Abstract
BackgroundCorynebacterium variabile is part of the complex microflora on the surface of smear-ripened cheeses and contributes to the development of flavor and textural properties during cheese ripening. Still little is known about the metabolic processes and microbial interactions during the production of smear-ripened cheeses. Therefore, the gene repertoire contributing to the lifestyle of the cheese isolate C. variabile DSM 44702 was deduced from the complete genome sequence to get a better understanding of this industrial process.ResultsThe chromosome of C. variabile DSM 44702 is composed of 3, 433, 007 bp and contains 3, 071 protein-coding regions. A comparative analysis of this gene repertoire with that of other corynebacteria detected 1, 534 predicted genes to be specific for the cheese isolate. These genes might contribute to distinct metabolic capabilities of C. variabile, as several of them are associated with metabolic functions in cheese habitats by playing roles in the utilization of alternative carbon and sulphur sources, in amino acid metabolism, and fatty acid degradation. Relevant C. variabile genes confer the capability to catabolize gluconate, lactate, propionate, taurine, and gamma-aminobutyric acid and to utilize external caseins. In addition, C. variabile is equipped with several siderophore biosynthesis gene clusters for iron acquisition and an exceptional repertoire of AraC-regulated iron uptake systems. Moreover, C. variabile can produce acetoin, butanediol, and methanethiol, which are important flavor compounds in smear-ripened cheeses.ConclusionsThe genome sequence of C. variabile provides detailed insights into the distinct metabolic features of this bacterium, implying a strong adaption to the iron-depleted cheese surface habitat. By combining in silico data obtained from the genome annotation with previous experimental knowledge, occasional observations on genes that are involved in the complex metabolic capacity of C. variabile were integrated into a global view on the lifestyle of this species.
Highlights
Corynebacterium variabile is part of the complex microflora on the surface of smear-ripened cheeses and contributes to the development of flavor and textural properties during cheese ripening
It was supposed that the coryneform species Brevibacterium linens represents the major organism on the surface of smear-ripened cheeses [9], but recent investigations emphasized the importance of other coryneform bacteria to the ripening process and identified Arthrobacter nicotianae, Arthrobacter arilaitensis, Brevibacterium ammoniagenes, Microbacterium gubbeenense, Rhodococcus fascians, and members of the genus Corynebacterium (Corynebacterium ammoniagenes, Corynebacterium casei, and Corynebacterium variabile) dominating the microflora of Gubbeen, Tilsit, and other smear-ripened cheeses [10,11,12,13,14]
We reconstructed in this study the metabolic capabilities of C. variabile DSM 44702 from the complete genome sequence to understand its adaptation to the cheese surface habitat and its physiological role in cheese ripening and flavor generation
Summary
Corynebacterium variabile is part of the complex microflora on the surface of smear-ripened cheeses and contributes to the development of flavor and textural properties during cheese ripening. The bacterial microflora dominating the later stages of ripening of smear-ripened cheeses is composed of salt-tolerant micrococci, staphylococci, and corynebacteria [2,8]. It was supposed that the coryneform species Brevibacterium linens represents the major organism on the surface of smear-ripened cheeses [9], but recent investigations emphasized the importance of other coryneform bacteria to the ripening process and identified Arthrobacter nicotianae, Arthrobacter arilaitensis, Brevibacterium ammoniagenes, Microbacterium gubbeenense, Rhodococcus fascians, and members of the genus Corynebacterium (Corynebacterium ammoniagenes, Corynebacterium casei, and Corynebacterium variabile) dominating the microflora of Gubbeen, Tilsit, and other smear-ripened cheeses [10,11,12,13,14]
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