First Report of Environmental Isolation of Exophiala spp. in Malaysia

The opportunistic pathogen Exophiala dermatitidis has been frequently isolated from tropical regions of the world. However, there is no report of environmental isolation of Exophiala spp. from Malaysia. The information regarding the ecology of this microbe is important for a better understanding of the opportunism. This study aims to conduct a survey of natural distribution of Exophiala spp. in Malaysia. Forty-seven strains of Exophiala-like was isolated by using selective media. These isolates from the fields were molecularly identified based on the ITS region. The biochemical activity of these microbes was tested by conducting various tests, i.e. DNase test, proteinase activity, and urea hydrolysis. Overall, 22 strains of E. dermatitidis were successfully obtained and identified from burnt tree bark, oil dripped soil sample, hot spring biofilm, railway track stones, tar road contaminated with petrol hydrocarbon, drain and deep mud of Sungai Pinang besides the new discovery from pigeon droppings. A single strain of E. heteromorpha was identified from tar road contaminated with petrol hydrocarbon. Genotypes of the isolated E. dermatitidis were identified by the neighbor-joining tree and grouped into Genotype A, A2 and B. The existence of new Genotype A4 was confirmed by a similar cladogram position in both neighbor-joining and maximum likelihood tree. The survival of E. dermatitidis in the hydrocarbon contaminated environment was studied by supplying engine oil and observing the growth pattern. The results of this study suggest that the opportunistic Exophiala spp. was isolated from nutrient limited and harsh conditions in the natural environment.