Molecular forms of lipases and their localization in the fungus Rhizopus microsporus by immuno-electron microscopy.

Several lipases differing in their molecular masses (24, 32, 43, 66 and 98 kDa and 28, 40, 45 and 69 kDa) were found in Rhizopus microsporus UzLT-4B and UzLT-5C, respectively. The lipases in each strain were immunologically related. Strain UzLT-5C grown on a medium with lipid substrate secreted lipases of 32, 66 and 98 kDa whereas strain UzLT-4B produced lipases of 45 and 69 kDa on the same medium. Immuno-electron microscopy indicated that the intracellular lipases were in peripheral zones of the hyphae, primarily in the periplasm and adjacent vesicles. Immobilization in Ca-alginate gel revealed unusual structures in the cell wall. These structures accumulated lipases and, apparently, exported the enzymes out of the cell.