SCREENING OF YEAST AND FUNGAL STRAINS FOR LIPOLYTIC POTENTIAL AND DETERMINATION OF SOME BIOCHEMICAL-PROPERTIES OF MICROBIAL LIPASES

For the screening of yeast and fungal strains with lipolytic potential from Chem. Pharm. Res. Institute Culture Collection, we employed a se nsitive agar plate method, using a suitable medium supplemented with C aCl2 and Tween 80. By determination of the opacity areas developed aro und the colonies of lipolytic microorganisms consisting of calcium soa ps, the good lipase producing strains were selected. Candida lipolytic a CPhI-50 and Hansenula anomala CPhI-23 from the yeast strains and Rhi zopus nigricans CPhI-Rn-8, Aspergillus oryzae CPhI-20-9 and Aspergillu s niger CPhI-8-N-9 from the fungal strains were good lipase producers. When these strains were submerged cultivated on modified GYP medium, Candida lipolytica CPhI-50 and Aspergillus oryzae CPhI-20-9 had the hi ghest yield of lipase in the medium at the end of the bioprocess. Also , we determined the pH dependence of lipase activities from the good p roducing strains, and we found that these enzymes exhibited various pH sensitivities, dividing them into three groups. I. lipase active at p H 5.0-6.5 produced by Candida lipolytica CPhI-50. II. lipase active at pH 6.5-7.5 produced by Hansenula anomala CPhI-23 and Rhizopus nigrica ns CPhI-Rn-8. III. lipase active at pH 7.5-8.5 produced by Aspergillus oryzae CPhI-20-9 and Aspergillus niger CPhI-8-N-9. By screening at 50 degrees C and pH 8.5 we identified a thermostable semialkali-tolerant lipase produced by Aspergillus niger CPhI-8-N-9.