Study of antimicrobial metabolites of lactic acid bacteria

Аннотация

In the past decades, detailed studies of SAB have revealed their ability to produce antimicrobial substances of various natures.Many SAB strains, in addition to lactic acid, produce a large number of non-specific low molecular weight compounds, such as organic acids, hydrogen peroxide, diacetyl, reuterin, etc., which determine the spectrum of their antimicrobial action.Many SAB strains, in addition to lactic acid, produce a large number of non-specific low molecular weight compounds, such as organic acids, hydrogen peroxide, diacetyl, reuterin, etc., which determine the spectrum of their antimicrobial action.As mentioned above, the main final metabolites produced by SAB during fermentation are lactic and acetic acids.Acetic acid has a broader antimicrobial activity than lactic acid. However, a synergistic effect is known for both acids: A mixture of acetic and lactic acids inhibits the growth of pathogenic gram-negative enterobacteria Salmonella typhimurium.It is noted that L-lactate has a greater inhibitory effect than the D-isomer. Different microorganisms react differently.Depending on the acidity of the environment, for example, at a pH below 5.0, lactic acid inhibits the development of spore-forming bacteria, but does not affect the development of microscopic fungi and yeasts. Keywords: Lactobacillus, strain, probiotic, SAB, isolation, antibacterial activity. antibacterial activity and probiotic properties of Introduction: The search for new promising probiotic Lactobacillus spp., which strains were sensitive to strains, the identification of their probiotic properties, ampicillin. as well as the study of already known probiotic strains are important tasks of basic science.Research aimed at LITERATURE ANALYSIS AND METHODOLOGY isolating and studying new strains of SABs is a Dairy products were used to isolate SAB widespread and urgent issue worldwide.One of the first isolates.Enriched MRS-nutrient medium (Hi-Media, and most important steps in the search and selection India) was prepared, homogenized in sterile saline of a promising strain is to determine its taxonomy, (0.85%, pH 7).The homogenate was diluted to 10-5 and which allows us to have a preliminary understanding of inoculated into 2 Petri dishes containing MRS-agar the safety, origin, habitat, and physiological medium and incubated under anaerobic and aerobic characteristics of a microorganism, correctly isolating conditions for 24-48 hours at 37-40°C.The isolated the strain at the species level.Lactobacteria are one of isolates were characterized according to their the most studied representatives of the SAB group, morphological, cultural, physiological, and biochemical along with streptococci, lactococci, and properties according to the indicators specified in the enterococci.According to the modern phylogenetic "Bergji spectrometer".Samples with rod-shaped and classification of bacteria, the genus Lactobacillus has blue cells under the microscope, Gram-negative and more than one hundred and fifty species and catalase-negative, were selected and cultured on MRS- subspecies.Using 16S rRNA gene sequencing, the broth medium (HiMedia, India). researchers identified 14 isolates of SABs as: