[Features of dynamics of growth and formation of uncultivable forms in Lactococcus lactis].

Aim: Study strain differences in dynamics of viability and formation of uncultivable forms of Lactococcus lactis.

Materials And Methods: 3 strains of L. lactis--MSU, 729 and F116 were used in the study.

[Characteristics and identification of bacteriocins produced by Lactococcus lactis subsp. lactis 194-K].

The Lactococcus lactis subsp. lactis 194-K strain has been established to be able to produce two bacteriocins, one of which was identified as the known lantibiotic nisin A, and the other 194-D bacteriocin represents a polypeptide with a 2589-Da molecular mass and comprises 20 amino acid residues. Both bacteriocins were produced in varying proportions in all of the studied nutrient media, which support the growth of the producer.

[Antibacterial metabolites of lactic acid bacteria: their diversity and properties].

The review is devoted to literature data on antimicrobial metabolites produced by lactic acid bacteria (LAB), which have long been used for the preparation of cultured dairy products. This paper summarizes data on low-molecular-weight antimicrobial substances, which are primary products or by-products of lactic fermentation. Individual sections are devoted to a variety of antifungal agents and bacteriocins produced by LAB; their potential use as food preservatives has been discussed.

[Microbiological characterization of a new strain of Lactococcus lactis subsp. lactis K-205].

Bacteriocin-producing strain Lactococcus lactis K-205 with antibacterial activity up to 2,700 IU/ml (calculated on nisine-producing activity) was isolated from Buryat beverage kurunga. Using genotypic analysis of oligonucleotide sequence of 16S rRNA gene, the strain was identified as L. lactis subsp.

[Variability of nisin-synthesizing wild strain Lactococcus lactis subsp. lactis 119 under the effect of ultraviolet light].

To increase the nisin synthesizing activity of the natural strain Lactococcus lactis subsp. lactis 119 isolated from sour milk, UV irradiation in different doses was used followed by isolation of productive clones. The highest mutation effect was observed with the dose of 76,000 erg/mm2, when 11% of the cells increased their productivity by 12.

[A comparison of the properties of bacteriocins formed by Lactococcus lactis subsp. lactis strains of diverse origin].

Bacteriocins formed by four strains of Lactococcus lactis subsp. lactis have been studied and compared: 729 (a natural strain isolated from milk), 1605 (a mutant of strain 729), F-116 (a recombinant obtained by fusing of protoplasts of the two related strain 729 and 1605), and a nisin-forming strain obtained by adaptive selection at Moscow State University. Antimicrobial activity studies revealed differences between the strains in the effects on individual groups of microorganisms; the activities of the strains were also distinct from that of Nisaplin (a commercial preparation of the bacteriocin nisin).

[Isolation and identification of new nisin-producing Lactococcus lactis subsp. lactis from milk].

A method for isolating active nisin-producing strains of mesophilic lactococci was developed. Overall, 55 strains of mesophilic lactic acid bacteria were isolated from fresh cow's milk obtained from milk farms in various regions throughout Russia; of them, 36 displayed nisin-synthesizing activity. The three most active strains were studied according to morphological, cultural, physiological, and biochemical characteristics and identified as Lactococcus lactis subsp.

[Components of fermentation medium regulate bacteriocin synthesis by the recombinant strain Lactococcus lactis subsp. lactis F-116].

The regulation of the synthesis of bacteriocin produced by the recombinant strain Lactococcus lactis subsp. lactis F-116 has been studied. The synthesis is regulated by the components of the fermentation medium, the content of inorganic phosphate (KH2PO4), yeast autolysate (source of amine nitrogen), and changes in carbohydrates and amino acids.

[Comparison of methods of storing lactic acid bacteria].

The study was undertaken to elucidate how different methods of storage (immersing in mineral oil, lyophilization, and subculturing) of lactic acid bacteria belonging to the genera Lactobacillus and Lactococcus affect their viability, antibiotic activity, and ability to accumulate organic acids. Storage of the lactic acid bacterium L. lactis subsp.

[The development of a nutrient medium for nisin-producing streptococci utilizing the waste products from a number of biotechnology plants].

