Rapid purification of yeast mitochondrial DNA in high yield

A procedure is presented for the rapid isolation of mitochondrial DNA (mtDNA) in high yield from Saccharomyces cerevisiae. Yeast cells, which may be grown to late stationary phase, are broken by a combination of enzymatic and mechanical means; mtDNA is then isolated from a crude mitochondrial lysate by a single cycle of bisbenzimide-CsCl buoyant density centrifugation. mtDNA so isolated is at least 99.5% pure, and has a mean duplex molecular weight of 24.5 . 10(6). In addition to mtDNA and bulk nuclear DNA, several other yeast nucleic acid species, identified as ribosomal DNA and a mixture of duplex RNAs, form discrete bands in these gradients.