Bacterial diversity of traditional fermented milks from Cameroon and safety and antifungal activity assessment for selected lactic acid bacteria

Abstract

Fermented milks play a major role in human diets worldwide. Lactic acid bacteria are the main microorganisms involved and often added as starters. However, use of autochthonous LAB strains for directed fermentations demands caution due to their potential to produce undesirable metabolites or harbor antibiotic resistance genes. The aim of this study was to evaluate bacterial diversity of two traditional Cameroonian fermented milks (Pendidam and Kindirmou) and characterize selected LAB strains safety and antifungal activity. Microbial analyses revealed that LAB, fungi and total viable bacteria were dominant, followed by coliforms and Staphylococcus spp. LAB isolates were screened for acidic and bile salt tolerances and 38% exhibited survival rates higher than 60% in both conditions. These isolates were then clustered using M13-PCR and representative strains identified via gene sequencing. Identified species corresponded to Pediococcus acidilactici (68.6%), Lactobacillus fermentum (28.6%) and Lactobacillus plantarum (2.8%). Representative isolates were screened for biogenic amine genes, ATB resistances and antifungal activities. Seven P. acidilactici and 1 L. fermentum were positive for the agdi gene while none of the 12 retained strains showed resistances to ATB, except vancomycin and kanamycin. L. plantarum KE04 and L. fermentum PE172 exhibited interesting antifungal activities.