Soy Meal Waste Extract as Cultivation Medium for Production of Extracellular α-Galactosidase from the Fungus Humicola Lutea 120–5

Abstract

ABSTRACTSoy meal extract presenting a waste product from soy protein concentrate manufacture was applied as cultivation medium for the production of extracellular α-galactosidase in submerged fermentation of the filamentous fungus Humicola lutea 120–5. Maximum enzyme activity (2000 U.l−1) was produced when the soy meal extract containing 5% dry substances (∼1% raffinose oligosaccharides) was used at 120th h cultivation and 35°C. Chromatography on Sephadex G-100 and DEAE-cellulose resulted in a purified α-galactosidase fraction with specific enzyme activity of 37 U.mg−1. The optimum conditions for the enzyme reaction were pH 4.0 to 4.5 at 50°C. The partially purified enzyme was stable up to 40°C at pH 2.0 to 7.5. The crude enzyme preparation readily hydrolyzes raffinose according HPLC analysis, but no activity against disaccharides as sucrose and melibiose was observed. The soy meal waste extract can be recommended as a suitable medium for the industrial cultivation of strains producing α-galactosidase for food and fodder purposes.