Buffered Charcoal Yeast Extract Agar (BCYE) was developed by Feeley et al.1 and then further modified by Edelstein2 for selective cultivation of Legionella species. They have very special requirements for growth. Yeast Extract provides sources of nitrogen, carbon, and vitamins in BCYE Agar. Activated Charcoal decomposes hydrogen peroxide and other toxic products. ACES Buffer was added to formulation to provide a stable pH for optimal growth. α-Ketoglutarate stimulates organism growth. Agar is the solidifying agent. L-Cysteine, in the supplement, is an essential amino acid and an important energy source for Legionella species. Ferric pyrophosphate, present in the supplement, is the iron source. For selective isolation the supplement contains selective agents like, polymyxin B, glycine, vancomycin, bromo thymol blue and bromo cresol purple. Natamycin is an inexpensive alternative to anisomycin in the formulation of selective BCYE alpha media. Macroscopic colonies of L. pneumophila were visible on the new medium within 3 days, whereas 4 days of growth was required on F-G agar.
1. Feeley, JC, RJ Gibson, GW Gorman, NC Langford, JK Rasheed, DC Mackel, WR Bane. 1979. Charcoal-yeast extract agar: primary isolation medium for Legionella pneumophila. J. Clin. Microbiol. 10(4): 437-441.
2. Edelstein, PH and MA Edelstein. 1996. Natamycin as a selective antifungal agent in media for growth of Legionella species. J. Clin. Microbiol. 34(1): 185-187.