CS260445B1 - Method of differentiation of Streptococcus lactis, Streptococcus cremoris and other bacterial species metabolizing sugars - Google Patents

Abstract

The proposed differentiation method allows to distinguish related strains that have the ability to form acids on growth agar, and that differ in the ability to utilize some amino acid from the agar growth medium while releasing ammonium ions into the environment. Colonies differ on growth agar that contains a suitable pH indicator dye (bromcresol purple) and bentonite. Colonies of Streptococcus cremoris with the ability to form acids are yellow to orange and have a yellow zone around them. Colonies of Streptococcus lactis, which also have the ability to utilize some amino acid and release ammonium ions into the environment, become white to blue again with a blue zone after 2 to 3 days.

Description

The present invention relates to a method for distinguishing bacterial species of Streptococcus lactis in addition to Streptococcus cremoris and all related bacterial species capable of metabolizing sugars to form acids that differ in their ability to utilize an amino acid on bentonite-containing agar media.

The current method of distinguishing Streptococcus lactis and Streptococcus cremoris was possible only to a very limited extent, since this distinction could only be made by workers with a high degree of microscopic image in which the species differ slightly. A distinction can also be made according to the size of the colonies on agar plates, which are however very inaccurate, as there is a large variation in the size of the colonies between the individual strains of individual species and there is a considerable overlap of statistical colonial size curves between the individual species. Although a method for distinguishing Streptococcus lactis and Streptococcus cremoris has been described worldwide, it has not been spread due to the very laborious preparation of the medium containing carboxymethylcellulose.

The essence of the solution lies in the general property of all lactic acid streptococci to form lactic acid, which is excreted into the environment with the pH indicator dye bromo-chalkpurpur, which changes from blue to yellow, and secondly in its ability to utilize arginine as a carbon source. releasing ammonium ions into the environment, which basify the environment, thus turning the yellow color around the colonies again to mcdrou. Bentonite, due to its ion-exchange properties, prevents the released metabolites from spreading to a wide area. In addition, bentonite is a microelement standard and self-toxic products allow colonies to grow in a more compact form, which results in better background resolution and overall smaller colony diameter. This property is advantageous especially in denser growths on agar plates, where there is no significant interactions between colonies.

Example

The basic medium contains:

Claims (3)

SUBJECT A method for distinguishing Streptococcus lactis alongside Streptococcus cremoris and other bacterial carbohydrate metabolizing species to form acids, characterized in that strep4S 5 g cryptone; 5 g yeast extract; 2.5 g of casein enzymatic hydrolyzate; 5 g arginine HCl; 1.25 g KrHPO3; 10 g of calcium citrate; 15 g bentonite and 15 g agar. After dissolution, the pH is adjusted to values 5.6. 6-N HCl and sterilize at 121C for 15 min. Just before pouring into Petri dishes, add 5 ml of 10% sterile reconstituted skim milk, 10 ml of sterile CaCOs in distilled water, and 2 ml of sterile 0.1% aqueous bromocresourpurpur solution for each 100 ml of agar medium dissolved and allowed to reach 55 ° C. . Carefully mixed medium is poured onto 3 to 4 mm agar petri dishes. Inoculation: Spread 0.1 ml of the appropriate dilution on the surface of the agar plate. Incubation: The inoculated culture dishes are incubated at 30 ^° C for 2-3 days. Colonies reading: After 64 hours incubation: Streptococcus cremoris N4 strain: on sand-colored soil, there are yellow to orange colonies with a distinct yellow zone around. The average colony size is 1.22 mm with a standard deviation of 0.2 mm. Strain Streptococcus lactis 358: on yellow-violet soil there are large white colonies with a blue zone around. The average colony size is 3.23 mm with a standard deviation of 0.91 mm. The advantages of the invention lie in particular in the refinement of the diagnostic methodology for lactic acid bacteria. Due to its relative simplicity and availability of domestic raw materials, it will have a significant application in industrial microbiology, dairy and other food industry sectors.