Determination of Survivability of Some Probiotic Lactic Acid Bacteria in Some Locally Produced Drinks

Abstract

Foods are not only intended to placate hunger and supply essential nutrients but also to prevent the nutrition-related diseases and to improve physiological and mental wellbeing of consumers. This led to the development of probiotic foods. Probiotics are said to be live microorganisms which when adequately (10⁶/10⁷ CFU/mL) administered confer health benefits to the host. Probiotic drinks both dairy and non-dairy have been found to be carriers of these organisms to their site of action. This research aims at determining the survivability of probiotic lactic acid bacteria in some locally produced drinks. The isolation of the organisms from yoghurt and “nono” were conducted using cultural methods and further characterized using biochemical tests. Cell surface hydrophobicity (CSH), cellular auto-aggregation assays (CAA), hemolytic activities, bile salt and NaCl tolerance test were conducted to determine the probiotic properties of the organisms. The survivability of the organisms was evaluated after standardizing the inoculum using 0.5 McFarland standard and then serial dilution, plating and counting of visible colonies. Results were analyzed by ANOVA using SPSS software version 20.0. Out of the ten isolated and biochemically characterized lactic acid bacteria, three Lactobacillus species showed probiotic status, with CSH values of (79%, 75.2% and 91.3%) and CAA index of (79.3%, 74% and 83.5%), respectively, however there is no statistically significant difference between the CAA and CSH values of the isolates (p = 0.13 and p = 0.5, respectively), which indicates that all the isolates had approximately equal probiotic capabilities. “Kunun zaki” showed the highest survivability rate with the probiotic status being maintained for three days, and counts ranging from 1.4 to 1.05 x 10⁶ CFU/mL; whereas “zobo” showed the least duration as a probiotic (one day, and a count of 1.16 x 10⁶ CFU/mL. There is a significant difference (p=0.02) in the growth of the organisms over the incubation period (5 days), however, there is no significant difference (p=0.82) between the growth of the organisms growing on different drinks, indicating that time after incubation is the critical determinant of probiotic status, and that the isolates can grow equally well in all the drinks tested. This research reported the isolation of Lactobacillus species confirmed to be probiotics from yoghurt and “nono”. Enumeration of probiotic LAB in all the drinks revealed the drinks were probiotic containing 10⁶ CFU/mL for two (2) days with the exception of “Kunun zaki” that reached up to three (3) days as a probiotic drink. The pH level of all the drinks decreased and the drinks became acidic (pH range 6.0-1.8).