Yeast like fungi of Malassezia pachydermatis species are numbered among the opportunistic agents accounting for acute dermatoses or even systemic infections in people and animals. They exhibit the clear heterogeneity pertaining to the phenotypic traits and growth requirements. The objective of the present study was to determine the degree of variation as well as the biochemical profiles of M. pachydermatis strains. The studies were conducted on 40 strains isolated from the auditory canal of healthy dogs and those with otitis externa symptoms recognized. An assessment was conducted of the traits of fungus morphology (size and shape of cells and colony type), expression of extracellular hydrolases (API-ZYM) and the activity of catalase, urease, caseinase, beta-glucosidase, phospholipase and Tween hydrolases: 20, 40, 60 and 80. The obtained results made it possible to determine the general metabolism pattern for this species: no fermentability or capacity for assimilation of most carbohydrates, poor proteolytic properties, high activity of enzymes from the phosphatase and lipolytic enzymes groups. On the grounds of the statistical analysis, the examined strains were classified into 7 separate groups of congenial morphology and a determined level of enzymatic activity. Biotype I includes large, smooth and creamy-white colonies of high metabolic activity; moreover, they exhibit high sensitivity to the inhibitory operation of Tween 20 and Cremophor EL; biotype II exhibits a rough type of colony growth, the lowest metabolic activity and a lack of expression of lipase C14 and enzymes from the arylamidase group; biotype III comprises the strains of large, smooth colonies, poor total enzymatic activity and with no activity of cystynic arylamidase; biotype IV includes the strains of small and smooth colonies, average metabolic activity but with optimal usability of Tween 40 and 60 hydrolysis products for growth; biotype V groups the strains of the average metabolic activity and without phospholipase activity recorded; biotype VI comprises the strains of smooth, large or medium-sized colonies and a relatively high enzymatic activity as well as the highest level for alkaline phosphatase and valine arylimidase, phospholipase, catalase, caseine, Tween 80 hydrolase; biotype VII is characterized by the highest total enzymatic activity, high capacity for eskulin break-down, Tween 40, 60 and 80 hydrolysis. Further studies are needed to demonstrate a correlation between the strain classification into a defined biotype and its ecologic or clinical status.
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