title: Phenotypic and genotypic characterization of lactic acid bacteria isolated from raw goat milk and effect of farming practices on the dominant species of lactic acid bacteria.
abstract: Lactic acid bacteria, in particular Lactococcus lactis, play a decisive role in the cheese making process and more particularly in lactic cheeses which are primarily produced on goat dairy farms. The objective of this study was therefore to identify the main lactic acid bacteria found in raw goats' milk from three different regions in France and evaluate if certain farming practices have an effect on the distribution of species of lactic acid bacteria in the various milk samples. Identification at genus or species level was carried out using phenotypic tests and genotypic methods including repetitive element REP-PCR, species-specific PCR and 16S rRNA gene sequencing. The distribution of the main bacterial species in the milk samples varied depending on farms and their characteristics. Out of the 146 strains identified, L. lactis was the dominant species (60% of strains), followed by Enterococcus (38%) of which Enterococcus faecalis and Enterococcus faecium. Within the species L. lactis, L. lactis subsp lactis was detected more frequently than L. lactis subsp cremoris (74% vs. 26%). The predominance of L. lactis subsp cremoris was linked to geographical area studied. It appears that the animals' environment plays a role in the balance between the dominance of L. lactis and enterococci in raw goats' milk. The separation between the milking parlor and the goat shed (vs no separation) and only straw in the bedding (vs straw and hay) seems to promote L. lactis in the milk (vs enterococci).
authors.affiliation: Université de Toulouse, Ecole d'Ingénieurs de Purpan, 75, voie du TOEC, BP 57611, F-31076 Toulouse Cedex 03, France. Electronic address: helene.tormo@purpan.fr.
authors.forename: Hélène
authors.initials: H
authors.lastname: Tormo
authors.affiliation: Université de Toulouse, Ecole d'Ingénieurs de Purpan, 75, voie du TOEC, BP 57611, F-31076 Toulouse Cedex 03, France.
authors.forename: Djamila
authors.initials: D
authors.lastname: Ali Haimoud Lekhal
authors.affiliation: Université de Toulouse, UPS, Lab Genie Chim, F-31 062 Toulouse, France.
authors.forename: C
authors.initials: C
authors.lastname: Roques
mesh_terms: D000818:Animals; D002611:Cheese / Q000382:microbiology; D003612:Dairying / Q000379:methods*; D017753:Ecosystem; D016983:Enterococcus / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D005516:Food Microbiology; D005602:France; D005838:Genotype; D006041:Goats; D006799:Housing, Animal / Q000592:standards; D007777:Lactobacillaceae / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D013294:Lactococcus lactis / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D008892:Milk / Q000382:microbiology*; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics
chemical_list: D012336:RNA, Ribosomal, 16S
keywords: 16S rRNA gene sequencing; Enterococcus subsp; Farming practices; Goat milk; Lactococcus lactis; REP-PCR