SOME PHYSICOCHEMICAL PROPERTIES OF AN EXTRACELLULAR LIPASE FROM GEOTRICHUM SP. DTQ-26.3

Abstract

In a previous study, partial sequence of26S rRNA of the yeast strain DTQ-26.3 showing the highest lipase production among 193 microbial strains isolated from soil and wastewater samples in Vietnam was determined and some culture conditions were optimized. The partial sequence of 26S rRNA indicated that the strain belonged to the genus Geotrichum, and deposited in GenBank with an accession number DQ640273 (Geotrichum sp. DTQ-26.3). To be applicable in the industry, some most important physicochemical properties of the extracellular lipase from the strain Geotrichum sp. DTQ-26.3 were determined. The extracellular lipase from Geotrichum sp. DTQ-26.3 had activity maximum at 40°C, and pH 8.0. The enzyme was stable at pH 8.0 but not thermostable. The lipase from Geotrichum sp. DTQ- 26.3 preferably hydrolyzed olive among tested commercial oils. In general, metal ions inhibited the lipase. Its activity lost from one fourth to one half, especially lipase activity lost completely with addition of 10 mM Pb2 +. Metal ion Ca2 + at the concentration of 1 mM stimulated lipase slightly, increased the lipase activity by 6%. Tested organic solvents decreased the lipase activity. Tween 20 had an effect to activate the lipase, increased the lipase activity by 11 %. The addition of 1 % of the detergent SDS inhibited lipase completely.