Comparative studies of the antimicrobial, antioxidant activities, vitamins, organic acid and short-chain fatty acids of postbiotics derived from five probiotic strains.

The current study was conducted to determine and investigate the properties of postbiotics like antimicrobial activity, antioxidants, vitamins, organic acids, and short-chain fatty acids produced by some probiotics. The antimicrobial activity of all postbiotics from tested probiotic strains showed antimicrobial effects against most indicator strains. All tested strains showed a high inhibition zone against C. albicans and ranged from 13.5 to 27 mm. The results show that L. acidophilus and L. helveticus had the largest inhibitory effects on tested pathogenic bacteria and fungi. Furthermore, the results show that the postbiotics of all probiotics have antioxidant activity, and the L. plantarum strain had the highest antioxidant activity 234.38μg TE/ml, followed by L. rhamnosus GG 229.52μg TE/ml and B. bifidum 227.58μg TE/ml. On the other hand, the results indicated that postbiotics produced by various strains contain many organic acids in different concentrations, and butyric acid was not detected in all postbiotics of the tested strains. In addition, different amounts of vitamin B group (µg/ml) were detected in all tested postbiotics, and vitamin B6 was the highest vitamin produced by all probiotic strains in the study. Therefore, our findings suggest that the novel postbiotic compounds detected in this study are in preparation for the next research on their nutritional evaluation to identify the best strains used as potential functional dairy products.