Rose bengal-malt extract-agar, a simple medium for the simultaneous isolation and enumeration of fungi and actinomycetes from soil.

merous than fungi, these organisms used to be suppressed by acidifying the agar medium to pH 4 to 5, but this has been made unnecessary by the addition of rose bengal to suitable media (N. R. Smith and V. T. Dawson, Soil Sci. 58:467, 1944). Counts of fungi were even higher in media containing rose bengal than in acidified media (J. P. Martin, Soil Sci. 69:215, 1960). Actinomycetes grow more slowly than do most bacteria and fungi, and hence they are likely to be masked in culture plates of ordinary media. Since the actinomycetes, as a group, are capable of growing in media containing low nitrogen, this property is used to prevent the development of the