The mycobiota of herbal drug plants in Oman and possible decontamination by gamma radiation

The mycobiota of seven herbal plant species were surveyed: Nigella sativa, Zataria multiflora, Trigonella foenum-graecum, Rhazya stricta (seeds and leaves), Haplophyllum tuberculatum, Aristolochia bracteolata and Teucrium muscatense. A total of 24 species of fungi were isolated from the plants (seeds, leaves, flowers and/or stems). No significant differences were found between the mycobiota of the herbal plant species or between the six samples of each plant. Aspergillus niger and Penicillium sp. were the most common species, followed by A. flavus and Rhizopus spp. A. flavus was found in all herbal plants except R. stricta (leaves) and Z. multiflora. Aflatoxins were extracted from a number of herbal plants. Some strains of A. flavus isolated from the plants were aflatoxigenic. Gamma radiation at 905.4 Gy showed an average percent inhibition of fungi on some herbal plants between 88.6 and 99.1%. Complete inhibition was obtained at 1836 Gy.