First Report of Environmental Isolation of Exophiala spp. in Malaysia
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First Report of Environmental Isolation of Exophiala spp. in Malaysia Mehalene Jayaram1 · Hideyuki Nagao1,2 Received: 19 December 2019 / Accepted: 29 June 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract 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.
Introduction Exophiala dermatitidis is known as an opportunistic human pathogen causing fatal neurotropic agent for adolescent patients in East Asia [1–3] and for nosocomial commonsource outbreaks in USA [4, 5]. Exophiala spp. cause diseases in domestic feline [6] and marine vertebrates such as fishes, crab, and sea dragon [7–9]. On the other hand, Exophiala spp. have been commonly isolated from railway ties, faeces of frugivorous birds and bats [10], sauna facilities [11], hydrocarbon contaminated sites [12], decaying wood [13] and babassu coconut shells [14].
* Mehalene Jayaram [email protected] Hideyuki Nagao [email protected] 1
School of Biological Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia
Present Address: Agrophotonics, Merck Innovation Center, Merck Ltd., 4084 Nakatsu, Aikawa‑machi, Aiko‑gun, Kanagawa 243‑0303, Japan
2
Consistent high distribution of Exophiala spp. [10, 15] from tropical and subtropical climates has been reported besides the limited isolation from temperate regions of the world [16]. Aromatic hydrocarbons played an important role for the survival and enrichment of Exophiala fr
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