The formation of germ tubes byCandida albicansin various peptone media

Seventy-nine isolates of Candida albicans and 33 of 5 other pathogenic species of Candida were cultured for 3 h at 37°C in 1·5% aqueous solution of 6 peptone media. While all isolates of C. albicans formed germ tubes, the other species did not. Some isolates of C. albicans formed germ tubes in 1·5% trypticase peptone and neopeptone, and all did so in phytone, bactopetone, polypeptone and proteose peptone at the same concentration. Subsequently, 140 isolates of C. albicans were inoculated at the rate of 106 organisms/ml into concentrations of bactopeptone from 0·5% to 2·5%, into distilled water and into undiluted sheep serum. The tendency to germ tube formation was greater in 1% than in 0·5% bactopeptone, and in both of these media it was greater than in other concentrations of bactopeptone or whole sheep serum. Germ tube formation also occurred to a very limited extent in distilled water. The significance of these findings is discussed.