Aims: The diversity of the surface flora of two French red-smear soft cheeses was examined by cultivation-dependent and cultivation-independent methods to assess their composition and to evaluate the accuracy of both approaches. Methods and Results: Culture-independent methods used involved 16S ribosomal DNA gene cloning and sequencing and single-strand conformation polymorphism analysis (SSCP). The culture-dependent method used involved direct culture and macroscopic observation, polymerase chain reaction of the 16S rRNA gene from DNA extracted from single colonies followed by complete sequencing of the gene. Only few species were recovered by both approaches either in the pasteurized and the farmer cheese. A large diversity of isolates or 16S rDNA sequences related to marine bacteria was identified at the surface of both cheeses. Conclusions: The results indicated that all three techniques were informative and complementary to allow a more accurate representativeness of the cheese surface biodiversity. Significance and Impact of the Study: Cultivation and molecular methods have to be combined in order to obtain an extended view of the bacterial populations of complex ecosystems.

Enzymatic activities that could be involved in methanethiol generation in five cheese-ripening bacteria were assayed, and the major sulfur compounds produced were identified. l -Methionine and α-keto-γ-methyl-thio-butyric acid demethiolating activities were detected in whole cells and cell extracts (CFEs) of all the bacteria tested. No l -methionine deaminase activity could be detected in any of the ripening bacteria and l -methionine aminotransferase was detected in CFEs of Brevibacterium linens , Micrococcus luteus , and Corynebacterium glutamicum . The results suggest that several pathways for l -methionine catabolism probably coexist in these ripening bacteria.