9^th Biotechnology Congress

Biography

Biography: Sulaiman A. Alrumman

Abstract

Protease enzymes have been found to be very important for the industry due to their applications in the different fields. In this study, 23 yeast isolates were showed protease activity using casein hydrolysis test. Out of the 23 proteolytic yeast isolates, 5 isolates (21.74%) designated as KKU-M 12c, KKU-M 13c, KKU-M 18c, KKU-M 19c, and KKU-M20c were identified as protease producers by exhibited high zones of clearance around the colonies. The selected five yeast isolates were identified by sequencing D1/D2 of 26S rDNA region and phylogenetic analysis as KKU-M12c Rhodotorula mucilaginosa , KKU-M13 Cryptococcus albidus , KKU-M18 Pichia membranifaciens , KKU-M19c Hanseniaspora uvarum and KKU- M20c Candida californica. To detect the optimum pH for the yeast extracellular proteases production, the influence of varying pH ranges (4.0–9.0) on the yield and activity of the proteases enzymes was investigated with 0.5% (w/v) casein as substrate. The enzyme activity was measured using qualitative and quantitative assays. Results showed that all the yeast under study secreted protease enzyme at varied levels of pH except pH 9.0 indicating that the five studied yeasts are not alkaline protease producers. The maximum activity of protease (187 U/ml) was observed by strain H. uvarum KKU-M19 at only pH 6.0 . The result indicated that this yeast (KKU-M19) produced only neutral protease enzyme. The results of pH studies also showed that the other four yeast isolates R. mucilaginosa KKU-M12, C. albidus KKU-M13, P. membranifaciens KKU-M18 and C. californica KKU-M20 were produced both acidic (at pH 4.0) and neutral (at pH 6.0 and 7.0) protease enzymes. The C. californica strain KKU-M20c was found to be the best acidic and neutral protease producer (138 U/ml at pH4 and 185 U/ml at pH7 respectively).