-The application of defined specific starter strains and their influence on microbiological, biochemical and sensory characteristics were studied during ripening of Venaco cheese, a traditional Corsican raw milk cheese manufactured with goat's or ewe's milk. Three defined starter blends, composed of wild strains of lactic acid bacteria, were tested. The first blend was composed of 2 strains of Lactococcus lactis subsp. lactis (ratio 1:1) and was used as a control. The second was composed of 3 strains, the two Lactococcus strains used in the first starter blend in addition to a strain of Lactobacillus paraplantarum (ratio 2:2:1). The third blend was also composed of 3 strains, the same two lactococci used in the first blend in addition to a strain of Leuconostoc mesenteroides subsp. mesenteroides (ratio 2:2:1). The experiment was carried out, in duplicate, at two cheese dairies. The first dairy transforms raw goat's milk and the second transforms raw ewe's milk. DNA fingerprinting of cheese isolates using the Rep-PCR technique showed that strains inoculated in milk established themselves in cheese. Lactococci and Ln. mesenteroides subsp. mesenteroides strains were present until the end of ripening, while Lb. paraplantarum was detected in cheese only during the first 15 d. Indigenous lactic microflora were found throughout ripening, showing a balance between this microflora and the starter strains. Goat's and ewe's milk cheeses made with Leuconostoc had the highest level of proteolysis, and those made with Lactobacillus, the highest level of lipolysis. These physico-chemical modifications led to significant differences in cheese sensory characteristics assessed by the triangle test.

-Species and strains of lactic acid bacteria (LAB) were tracked within four commercial Comté cheeses manufactured in three factories by genetic characterisation of isolates at nine stages of cheese-making and ripening. They were also tracked in the corresponding raw milks and starter cultures. Ten species were identified: Streptococcus thermophilus, Lactobacillus helveticus, Lactobacillus delbrueckii, Enterococcus sp., Lactobacillus paracasei, Lactobacillus rhamnosus, Lactobacillus fermentum, Lactobacillus plantarum, Pediococcus acidilactici and Lactobacillus zeae. The first four species were found to originate from the starter cultures, whereas the next three originated from raw milk. The first six species were dominant and were each represented in each cheese by eight dominant and up to 42 subdominant strains. Lb. paracasei was the species exhibiting the most strain diversity, from 11 to 15 different strains per cheese, followed by Lb. rhamnosus, from 1 to 7, and all the other species, from 1 to 5. Growth kinetics for the dominant species and strains could be obtained. Patterns of dominant LAB strains, but not species, and LAB dynamics were cheese-specific. The lactic acid microflora was found to be complex within each cheese in terms of number of different species and of different growth kinetics.