Diversity, phylogenetic relationship and antibacterial potential of Bifidobacterium species isolated from raw milk production chain in Abidjan (Côte d'Ivoire)

The local dairy commodity, from farm to retail point, is informal and often escapes safety surveillance
and results in high contamination of local milk by pathogens. The objective of this study was to
determine the biodiversity of Bifidobacterium species in the informal dairy production chain in Abidjan
and evaluate their potential antibacterial activity against pathogens. Bifidobacterium species were
identified after sequencing of hsp60 genes. Results showed that Bifidobacterium were present in 9% of
samples. Milkers' hands (14%) and cows’s udders (14%) were the most contaminated with
Bifidobacterium. These isolates belong to five different species. Most Bifidobacterium isolated are
Bifidobacterium minimum (53%) and Bifidobacterium pseudolongum subsp. Globosum (24.4%). The
other strains are composed of one strain of Bifidobacterium thermophilum, Bifidobacterium
thermacidophilum subsp. suis and Bifidobacterium magnum. The isolated Bifidobacterium species
have antibacterial activities that are not related to bacteriocins production, but to organic acids
production (65%), which exert in vitro inhibitory action against Listeria monocytogenes, Salmonella
hadar and Salmonella typhimurium, Staphylococcus aureus, Escherichia coli O27 and Escherichia coli
O157H7. However, ensuring milk safety along the local milk production chain requires implementation
of good hygiene practices together with adapted technology, such as fermentation.