Eliminate ‘enemy’ yeast

Yeasts are a group of predominantly unicellular fungi which mankind has exploited in food and beverage production for millennia.

The best known is the baking yeast Saccharomyces cerevisiae but more than a thousand other species have been described worldwide.

Among these are a sub-group of contaminant yeast species causing product spoilage and major economic losses in a variety of industrial sectors. Yeast’s wide environmental occurrence and high tolerance to manufacturing stresses, coupled with decreasing acceptability of chemical preservatives and global environmental changes favouring fungal growth, mean that they pose a serious and continuing threat.

Fortunately, help is at hand. Recent progress in DNA analysis has enabled rapid, accurate yeast identification methods to be developed. Armed with precision identification (as opposed to simple colony counts) it is possible to predict and eliminate the source of contamination.

Furthermore, advances in genomics mean that databases containing whole genome sequences are expanding. These resources can be mined for information relevant to understanding how defences were breached in the first place. Similarly, the recent development of comprehensive metabolic profiling (‘metabolomics’) provides further information on chemical properties resulting in product spoilage. New yeast testing methods of this nature are invaluable in countering the ongoing threat.

National Collection of Yeast Cultures is based in Colney, Norwich. www.ncyc.co.uk

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