Preservative potentials and stability of bacteriocin-producing lactic acid bacteria of dairy origins

Background: Lactic acid bacteria (LAB) from dairy sources are known to produce bacteriocins with promising antimicrobial properties. The variations in their preservative effectiveness and stability under different environmental conditions create a gap in knowledge. This study aimed to produce bacteriocin and determine their stability properties of bacteriocin isolated from lactic acid bacteria indigenous to selected fermented diary (cheese and ‘Nunu’) within Ilorin metropolis.Methodology: Isolation and identification of bacteriocin-producing lactic acid bacteria (LAB) from fermented dairy products and bacteriocin purification, were carried out by standard methods. Bacteriocin stability tests were performed and characterized by heat resistance, sensitivity to pH and proteolytic enzyme by the method described by Gautam and Sharma. Bio-preservation efficacy of bacteriocin was evaluated through microbial load determination of the food products after treatment with purified bacteriocin, with and without refrigeration. Molecular identification of the bacteriocin-producing LAB was determined by 16S rRNA sequencing.Results: Four LAB were isolated from the food products and phenotypically identified as Lactobacillus spp and Streptococcus spp. The bacteriocin-producing LAB were identified by 16s RNA sequencing as Lactobacillus fermentum strain TSGB1241, Lactococcus fermentum strain DMF18, Lactococcus lactis subsp cremoris and Pediococcus pentosaceus SL4. The antibacterial activity of bacteriocin produced by the LAB was affected by an increase temperature and maximum activity was recorded at acidic pH (2.0-4.0), which indicates its potential use in acidic food. The antibacterial activity was completely lost during treatment with proteolytic enzyme (pepsin). The preservative test showed the potential of refrigerated bacteriocin to reduce microbial load that may contaminate stored food products.Conclusion: Bacteriocin produced from cheese and ‘Nunu’ offer bio-preservative efficacy and provide stability to intrinsic and extrinsic factors that can affect food spoilage. This bacteriocin offers natural and safe and effective preservation to foods products.