Abstract : The objective of this work was to study a cheese-ripening bacterium: Brevibacterium aurantiacum (BA). Molecular tools were developed to study the biodiversity of the genus Brevibacterium. The MLST approach with 9 housekeeping genes is a promising new tool for identifying Brevibacteriaceae. We have found a new species belonging to the strains of technological interest: B. antiquum. Using DNA microarray, the results show that 13% and 15% of the genome sequenced strain ATCC 9174 are absent and / or divergent in the strains ATCC 9175 and BL2. We then conducted a reconstruction of sulfur metabolism in B. aurantiacum ATCC 9175 and studied its regulation in the presence of different sulfur sources using omics techniques. The results showed that the sulfate assimilation pathways and the biosynthesis of cysteine were repressed in the presence of cystine and that the biosynthetic pathways of methionine via homocysteine together with the transulfuration pathway were down-regulated by methionine. Finally, when we add methionine in the medium, we observed a coordinated induction of genes encoding for a methionine gamma-lyase and a methionine transporter, suggesting the presence of a specific regulator for this pathway. Finally, we studied the behavior of BA in the presence or absence of the cheese-ripening yeast Kluyveromyces lactis by physiological, biochemical and transcriptomic approaches. In BA, we observed changes in the carbon and nitrogen metabolism and the biosynthesis of pigments when cultived in co-culture with K. lactis.