Biosynthesis of β-galactosidase from aspergillus oryzae using milk powder as substrate

The purpose of the current study was to produce highly active and stable β-galactosidase by using submerged fermentation employing indigenously isolated fungi. Different soil and food samples were collected from various waste lands and restaurants kitchens of Lahore for fungal strains isolation. X-gal based screening resulted in the isolation of 42 β galactosidase producing fungal strains. Out of these, highest production (112.34± 0.23 U/mL/min) of β-galactosidase was shown by fungal isolate IIB-26 that was further subjected to 18S rDNA sequencing and was identified as Aspergillus oryzae. This work also focused on optimizing different fermentation parameters to enhance the productivity of β-galactosidase. The maximum productivity of β-galactosidase i.e. 112.34±0.23 U/mL/min was attained using soya bean meal medium of pH 4 after 120 hours of incubation, at 30 degree C, using soya bean meal as carbon and urea as nitrogen source when it was inoculated with 3% inoculum of A. oryzae conidial suspension. The biosynthesis of enzyme was increased 3 times after optimization of fermentation parameters. The present work would help in future to decline the incidence of hypolactasia among Asian people by developing lactase supplements. (author)