Production of extracellular α-galactosidase by mesophilic filamentous fungi during submerged cultivation

Mesophilic filamentous fungi of genera Aspergillus, Penicillium, Trichoderma and Humicola were tested for a-galactosidase production in submerged shake cultures using a soy meal extract as nutrient medium. The strains grew well in pellet forms and/or filamentous mycelia during 120 h of cultivation and extracellular alpha-galactosidase activity was registered. The strain Humicola lutea 120-5 manifesting significant activity (similar to 500 units/l) was further cultivated in laboratory bioreactor. A maximal yield of alpha-galactosidase activity (similar to 1500 units/l) was reached at the 144th h when the hyphae lysis was observed by microscopic studies. The lyophilized enzyme preparation of a-galactosidase stored at 4 degrees C maintained its activity for at least one year.