In vitro conditions for budded-to-hyphal-form transition of Trichosporon asahii of different sources

Abstract

To investigate the hyphal-form transition of Trichosporon asahii (T. asahii) of different sources under different temperatures, media and cultural times; eleven T. asahii strains were isolated and maintained in RPMI-1640 medium, YPD liquid medium, Tween yeast bouillon (TYB) medium and 50% (v/v) fetal calf serum (FBS) medium independently to induce the hyphal growth. Culture was performed at 15, 25 and 37°C for 1, 2, 3, 6, 12 and 24 h and the hyphal formation (growth) rate was calculated. The mean hyphal formation rate was (0.15±0.42)% at 15, (5.75±3.48)% at 25°C and (33.81±15.39)% at 37°C (P<0.05 for all) at the same time point. The mean hyphal formation rate was (46.24±25.50)% in RPMI-1640, (36.28±21.85)% in YPD, (33.93±21.29)% in TYB and (18.60±14.58)% in 50%(v/v) FBS showing significant difference intergroups (F = 6.29, P = 0.0013) and intragroups (F = 21.80, P = 0.0000). Moreover, the mean hypha formation rate also raised in all T. asahiistrains with the prolongation of induction. Among various conditions for hypha induction ofT. asahii, culture in RBMI1640 liquid media at 37°C for 24 h is the best condition in which the hypha with high purity can be collected. The source of fungus is also an important factor influencing the hyphal growth of T. asahii. Key words: Trichosporon asahii, hyphal growth, induction, medium.