HYDROLASE ACTIVITY OF 150 MALASSEZIA-FURFUR ISOLATES OF DIFFERENT CLINICAL-ORIGIN

Apart from pityriasis versicolor, Malassezia furfur is thought to play a significant role in the pathogenesis of seborrhoic eczema and Malas sezia folliculitis. However, it has not been clarified whether in addi tion to host factors (e.g. immune status, greasy skin), yeast-dependen t activities are responsible for manifestation of the disease. In this context interstrain variability of hydrolase activity of Malassezia i solates might be significant. For determination of hydrolase activity, washed yeast suspension was applied to selective agar for pathogenic fungi containing 8% (v/v) Tween 80 or Tween 60 and was incubated at 37 degrees C for 10 days. Growth was accompanied by formation of a dense white zone around the colony, in which free fatty acids corresponding to Tween 80 (C18:1) or Tween 60 (16:0, 18:0) were demonstrated by mea ns of thin layer and gas chromatography. Thus, this phenomenon is a pa rameter for yeast-dependent hydrolysis of Tween 80 and Tween 60. Consi dering different growth behaviour, a 'hydrolase zone' (H-z) was determ ined using the quotient colony diameter/(ring + colony) diameter in ea ch of the 150 strains tested. Although no significant H-z variations w ere observed in strains of different clinical origin, the present stud y revealed that in addition to a known enzyme, which is located within the cell wall and/or membrane systems, these Malassezia isolates prod uce a very active hydrolase diffusing into the medium.