iIn Vitro/iScreening and Selection of Probiotic Lactic Acid Bacteria Isolated from Spontaneously Fermenting Kunu-Zaki

摘要

The present study was conducted to determine the pro-biotic properties in vitro of the lactic acid bacteria isolated from spontaneously fermenting kunu-zaki. Kunu-zaki was processed using composite, non composite, germinated and ungerminated Digitaria exilis (Fonio), Sorghum bicolor (Sorghum) and Pennisetum americanum (Millet) cereals. A total of 150 LAB isolates were obtained from all the fermenting slurries. These 150 LAB isolates were screened for their ability to grow at pH 3.0, resistance against bile salt and ability to inhibit reference test pathogens. Out of these 150 LAB isolates;21 exhibited good probiotic properties. All the 21 isolates were further identified to specie and subspecies level using standard API50CHL system with all 21 showing good survival (P < 0.05) in a pH 3.0 buffered medium and subsequent resistance to 0.3% bile. The LAB isolates which survived these conditions consisted of 18 Lactobacillus species, 2 Pediococcus species and 1 Lactococcus specie. These LAB species were further examined for antimicrobial activity against the growth of reference pathogens Staphylococcus aureus 25923, Escherichia coli 25922, Pseudomonas aeruginosa 27853 and Enterococcus faecalis 29212. All 21 LAB species exhibited good inhibition of all test reference pathogens except Lactobacillus fructivorans, Lactococcus lactis sp lactis and L. fermentum which however, showed no zone of inhibition against the growth of E. faecalis. Kunu-zaki made from composite un-germinated Sorghum bicolor (Sorghum) and Pennisetum americanum (Millet) cereal grains contained the highest percentage (52%) of LAB species which showed good probiotic criteria in vitro. Non composite ungerminated cereals accounted for 33% of the total probiotic LAB isolates whilst the germinated non composite and composite cereals recorded the lowest percentage (10%) and (5%) of probiotic LAB respectively. The results of this research study showed that the LAB species isolated from wild fermentation of kunu-zaki beverage fulfilled the criteria for in vitro screening of probiotic characteristics. These LAB species possed potential for further use as probiotic in human preparations and suggested the use of kunu-zaki made from ungerminated composite sorghum and millet grains as a natural probiotic drink.