Contaminant yeast detection in industrial ethanol fermentation must by rDNA-PCR

AIMS: The present work focuses on the possibility to use conserved primers that amplify yeast ITS1-5.8S-ITS2 ribosomal DNA locus (rDNA) to detect the presence of non-Saccharomyces cerevisiae yeast in fermentation must of bioethanol fermentation process. METHODS AND RESULTS: Total DNA was extracted from pure or mixed yeast cultures containing different cell concentrations and different contaminant/fermenting yeast concentrations and submitted to PCR. Upon improvement of detection limits and DNA extraction protocol, must samples of distillery were checked for the presence of contaminant yeast. Contaminant rDNA bands were detected only in industrial samples during contamination episodes, but not in noncontaminated must. CONCLUSIONS: The method described here could detect the presence of contaminant yeast from industrial must in eight hours after sampling. SIGNIFICANCE AND IMPACT OF THE STUDY: The improved procedure may help to avoid severe contamination episodes at fermentation industries by decreasing the detection time from 5 days to 8 h and possible quantification of contaminant yeasts that can impose economical loss to the process.