BIO-PRESERVATION OF BEEF USING LACTIC ACID BACTERIA ISOLATED FROM NONO SOLD IN SAMARU ZARIA, NIGERIA

Abstract

This study explores the use of probiotic Lactic Acid Bacteria isolated from ‘Nono’, a traditional fermented milk, as natural bio-preservatives for beef. The increasing interest in sustainable food preservation methods has led to research on alternatives that minimize chemical preservative use. The proximate composition of the ‘Nono’ sample revealed significant deviations from Codex standards. Notably, the ‘Nono’ had lower moisture content (59.84% ± 0.9%) but higher levels of ash (3.65% ± 0.1%), fat (16.25% ± 0.09%), protein (7.00% ± 0.29%), and carbohydrates (13.26% ± 3.38%). Six LAB isolates (N1, N2, N3, N4, N5 and N6) were isolated from the ‘Nono’ sample and were subjected to probiotic screening. Acid tolerance tests showed that isolates N2, N3, N4, and N6 survived well in highly acidic environments (pH 2.0, 3.0, and 4.0), while N1 and N5 did not tolerate the acidic conditions, suggesting their limited probiotic efficacy. In addition, adherence tests further revealed that N2, N3, N4, and N6 demonstrated strong colonization potential, an essential feature for probiotics to exert their beneficial effects in the gut. The antibacterial activity of the three probiotic LAB (N2, N4 and N6) isolates was also assessed. N4 demonstrated the strongest broad-spectrum antibacterial activity, with zone of inhibition of 14 mm against Pseudomonas sp while Staphylococcus aureus, Escherichia coli and Salmonella sp had 13 mm zone of inhibition each respectively. N2 exhibited moderate activity with zone of inhibition ranging between 12mm-14mm across all tested pathogens, while N6 recorded the least antibacterial activity with zone of inhibition ranging between 10mm-12mm. Based on these screening, isolates N2, N4, and N6 were selected based on their promising probiotic properties. Analysis of 16S rRNA gene sequences of the four selected isolates using NCBI blast and subsequently phylogenetic analysis revealed that N2, N4 and N6 were identified as Limosilactobacillus fermentum strain HYLF N2 PQ136030.1, Limosilactobacillus fermentum strain HYLF N4 PQ144862.1, Limosilactobacillus fermentum strain HYLF N6 PQ144887.1. Further investigation into the bio-preservative potential of these isolates revealed that Limosilactobacillus fermentum strain HYLF N2 PQ136030.1, Limosilactobacillus fermentum strain HYLF N4 PQ144862.1, Limosilactobacillus fermentum strain HYLF N6 PQ144887.1. significantly reduced bacterial counts in the preserved beef during the first three days of storage, particularly at higher volume of 80 µl, where bacterial counts dropped to 1.1 × 10⁵ CFU/g. However, by Day 5, bacterial growth became too numerous to count, indicating that while these strains exhibit strong initial bio-preservative effects, their effectiveness diminishes over time. The declining efficacy over time suggests the need for optimized concentrations or combining these strains with other preservation methods to enhance long-term preservation.

Keywords: Bio-preservation, Lactic Acid Bacteria, Beef, Limosilactobacillus fermentum, Probiotics, ‘Nono’, Nigeria