The possibility of using some waste products of the dairy and agricultural industries as nutrient substrates for the cultivation of nisin-producing streptococci was studied. Yeast production wastes as well as potato liquor, whey and dried whey as waste products were shown suitable for the growth of Streptococcus lactis and the biosynthesis of nisin. The level of the nisin production increased when corn steep liquor and glucose were added to whey and dried whey respectively.

[Various aspects of protoplast production in Streptococcus lactis].

The authors studied the effect of some factors, including the conditions of preincubation, the action of 2-mercaptoethanol, EDTA, alpha-amylase, on protoplast production in four strains of Streptococcus lactis caused by lysozyme. The strains differed in the nisin-producing activity and in the structure of the cell walls that were not affected with lysozyme without either preincubation in 2-mercaptoethanol or in a salt medium with minimal inhibitory concentrations of DL-threonine. EDTA and alpha-amylase increased the lysozyme effect.

[Sublimation-dried mare's milk and the possibility of its use in creating infant and dietary food products].

The main biological parameters were studied in sublimated mare's milk: protein fraction composition, amino-acid spectrum, fatty-acid composition of lipids and the content of vitamins and mineral substances. A high biological value of the sublimated mare's milk has been proved, as well as significant proximity of its composition to human milk. Preliminary data have evidenced expediency of mare's milk use for the development of adapted milk mixtures for baby foods.

[Use of the method of protoplast fusion in the selection of a nisin producer].

Experimental data on selection of Streptococcus lactis producing the polypeptide antibiotic nisin with the method of protoplast fusing, one of the modern methods of cell engineering are presented. Four strains of Streptococcus lactis differing in their nisin-producing levels and difficult for protoplasting were used in the study. It was shown possible to transfer them to the protoplast form when respective conditions for their preliminary cultivation and regeneration are provided.

[Physiologo-biochemical features of the growth and development of Propionibacterium shermanii in egg albumin].

Propionibacterium shermanii was shown to be able of growing in such an unusual substrate as egg albumen. Incubation of the bacterium in egg albumen results in complete utilization of free carbohydrates in this substrate and accumulation in it of such bacterial metabolites as vitamins B2 and B12, free amino acids, bacterial protein, acetic and propionic acids which favour conservation of egg albumen. The bacterium does not possess proteolytic activity and does not utilize albumen; in the conditions of nitrogen deficiency, it can utilize free amino acids in the substrate.

[Antimicrobial and antispirochetal activity of Pharmachem's tylosin].

Studies are the following preparations, produced by "PHARMACHIM": tylosine-base (Tylosine-50), tylosine tartarate (Tylosine pulvis) and tylosine phosphate (substance and granules) and their analogues: tylosine-base (Tylan-50), tylosine tartarate (Tylan soluble) and tylosine phosphate (Tylan AF 99), produced by the "Elanco" Company. The biological activity of the preparation was determined by means of the microbiological method of diffusion in agar. In the case of all experimental treatments, the preparations were compared in conformity with their biological activity expressed in IU/mg of the preparations.

[Production of trivalent vaccine against avian spirochetosis].

Reshetnyak's method was employed to produce a trivalent vaccine against avian spirochetosis, using the serotypes Surnevo I, Pamoukchii, and Venets established in this country. The vaccine was tested for sterility, innocuity, and immunogenicity. Its activity was determined via biologic titration on birds.

[Desugarization of egg white by microorganisms].

Glucose was eliminated from egg whites, using microorganisms, to prevent melanoidin formation which may damage the product. Desugarization was achieved by means of Acetobacter xylinum, Streptococcus lactis, Propionibacterium shermanii, Pr. petersonii and propionicacid cocci.

[Effectiveness of sodium arsamilate and its effect on the immunity of hens experimentally infected with Borrelia anserina].

The toxicity of sodium arsanilate for chickens was determined following a six-day oral application. Doses higher than 0.15/kg body weight led to symptoms of intoxication and death, especially when the intake of water was restricted.

[Test of the effectiveness of tylan on spirochetosis in chickens].

The water-soluble preparation Tylan in conc. 1:2000 in the drinking water for three consecutive days was used successfully against spirochetosis in birds both experimently and in the field practice, as a therapeutic and prophylactic means. 175 (92 per cent) out of 190 affected birds in a spontaneous breakout of spirochetosis recovered.