RU2567150C1 - Streptococcus thermophilus STRAIN USED FOR PRODUCTION OF FERMENTED MILK PRODUCTS - Google Patents

Abstract

FIELD: biotechnologies.

SUBSTANCE: strain Streptococcus salivarius Bo4-I with high antagonistic activity is deposited in the All-Russian Collection of Industrial Microorganisms under the registration number VKPM V-10893 and can be used for production of fermented milk products and pro-biotic preparations.

EFFECT: invention allows to obtain more viscous milk coagulum.

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Description

The invention relates to biotechnology and the dairy industry and is a new strain of thermophilic streptococcus, intended for the production of dairy products and bacterial preparations.

Known strain of Streptococcus thermophilus VKPM B - 4463/27 (AC No. 1664838), which has increased resistance to growth inhibitors, the ability to stably form a viscous, milk clot, indestructible with stirring, good compatibility with other strains of lactobacilli and pronounced physiological and biochemical properties.

The disadvantage of this strain is low antibiotic activity against opportunistic and pathogenic microflora.

The closest analogue (prototype) is a bacterial strain Streptococcus thermophilus VKPM B-9587 (P. RU 2337953). A bacterial strain was obtained without the use of mutagens and genetic manipulations that is resistant to a number of adverse factors that occur during the process of fermentation of milk.

The disadvantage of this strain is low antibiotic activity against opportunistic and pathogenic microflora.

The objective of the invention is the creation of a fermented milk product using lactobacilli, on accessible nutrient media with high antagonistic activity.

The problem is solved by using nutrient media of dense and liquid consistency: sterile skim milk, hydrolyzed milk (pH 6.8–7.0), unsalted cheese whey with a content of at least 4.0% sugar.

A local strain of Streptococcus thermophilus was isolated under natural conditions of North Ossetia-Alania from the surface of an oriental wrestler plant.

The identification of the strain was carried out according to the method described in the book of L.A. Bannikova (1975).

The strain is deposited in the All-Russian collection of industrial microorganisms and has a number VKPM B-10893.

The strain of Streptococcus thermophilus VKPM B-10893 has the following characteristics.

1. Cultural and morphological:

- optional anaerobic;

- gram-positive cocci;

- diameter 0.6 ± 0.03 μm;

- motionless;

- located - chains of coccoid cells;

- do not form endospores.

On the surface of the agar medium (MRS agar) after 24 hours at a temperature of 37 ° C form:

- rounded colonies;

- point size;

- the nature of the contour of the edge is smooth;

- profile - convex;

- White colour;

- structure - fine-grained;

- the consistency is soft.

The study of the cultural or morphological properties of the selected strain of lactic acid microorganisms was carried out on a dense nutrient medium - agarized milk and MRS agar.

2. Physiological and biochemical:

- milk fermentation rate - 8 hours;

- the limit of acid formation is 211 ° T;

- the strain ferments glucose, sucrose, fructose, raffinose, lactose;

- grows in milk at a temperature of 37-45 ° C;

- grows in milk containing methylene blue (0.01%);

- withstands heating for 30 minutes at a temperature of 55 ° C, 60 ° C.

The product synthesized by the strain is lactic acid, antibiotic substances.

3. Antibiotic activity:

- the diameter of the zone of inhibition of growth in relation to the representative of the pathogenic microflora Staphylococcus aureus was 17 mm;

- the diameter of the zone of growth inhibition in relation to the representative of opportunistic microflora of Escherichia coli was 18 mm.

The antibiotic activity of the strain of Streptococcus thermophilus VKPM B-10893 was determined on a solid nutrient medium (MPA) by agar diffusion.

The method, conditions and composition of the media for long-term storage of the strain - lyophilization; at a temperature of 4-6 ° C; environments: MPS; Rogosa et al .; milk with chalk; milk with yeast autolysate, glucose, litmus, liver extract and CaCO ₃ ; agarized milk cheese whey.

The method, conditions and composition of the media for the propagation of the strain at a temperature of 37 ° C; medium: MPS agar; skim milk, unsalted cheese whey with a content of at least 4.0% sugar.

Optimum conditions and composition of the medium for fermentation - temperature 37 ° C; Medium: MPS agar, unsalted whey whey with a content of at least 4.0% sugar, skimmed cow's milk.

The proposed new strain of Streptococcus thermophilus VKPM B-10893, isolated from the surface of an oriental wrestler plant, is well adapted to local conditions, easy to cultivate and store, can be used in the production of dairy products, is not zoo and phytopathogenic, and is not dangerous for other reasons .

Due to its pronounced biological and antibiotic properties (the ability to form a viscous milk clot, the diameter of the zone of inhibition of growth of Staphylococcus aureus is 17 mm, Escherichia coli is 18 mm), the strain is of industrial value for the dairy industry.

Example. Preparation of yogurt in Mechnikovskoy tank method using bacterial starter culture, which includes the proposed strain of Streptococcus thermophilus VKPM B-10893.

To prepare a laboratory starter culture in 100 ml of sterilized skim milk at 37 ° C make one portion of the starter culture, consisting of S.thermophilus VKPM B-10893 and L.bulgaricus. Fermented milk is kept at the indicated temperature for 6-8 hours until a clot forms.

Production ferment is prepared by adding 100 ml of laboratory ferment in 10 liters of sterilized skim milk. Fermented milk is kept at 37 ° C for 6-8 hours until a clot forms.

Manufacturing sourdough is characterized by a clean, sour-milk taste, a uniform viscous consistency, titratable sourdough acidity of 85 ° T, micropreparations of cocci chain and single sticks.

For the preparation of yogurt, Mechnikovskaya, 3-5% of the production yeast is added to the prepared milk. The ripening process takes place at 37 ° C for 6-8 hours until a dense clot forms. The resulting product is mixed and served on bottling.

Claims (1)

Strain Streptococcus thermophilus VKPM B-10893 used in the production of dairy products.