Hydrolysis of lactose by immobilized microorganisms

Abstract

Cells ofLactobacillus bulgaricus, Escherichia coli, and Kluyveromyces (Saccharomyces) lactis immobilized in polyacrylamide gel beads retained 27 to 61% of the /3-galactosidase activity of intact cells. Optimum temperature and pH and thermostability of these microbial f3-galactosidases were negligibly affected by the immobilization. K, values of /3-galactosidase in immobilized cells of L. bulgaricus, E. coli, and K. lactis toward lactose were 4.2, 5.4, and 30 mM, respectively. Neither inhibition nor activation of /3-galactosidase in immobilized L. bulgaricus and E. coli appeared in the presence of galactose, but remarkable inhibition by galactose was detected in the case of the enzyme of immobilized K. lactis. Glucose inhibited noncompetitively the activity of three species of immobilized microbial cells. These kinetic properties were almost the same as those of free /8-galactosidase extracted from individual microorganisms. The activity of immobilized K. lactis was fairly stable during repeated runs, but those ofE. coli and L. bulgaricus decreased gradually. These immobilized microbial cells, when introduced into skim milk, demonstrated high activity for converting lactose to monosaccharides. The flavor of skim milk was hardly affected by treatment with these immobilized cells, although the degree of sweetness was raised considerably.

Formation of Oligosaccharides During Hydrolysis of Lactose in Milk Using β‐Galactosidase from Bacillus circulans

“…However, in the case of treatment of milk with P-galactosidase, only a few investigators (Ohmiya et nl., 1977;Burvall et al, 1979;Greenberg and Mahoney, 1983) examined the oligosaccharide production. Ohmiya et al (1977) showed qualitatively that fewer oligosaccharides were produced during hydrolysis of lactose in milk using immobilized cells of L.…”

“…1979;Greenberg and Mahoney, 1983). Ohmiya et al (1977) studied oligosaccharides production during hydrolysis of lactose in skim milk with immobilized cells of Lnctobncillus bul~aricus, Escherichio coli, and Kluyveromyces lactis. Burvall et al (1979) studied the formation of ohgosaccharides during hydrolysis of 5% lactose in milk with K. /actis P-galactosidase and found 5% oligosaccharide at its maximum.…”

Immobilization of <i>Lactobacillus plantarum</i> B134 Cells using Sodium Alginate for Lactose Hydrolysis in UHT Milk

“…In the present study, the immobilization effeciency of L. plantarum B134 cell was 28.95% based on assayable β-galactosidase activity. Ohmiya et al (1977) reported that an immobilization efficiency of Kluyveromyces lactis cells were 4.2 mM, 5.4 mM, and 30 mM, respectively (Ohmiya et al 1977). Banerjee et al (1982) reported that K M value of β-galactosidase in immobilized-and free Saccharomyces anamensis cells were 148 mM and 102 mM, respectively.…”

Enzymes other than rennets in dairy technology

“…Production, purification and immobilization Kilara, Shahani & Wagner (1977), Pitcher, Ford & Weetall (1976) and Ohmiya et al (1977) examined the preparation and characterization of immobilized ,a-galactosidase systems; the latter group immobilized whole microbial cells in polyacrylamide gels. Stanley et al (1975), Liu et al (1975), Ngo, Narinesingh & Laidler (1976 and Brandt, Wang & Leeder (1976) immobilized ,a-galactosidase on chitin, carbon, nylon and collagen respectively.…”