ASLA Agar Base is recommended for selective isolation and cultivation of Propionibacterium species from food. This medium is recommended by APHA for the isolation of Propionibacteria from cheese. The individual colonies may be confirmed as Propionibacteria by microscopic examination for typical pleomorphic rod shape and by detection of propionic acid production by gas chromatography or HPLC. This medium may not support the growth of all Propionibacteria present in natural sources.