Production of Two Types of Lipases with Opposite Positional Specificity byGeotrichumsp. FO401B

Abstract

A fungus, FO401B, was isolated as a microorganism capable of assimilating sardine oil as a sole carbon source and producing a large amount of extracellular lipase; it was identified as Geotrichum sp. The fungus produced a lipase mixture that was more specific towards the 2 position, as judged by the positional specificity index, when the initial pH of a rice bran medium was raised. The lipases in the broth were purified by ion exchange and hydrophobic interaction chromatographies and termed Lipases A, B, and C. A and C gave a single band each by SDS–PAGE, but fraction B was presumed to be a mixture of Lipases A and C. A was incompletely 1,3-specific towards triolein (able to hydrolyze the 2-positioned ester at a slower rate) and, in contrast with A, C was incompletely 2-specific. The positional specificity of B was completely non specific. The optimum pHs of A and C were 7.0 and 8.5 and their molecular weights were 62,000 and 58,000, respectively.