IDENTIFICAÇÃO DA POPULAÇÃO MICROBIANA DO KEFIR

INTRODUCTION: Kefir is a slightly effervescent fermented beverage with an alcohol content between 0.5% and 1.5%. It is rich in bioactive compounds, including lactic acid bacteria (LAB), acetic acid bacteria, and yeasts, forming a complex symbiotic system with proven health benefits such as digestion normalization and immune stimulation. This study aims to identify the microbial populations of kefir using phenotypic and genotypic methods, including 16S rRNA gene sequencing for a detailed analysis of microbial diversity. The detailed identification of the isolates is crucial for the future approval by regulatory agencies. Molecular methods are he one of choice for that purpose. AIMS: The objective is to identify and characterize the microbial populations of kefir, optimizing DNA extraction and amplification techniques using PCR-RAPD methods and phenotypic tests. MATERIALS AND METHODS: Serial dilutions, agar isolations, and the creation of an isolate bank were performed for sample collection. Screening included PCR-RAPD and phenotypic tests (catalase, oxidase, Gram staining, and hemolytic activity). Three DNA extraction methods were tested: phenol-chloroform, thermal shock, and urea, with the latter being the most efficient in obtaining DNA. RESULTS: The urea-based extraction method proved superior, providing suitable DNA for PCR. PCR-RAPD analysis and phenotypic tests helped identify isolates, excluding pathogenic strains and optimizing strain selection for future studies. The amplification sequencing of DNA from isolates will warrant the appropriate identification of bacteria with the desired probiotic characteristics. FINAL CONSIDERATIONS: Future complementary studies should provide for isolates with probiotic proporties, thus making new therapeutical alternatives for various diseases, reinforcing the contribution of fermented beverages for human health.

KEYWORDS: 1. Kefir; 2. Microbial population; 3. Genetic identification; 4. DNA extraction; 5. Phenotypic tests.