Genotyping by Randomly Amplified Polymorphic DNA of Bacteriocin Producing Lactobacillus acidophilus Strains from Nigeria

Abstract

Yogurt and starter culture producers are still searching strains of Lactobacillus acidophilus to produce healthier yogurt with a longer shelf life and better texture, taste, and quality. This study determined the genotyping of bacteriocin producing Lactobacillus acidophilus strains recovered from Nigerian yogurts. Yogurt samples were collected from four different states of South West regions of Nigeria. Isolates were obtained from MRS Medium and biochemically characterized. This was further confirmed by API50CH. The bacteriocin positivity and activity was determined. Genomic characterization of our Lactobacillus acidophilus strains was done with randomly amplified polymorphic DNA-PCR. All yogurt samples containing Lactobacillus acidophilus strains meet the probiotic requirement of ≥10⁶ cfu/mL. The gel picture revealed 6 RAPD clonal types of Lactobacillus acidophilus strains with RAPD type C observed to be more common. Significant differences existed in the mean growth inhibition zone (t = −7.32, P < 0.05 for E. coli ATCC; t = −6.19, P < 0.05 for E. coli clinical isolates; t = −6.16, P < 0.05 for Enterobacter sp; t = −11.92, P < 0.05 for Salmonella typhi, t = −1.10, P > 0.05 Staphylococcus aureus). No correlation between the bacteriocin production, activity, and their RAPD clonal division (X² = 7.49, P = 0.1610, df = 5). In conclusion, L. acidophilus isolated in Nigeria samples met the probiotic requirements of ≥10⁶ cfu/mL and produce bacteriocins with good spectrum of activity.

Keywords:

• yogurts
• probiotics
• RAPD