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.

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).

Ozonation of sunflower oils: impact of experimental conditions on the composition and the antibacterial activity of ozonized oils.

Ozone can react with vegetable oils to produce ozonized oils which have antimicrobial properties and can be used in dermatology. The aim of this study was to evaluate the influence of ozonation conditions and of the initial fatty acid composition on iodine index (II), peroxide index (IP), acidity value (AV) of ozonized sunflower oils. The antibacterial activity of these products against the three bacterial strains that are more often involved in mastitis (Staphylococcus aureus, Escherichia coli and Streptococcus uberis) was also evaluated. In that purpose, two different sunflower oils have been studied: a "classical" oil (55% linoleic acid, 35% oleic acid) and a "high oleic" oil (90% oleic acid). Both were ozonized with or without water during different times (from 1 to 7 h). Results show that the addition of water has a direct impact on the increase in IP (up to 2600 meq of active oxygen/kg of oil with water and 430 without) and AV but does not influence the kinetic of the decrease in II. Minimal inhibitory concentrations were ranging from 1.25 to 40 mg/mL and the antibacterial activity of oils ozonized with water was better than the one of oils ozonized alone. These results are an open door to new applications of ozonized oils.