Lactase enzymes with improved properties

A peptide exhibiting increased beta-galactosidase enzyme activity in comparison to a reference peptide having the amino acid sequence of SEQ ID NO:35, wherein:

• (a) the beta-galactosidase activity is determined by conducting a lactase reaction comprising incubating 13 μl of a solution comprising a known amount of a purified lactase enzyme and 37 μl of a solution comprising 140 mM lactose at pH 6.7 and 37° C. for 10 min to obtain a reaction product comprising glucose, terminating the lactase reaction by heat, determining the amount of glucose formed by incubating the reaction product at 30° C. for 40 min with 80 μL of a solution comprising glucose oxidase (0.6 g/L) 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid diammonium salt) (1.0 g/L, ABTS) and horseradish peroxidase (0.02 g/L), and determining absorbance at 610 nm using a fluophotometer;
• (b) the increase in beta-galactosidase enzyme activity in comparison to the reference peptide,
• wherein the amino acid sequence of the peptide is selected from SEQ ID NOs. 13, 14, and 19, and amino acid sequences more than 95% identical thereto.