Food Control of Probiotic Lactobacillus delbruekii ssp. bulgaricus in Most Frequently Consumed Bulgarian Yogurts

The most prominent probiotics are the lactic acid bacteria (LAB). They synthesize vitamins, enzymes, and other bioactive compounds valuable for human health. LAB are known to considerably boost the immune system. Besides, LAB shows strong bactericidal and antifungal properties. The most valuable feature contributing to human longevity remains their ability to break the xenobiotics. Our study aimed to evaluate the content of the probiotic bacterium Lactobacillus delbruekii ssp. bulgaricus in most frequently consumed by Bulgarians yogurts. We analysed six yogurt samples of 3.6% cow milk studying the amount of lactobacilli, and lactic acid content, and performed morphological, biochemical tests and SEM microscopy of Lactobacillus bulgaricus isolates. Our results showed that the number of lactobacilli per gram in all yogurt samples, except one, meets the Bulgarian and EU standards. Five samples contained the optimal for therapeutic use L. bulgaricus, from 2.6x106 to 7.1x107 LAB/g yogurt, and one was under the recommended values consisting of 0.7x106 of LAB or 300 000 CFU/g below the standards. 12 LAB isolates were taxonomically identified as L. delbrueckii ssp. bulgaricus based on morphological, biochemical, and SEM analysis. During SEM analysis the unique and very rare Y-shape of the L. bulgaricus rods was observed.