Bioluminescent Standard Curves for Quantitive Determination of Yeast Contaminants in Carbonated Beverages

Abstract

The bioluminescent adenosine triphosphate (ATP) assay is a rapid and sensitive tool for quantitating contaminant yeast levels in beverage samples. A simple model system is described for generating standard curves relating yeast ATP to conventional colony forming units (CFUs). Bioluminescent standard curves were generated by spiking commercial cola or diet lemon-lime samples with Saccharomyces rouxii ATCC 36141. Yeast cells were concentrated onto filters under vacuum and ATP was subsequently extracted from the cells for analysis. Correlation coefficients for each S. rouxii standard curve indicated strong linear relationships between ATP and CFU levels (r> 0.90). A composite standard curve (r = 0.97) of data collected from all the S. rouxii-spiked studies predicted yeast levels from spiked cola samples in later experiments. When predicted yeast CFU values were plotted against conventional yeast CFU values for three different yeast types, a correlation coefficient of r = 0.82 was obtained.