ISOLATION OF YEASTS FROM SOIL WITH THE AID OF ACID, ROSE BENGAL, AND OXGALL

Abstract

Yeasts were isolated by the dilution plate method from 9 of 10 soils. Results indicated an average of 1000 per g. and a max. approximately 50,000. When incorporated in potato dextrose agar, three antibacterial agents, lactic acid (pH 4), rose bengal (0.003%), and oxgall (1%) facilitated detection and isolation of soil yeasts. Rose bengal and oxgall were more useful in this regard because they also restricted growth of spreading fungi. Their restrictive effect on fungus growth was conditioned by the nature of the plating medium. Both gave satisfactory results with all 10 soils when used in potato dextrose agar.