Preservative Potential of Partially Purified Bacteriocin Produced by Lactobacillus helveticus in the Preservation of Tigernut Drink

Abstract

Lactic acid bacteria (LAB) produce bacteriocins as one of its primary products of fermentation and they are generally regarded as safe. The research was aimed to test the biopreservative potential of partially purified bacteriocin produce by Lactobacillus helveticus. A total of 20 samples of fermented cow milk were obtained from Wamakko Local Government, Sokoto. de Man, Rogosa and Sharpe (MRS) agar was used to isolate the Lactic acid bacteria and they are identified using Gram-staining, biochemical tests and further confirmed using Polymerase chain reaction (PCR) and Sanger sequencing methods. Agar well diffusion assay was used to determine the bacteriocin production of the identified LAB and the optimization of the bacteriocin activity at different pH and temperature. Biopresevative potential of bacteriocin in kunun aya was accessed by adding partially purified bacteriocin from Lactobacillus helveticus to the kunun aya and observed for six days.  The LAB isolates identified were  L. Plantarum (3), Pediococcus (4) and  L.casei (1). The molecular method confirmed 2 species of LAB as Lactobacillus plantarum (2) and Lactobacillus helveticus (1). Screening for bacteriocin production shows that 2 strains of L. plantarum and strain of 1 L.casei have the potential to produce bacteriocin. The bacteriocin is active at different pH (2-10) and temperature 30, 50, 70, 90 and 100°C respectively. The assessment of bio-preservation in kunun aya shows that the shelf life of kunun aya was extended at 4°C for five days by addition of D5 (Lactobacillus helveticus) bacteriocin. Isolation of LAB in this fermented food implies that it contains potentially bacteriocin producing LAB which inhibit some food pathogens by extending the shelf life of the kunun aya.