구강에서 분리한 Candida albicans의 phospholipase 활성 및 세포화학적 활성위치에 대한 전자현미경적 연구

PHOSPHOLIPASE ACTIVITY IN CANDIDA ALBICANS ISOLATED FROM ORAL CAVITY

Phospholipase have been found in many fungi and it has been suggested that they play a role in pathogenicity. In this study the author has investigated and measured the amount of phospholipase activity in Candida species and attempted a correlation between the phospholipase positive strains and the phospholipase negative strains in pathogenicity. The author also observed the cytochemical localization of phospholipase in Candida albicans. The results were as follows; 1. The identified 42 Candida species were C. albicans (36), C. parapsilosis (2),C. tropicalis (2), C. krusei (1) and C. veronae (1). 2. Among the 42 strains of Candida species, 32 (76.2%) were phospholipase positive with a mean Pz value of 0.65 ± 10.19 by plate method, whereas 35 (83.3%) were positive with a mean value of 6.09 ± 3.38 IU/L by titrimetric method. All of the phospholipase positive strains were C. albicans in plate method, whereas only one strain was not C. albicans but C. parapsilosis in titrimetric method. 3. Generally, continuous subculture of the phospholipase positive strains on Sabouraud s dextrose agar and phospholipase producing medium reduced the phospholipase activities. 4. Generally, the phospholipase activities increased in low concentration (3.0%) of egg yolk compared with high concentration (12%) of egg yolk in medium but the phospholipase activity showed most stable difference in 7%∼8% concentration of egg yolk. 5. The phospholipase positive strains had the higest phospholipase activities at pH 3.0 on medium whereas non of the strains were positive at pH 9.0. 6. The LD₅₀ (lethal dose 50) of the high phospholipase activity strains (Pz=0.37), low activity strains (Pz=0.70) and nagative strains (Pz=1.00) were 6.0 × 10⁴cells/㎖, 3.6 × 10⁵ cells/㎖, 3.7 × 10⁵ cells/㎖ in mice. The C. albicans strains which were most pathogenic in mice had the highest phospholipase activity. 7. In the electron microscopic findings, the phospholipase in C. albicans were localized at the cell membrane and cell wall. Most of the phospholipase activity appeared to originate in the cell membrane.