THE RAPID DETECTION OF BREWERY CONTAMINANTS BELONGING TO THE GENUS SACCHAROMYCES—EXAMINATION OF LAGER YEASTS

For the detection of wild Saccharomyces contaminants in lager yeasts, two different sera combinations, absorbed by two different strains of Sacch. carlsbergensis, are required. The most satisfactory test system applies to lager yeasts belonging to sub-group I, where 60% of Sacch. cerevisiae contaminants are detected, all Sacch. carlsbergensis strains belonging to sub-group II, and all other brewery contaminants belonging to the genus Saccharomyces. The system used for lager yeasts belonging to sub-group II is less satisfactory: 50% of Sacch. cerevisiae strains and all Sacch. carlsbergensis strains belonging to sub-group I were detected, but only 60% of strains belonging to other Saccharomyces spp. The limitations of the antigenic structures ascribed to the various species of this genus are demonstrated, and it is suggested that an immuno-fluorescent test procedure should be used in any further studies relating to antigenic inter-relationships.