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A total of 278 different isolates of filamentous fungi were screened using synthetic medium for respective ability to produce kojic acid. Nineteen, six, and five isolates proved to be low, moderate, and high kojic acid producers, respectively. Levels of kojic acid produced were generally increased when shaking cultivation was used rather than those obtained using static cultivation. A trial for the utilization of 15 agro-industrial wastes or by-products for kojic acid production by the five selected higher kojic acid producer isolates was made. The best by-product medium recorded was molasses for kojic acid. A. flavus numbers 7 and 24 were able to grow and produce kojic acid on only 12 out of 15 wastes or by-products media. The best medium used for kojic acid production by A. flavus number 7 was rice fragments followed by molasses, while the best medium used for kojic acid production by A. flavus number 24 was the molasses followed by orange, pea, and rice fragments. An attempt for production of kojic acid using a 1.5 L laboratory fermentor has been made. Aspergillus flavus number 7 was used and grown on molasses medium; maximum level (53.5 g/L) of kojic acid was obtained after eight days of incubation.

Fifty-five species and two varieties appertaing to 23 genera were collected and identified from 4 samples of dried fig and 3 dried samples of each of apricot, plum and raisin. Forty-nine species and two varieties belonging to 20 genera were isolated on 1% glucose-Czapek's while 31 species and one variety belonging to 16 genera were isolated on 40% sucrose-Czapek's agar medium at 28 +/- 2 degrees C. Penicillium, Aspergillus and cladosporium were the common genera on the two types of media used. Alternaria and Pleospora were common on 1% glucose-Czapek's agar only while the genus of Eurotium was isolated with high occurrence on 40% sucrose-Czapek's agar. The common species on the two types of media used were Penicillium chrysogenum, Aspergillus niger and cladosporium cladosporioides. On 1% glucose-Czapek's agar, P. aurantiogriseum, A. fumigatus, A. flavus, Alternaria tenuissima and Pleospora herbarum were isolated with high occurrence while A. versicolor, A. wentii, Eurotium amstelodami and E. chevalieri were common on 40% sucrose-Czapek's agar. The different dried fruit samples were assayed for the natural occurrence of aflatoxins B1, B2, G1 & G2, citrinin, ochratoxins, patulin, sterigmatocystin, diacetoxyscirpenol, T-2 toxin and zearalenone by thin layer chromatographic analysis. Ochratoxin A was detected in all samples tested of apricot (50-110 micrograms/kg), fig (60-120 micrograms/kg) and plum (210-280 micrograms/kg). The other mycotoxins under investigation were not detected. All samples examined of raisin proved to be mycotoxin free.

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