Technological properties of strains of Enterococcus gallinarum isolated from selected Nigerian traditional fermented foods

Abstract

Aims: Enterococci may be beneficial to health and can be used as starter cultures for fermented foods. Therefore, in this study Enterococci were identified from some Nigerian fermented foods, and their technological properties evaluated in order to gain a better understanding of their usefulness as starter cultures or probiotics. Methodology and results: Five isolates from various Nigerian traditional fermented foods were identified as Enterococcus gallinarum based on phenotypic and genotypic tests. Technological properties were examined and antimicrobial investigations were carried out. Out of the five strains only E. gallinarum W211 and E. gallinarum T71 showed strong acidification, hydrophobicity, lipolysis, proteolysis and tolerance to bile salts. E. gallinarum W211 and E. gallinarum T71 did not produce biogenic amines while the other three strains produced tyramine from tyrosine. Only strains W211 and T71 produced bacteriocin(s), and these were active against 7 and 10 indicator organisms respectively out of 16. The bacteriocin from both strains had a molecular weight of 27KDa and the gene responsible was in each case identified as enterocin P. The bacteriocin was resistant to treatment with catalase, RNase and lysozyme, but activity was lost on treatment with Α-chymotrypsin, trypsin, and proteinase K. Bacteriocin activity survived heating at 100 °C for 30 min. Conclusion, significance and impact of study: Bacteriocinogenic E. gallinarum W211 and T71 have been selected for further characterization of their bacteriocin(s) because these strains exhibited useful probiotic and technological properties pointing to their suitability as candidates for starter cultures in fermentation process.