Substrate specificities of lipases A and B from Geotrichum candidum CMICC 335426.

The mould Geotrichum candidum produces extracellular lipases with different substrate specificities according to strains. We purified two lipases - termed lipase A and lipase B - from Geotrichum candidum CMICC 335426. The specificity of the two lipases was investigated using hydrolysis assays on emulsions of pure acylglycerols and a wide range of fatty acid esters. Lipase B was very highly specific for hydrolysis of esters of cis-delta 9-fatty acids. Lipase A did not show such strict specificity, because it hydrolysed a wider variety of fatty acid esters, in particular those of palmitic acid and isomers of oleic acid. We think that differences in specificity previously observed for crude lipases from various strains of G. candidum can be explained by the presence of different levels of specific (lipase B) and non-specific (lipase A) lipases. As lipases A and B are structurally related proteins, a minor variation in structure may be responsible for the differing specificities.