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

Abstract

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 Bifidobacteriumminimum (53%) and Bifidobacterium pseudolongum subsp. Globosum (24.4%). The other strains are composed of one strain of Bifidobacterium thermophilum, Bifidobacteriumthermacidophilum subsp. suis and Bifidobacterium magnum. The isolated Bifidobacteriumspecies 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. Key words: Bifidobacterium, antibacterial, milk, pathogens, Abidjan.