초록
<P><B>Abstract</B></P> <P>Whey powder, a by-product of dairy industry, is an attractive raw material for value-added products. In this study, utilization of whey powder as substrate for low-cost preparation of β-galactosidase as main product and ethanol as by-product were investigated by a litre-scale integrated strategy, encompassing fermentation, isolation, permeabilization and spray drying. Firstly, through development of low-cost industrial culture and fed-batch strategies by <I>Kluyveromyces lactis</I>, 119.30U/mL β-galactosidase activity and 16.96mg/mL by-product ethanol were achieved. Afterward, an up-dated mathematic model for the recycling permeabilization was established successfully and 30.4g cells sediment isolated from 5L fermentation broth were permeabilized completely by distilled ethanol from broth supernatant. Then β-galactosidase product with 5.15U/mg from protection of gum acacia by spray drying was obtained. Furthermore, by-product ethanol with 31.08% (v/v) was achieved after permeabilization. Therefore, the integrated strategy using whey powder as substrate is a feasible candidate for industrial-scale implementation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Whey powder was used for high-production of β-galactosidase by an integrated process. </LI> <LI> The integrated process was developed successfully in a litre scale. </LI> <LI> An up-dated mathematic model for the recycling permeabilization was established. </LI> <LI> β-Galactosidase product was 5.15U/mg and by-product ethanol was 31.08% (v/v). </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>