Screening and characterization of β-galactosidase activity in lactic acid bacteria for the valorization of acid whey

Graphical Abstract Summary: Bioinformatic analysis as the first screening of β-galactosidase activity of multiple species and strains of LAB provides valuable information for selecting strains with this activity. Following inoculation in acid whey (AW) and commercial medium (de Man, Rogosa, and Sharpe; MRS), kinetic growth parameters were determined. To find strains with high β-galactosidase activity, different substrates were used (o-nitrophenyl-β-d-galactopyranoside and β-d-galactopyranoside). LAB showed higher β-galactosidase activity when cultured in AW compared with commercial MRS medium; thus, AW secondary metabolites likely complement the upregulation to promote enzyme production. Lactobacillus helveticus OSU-PECh-4A was identified as a strain with exceptional β-galactosidase activity. The bgal-620 gene was upregulated in OSU-PECh-4A cultured in AW. This strain can valorize AW and be used to further study β-galactosidase.