P129: Production of antifungal agents from tropical strains of Aureobasidium pullulans

Production of antifungal agents from 10 tropical strains of Aureobasidium pullulans including Deenarn001BCU, Deenarn003BCU, Deenarn008BCU, Deenarn007BCU, Deenarn009BCU, NRRL58514, NRRL58536, NRRL58516, NRRL58517 and NRRL58520 was investigated.  All strains were cultivated for antifungal agent production and the extracts were tested for antifungal activity against 4 pathogenic Aspergillus spp. (A. flavus, A. niger, A. fumigatus, A. terreus) using well-diffusion method and conidial germination inhibition assay.  The extract from A. pullulans NRRL58536 showed the most efficient inhibitory activities against all 4 Aspergilli.  This strain was selected to enhance antifungal agent production using carbon source optimization including glucose and sucrose at the concentrations of 1.5, 2.0 and 2.5% (w/v).  The percent inhibition of the extract was calculated in comparison with that of 0.1 mg/ml amphoteracin B. The most effective extract was obtained from the fungus grown in 2.5% (w/v) of glucose by exhibiting inhibitory activity at 75, 60, 60 and 50% for A. flavus, A. niger, A. fumigatus and A. terreus, respectively. When adding amino acids (0.01% w/v each) into production medium as nutrient supplement,  the highest antifungal activities against A. flavus was obtained from the crude extract of A. pullulans NRRL 58536 grown on the medium containing Phenylalanine and Leucine with percent inhibition of 175% while the medium containing  Proline and Leucine gave the highest antifungal activities against A. terreus with percent inhibition of 120%.  The medium containing Phenylalanine together with Proline and Leucine gave the highest antifungal activity against A. niger and A. fumigatus with percent inhibition of 146 and 170% respectively.