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S. In all, 4379 isolates from 35 products, including 24 artisanal cheeses, were surveyed with a view to identifying strains that could be used as starters in commercial dairy fermentations. Of the isolates, 38 % were classified as Lactococcus, 17 % as Enterococcus, 14% as Streptococcus thermophilus, 12 % as mesophilic Lactobacillus, 10% as Leuconostoc and 9 % as thermophilic Lactobacillus. Acid production by the isolates varied considerably. Of the 1582 isolates of Lactococcus and 482 isolates of mesophilic Lactobacillus tested, only 8 and 2 % respectively produced sufficient acid to lower the pH of milk to 5n3 in 6 h at 30 mC. In contrast, 53, 32 and 13 % of Str. thermophilus, thermophilic Lactobacillus and Enterococcus isolates respectively reduced the pH to 5n3. These isolates were found only in some French, Italian and Greek cheeses. Bacteriocins were produced by 11 % of the 2257 isolates tested and 26 of them produced broad-spectrum bacteriocins which inhibited at least eight of the ten target strains used, which included lactic acid bacteria, clostridia and Listeria innocua. The most proteolytic of the 2469 isolates tested wereStr. thermophilus from Fontina cheese followed by Enterococcus from Fiore Sardo and Toma cheese and thermophilic Lactobacillus from all sources. Exopolysaccharides were produced by 5n3 % of the 2224 isolates tested.In many Southern European countries cheeses are made from cows', goats', ewes'

The bacteria on the surface of a farmhouse smear-ripened cheese at four stages of ripening (4, 16, 23, and 37 days) from inoculated (i.e., deliberately inoculated with Brevibacterium linens BL2) and noninoculated (not deliberately inoculated with B. linens BL2) cheese were investigated. The results show that, contrary to accepted belief, B. linens is not a significant member of the surface flora of smear cheese and no microbial succession of species occurred during the ripening of the cheeses. Of 400 isolates made, 390 were lactate-utilizing coryneforms and 10 were coagulase-negative Staphylococcus spp. A detailed analysis of the coryneforms was undertaken using phenotypic analysis, molecular fingerprinting, chemotaxonomic techniques, and 16S rRNA gene sequencing. DNA banding profiles (ramdom amplified polymorphic DNA [RAPD]-PCR) of all the coryneform isolates showed large numbers of clusters. However, pulsed-field gel electrophoresis (PFGE) of the isolates from the cheeses showed that all isolates within a cluster and in many contiguous clusters were the same. The inoculated and noninoculated cheeses were dominated by single clones of novel species of Corynebacterium casei (50.2% of isolates), Corynebacterium mooreparkense (26% of isolates), and Microbacterium gubbeenense (12.8% of isolates). In addition, five of the isolates from the inoculated cheese were Corynebacterium flavescens. Thirty-seven strains were not identified but many had similar PFGE patterns, indicating that they were the same species. C. mooreparkense and C. casei grew at pH values below 4.9 in the presence of 8% NaCl, while M. gubbeenense did not grow below pH 5.8 in the presence of 5 to 10% NaCl. B. linens BL2 was not recovered from the inoculated cheese because it was inhibited by all the Staphylococcus isolates and many of the coryneforms. It was concluded that within a particular batch of cheese there was significant bacterial diversity in the microflora on the surface.The most significant period of cheese production is probably the ripening process, during which starter and nonstarter bacteria, chymosin, and the indigenous milk enzymes develop the organoleptic and textural properties of the cheese. This is particularly true for surface-ripened cheese, due to the variety and abundance of microorganisms on its surface. Surface-ripened cheeses can be divided into mold ripened, e.g., Camembert and Brie, and bacteria ripened, e.g., Limburger, Tilsit, Brick, and Münster. The latter cheeses are sometimes called washed-rind cheeses because of the extensive washing given to the surfaces of these cheeses during ripening. They are also called smear cheeses, because of the glistening appearance of the surface, or red-smear cheeses, due to the production of a red carotinoid by Brevibacterium linens, which is thought to be the most common bacterium occurring on the surface of the cheese. For this reason, B. linens is often deliberately inoculated onto the surface of the cheese during the early days of ripening, either as a commercial preparation or a...

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