A rapid method based on mtDNA restriction analysis is described for yeast s
train identification. The method is an adaptation of that devised by Querol
et al. [Syst. Appl. Microbiol. 15 (1992) 439] for Saccharomyces cerevisiae
wine strains, and consists of the standard miniprep isolation of yeast tot
al DNA, and the use of restriction endonucleases that recognise, a large nu
mber of sites in yeast nuclear DNA, but few sites in the mitochondrial DNA.
In the adapted method, the propagation of yeast cells and restriction anal
ysis were the steps mainly affected: cell growth was reduced to 36 h by usi
ng microfuge tubes, and the restriction analysis was carried out in just 33
min using a microwave oven for DNA digestion, and minigels for restriction
fragment separation. The DNA extraction procedure was performed in the sam
e way as in the original protocol, but slightly reducing the duration of ea
ch step and scaling down the volumes of the different solutions, enzymes an
d reagents used. As result, a large time reduction (52.5 h) was obtained co
mpared to the original method. The DNA obtained can be directly digested wi
th endonucleases displaying clear restriction patterns useful for S. cerevi
siae yeast strain differentiation. In addition, strains belonging to other
foodborne yeast species, including spoilage yeast species, can also be iden
tified. (C) 2001 Elsevier Science B.V. All rights reserved.