscopy). The following raw materials were used: herring (1), roach (2), pollock (3), squid (4). The raw materials were subjected to enzymatic hydrolysis by the pancreas (according to Hottinger). The qualitative composition of the organic component of hydrolysates (1–4) was determined by 1 H, 13 С and 15 N NMR spectroscopy. All of the 1H NMR spectra had the same appearance, typical of mixtures of amino acids or amino acid sequences. In the high-field part (0.9–2.5 ppm), a set of multiplets was observed, characteristic of aliphatic fragments of molecules. Since most of the signals in the 1H NMR spectra partially overlap, a quantitative assessment of the composition of the organic component appears impossible. All four samples can be confirmed as being qualitatively similar without isolating the dominant compound. Analysis of 2D NMR spectra revealed the presence of the following free amino acids in mixtures of samples (1–4): alanine, valine, threonine, arginine, lysine, leucine, methionine, phenylalanine and glycine. The use of NMR spectroscopy demonstrated that any discrepancies in the component composition of hydrolysates (1–4) were insignificant, allowing manufacturers of nutrient media to choose the most affordable raw materials. The obtained data appear to be applicable for controlling the technological process of preparing the nutrient bases and determining the quality of the resulting products during storage.