Mitochondrial genome from the facultative anaerobe and petite-positive yeast Dekkera bruxellensis contains the NADH dehydrogenase subunit genes.

The progenitor of the Dekkera/Brettanomyces clade separated from the Saccharomyces/Kluyveromyces clade over 200 million years ago. However, within both clades, several lineages developed similar physiological traits. Both Saccharomyces cerevisiae and Dekkera bruxellensis are facultative anaerobes; in the presence of excess oxygen and sugars, they accumulate ethanol (Crabtree effect) and they both spontaneously generate respiratory-deficient mutants (petites). In order to understand the role of respiratory metabolism, the mitochondrial DNA (mtDNA) molecules of two Dekkera/Brettanomyces species were analysed. Dekkera bruxellensis mtDNA shares several properties with S. cerevisiae, such as the large genome size (76 453 bp), and the organization of the intergenic sequences consisting of spacious AT-rich regions containing a number of hairpin GC-rich cluster-like elements. In addition to a basic set of the mitochondrial genes coding for the components of cytochrome oxidase, cytochrome b, subunits of ATPase, two rRNA subunits and 25 tRNAs, D. bruxellensis also carries genes for the NADH dehydrogenase complex. Apparently, in yeast, the loss of this complex is not a precondition to develop a petite-positive, Crabtree-positive and anaerobic nature. On the other hand, mtDNA from a petite-negative Brettanomyces custersianus is much smaller (30 058 bp); it contains a similar gene set and has only short intergenic sequences.