Further Studies of Extracellular Enzyme Profiles of Xerophilic Fungi Isolates from Dried Medicinal Plants

摘要

The contamination of dried medicinal plants with microscopic fungi has been the subject of many studies. However, no data on extracellular enzyme activities of xerophilic fungi contaminating the plants have been found in the literature. Therefore, the objective of our study was to determine extracellular enzyme profiles of fast-growing xerophilic fungi, i.e. Aspergillus flavus, A. fumigatus, A. melleus, A. nidulans, A. niger, A. par-asiticus and Trichothecium roseum isolated from dried medicinal plants from herbal shops in Szczecin, Poland. Solid media and the API ZYM~® test were used for measuring enzyme activities. Among the fungi, A. melleus had the highest hydrolytic activity on milk, gelatin, starch, tributyrin, rapeseed oil and biodiesel oil agars, while A. fumigatus showed extremely high stimulation index values on rapeseed oil and biodiesel oil agars. The stimulation index increased during a 5-day incubation period. In the API ZYM~® test A. nidulans showed the highest hydrolase activity. Among the hydrolases, β-glucosidase activity was the highest, followed by acid phosphatase, N-acetyl-β-glucosaminidase and naphthol-AS-BI-phosphohydrolase activities. The fungi contaminating dried medicinal plants are able to utilize a number of substrates and, therefore, possess high biodeterioration potential. Due to the ability to degrade hydrocarbons, fungal isolates from dried medicinal plants can be used for biotechnological purposes, e.g. in air biofiltration and waste or soil bioremediation.