Media selectivity may be enhanced through acidification or through addition of selective agents. YM Agar should be sterilized without pH adjustment and sterile acid added to the sterile molten medium cooled to 45–50°C. Acidified YM Agar should not be heated. Antibiotics may be aseptically added to the sterile media. Other fungistatic materials, such as sodium propionate and diphenyl may be added to YM Agar to eliminate molds and permit the enumeration of yeasts in mixed populations.
Good cultural response at pH 6.2 (4.1% solution, 25°C): Aspergillus brasiliensis (niger) 16404, Candida albicans 10231, Escherichia coli 25922, Lactobacillus rhamnosus 7469, Saccharomyces cerevisiae 9763
Yeast extract is a source of trace elements, vitamins and amino acids
Malt extract is a source of carbon, protein and nutrients
Peptone is an additional source of carbon and provides nitrogen and amino acids
Dextrose provides carbon
Agar is the solidifying agent
Specifications
Beige
<30°C
Cultivation of yeasts, molds and other aciduric microorganisms