SAFETY PROFILE OF MICROORGANISMS ISOLATED FROM KOMBUCHA

Kombucha is a fermented beverage well recognized for its beneficial health properties. It is produced by the fermentation of plant substrates by a Symbiotic Culture of Bacteria and Yeasts (SCOBY), forming a beverage with a complex matrix rich in bioactive compounds and diversified microbial composition. The increase in its consumption has driven scientific research on the diversification of substrates and the optimization of its microbiological composition for the development of new products. However, safety aspects are little discussed. Thus, this study aimed to evaluate the microbiological safety of lactic acid bacteria, acetic bacteria and yeasts isolated from different kombucha beverages produced from the fermentation of green tea, black tea and coffee infusion by symbiotic culture of household origin. The safety profile was analyzed by testing hemolytic activity, and resistance to antibiotics and antifungals. Hemolytic activity was defined by observing hemolysis on sheep blood agar (5%). Antimicrobial resistance was determined by the diffusion disc method, using Chloramphenicol (30 μg), Erythromycin (15 μg), Ampicillin (10 μg), Vancomycin (30 μg), Gentamicin (10 μg), Canamycin (30 μg), Streptomycin (10 μg), Clindamycin (2 μg) and Tetracycline (30 μg) for determination in lactic and acetic bacteria, and Amphotericin B (20 μg), Fluconazole (25 μg) and Nystatin (100 U) for yeasts. For these tests, 133 isolates were analyzed, 25 lactic acid bacteria, 11 acetic bacteria and 97 yeasts. Based on the hemolytic activity results, 52% (n=13) of the lactic acid bacteria isolates did not show hemolysis formation. In contrast, hemolysis was observed in 100% (n=11) of the acetic acid bacteria isolates and in 87% (n=85) of the yeast isolates. All lactic acid bacteria exhibited resistance to at least three antibiotics, with a tendency toward resistance to Gentamicin, Kanamycin, and Streptomycin (68%, n=17). The acetic acid bacteria also showed a critical outcome regarding their resistance profile. All isolates were sensitive only to Ampicillin and Tetracycline and resistant to the other tested antibiotics. Yeast isolates were sensitive to Nystatin (n=97); however, 18% (n=18) and 17% (n=17) exhibited resistance to Amphotericin B and Fluconazole, respectively. Little has been discussed regarding the safety of microorganisms present in fermented products and the actual risks they may pose. These results raise an alert and highlight the need for further studies on this subject, particularly concerning antimicrobial resistance profiles.