De. Stevenson et al., OLIGOSACCHARIDE AND ALKYL BETA-GALACTOPYRANOSIDE SYNTHESIS FROM LACTOSE WITH CALDOCELLUM-SACCHAROLYTICUM BETA-GLYCOSIDASE, Enzyme and microbial technology, 18(8), 1996, pp. 544-549
The synthetic utility of the thermostable beta-glycosidase from Caldoc
ellum saccharolyticum was investigated. The ability of the enzyme to c
atalyze oligosaccharide and beta-galactopyranoside synthesis from lact
ose was compared with that of the readily commercially available, mode
rately thermostable beta-galactosidase (beta-D-galactoside galactohydr
olase, EC 3.2.1,23) from Aspergillus oryzae. Generally the C. saccharo
lyticum enzyme showed significantly greater resistance to inactivation
by heat and organic solvent and better yields of product. Although th
e A. oryzae enzyme gave better oligosaccharide yields at lower lactose
concentrations, at higher concentrations (above 50% w/w) the C. sacch
arolyticum enzyme was significantly better, yielding a sugar mixture c
ontaining 42% by weight of tri- plus tetra-saccharides, from a 70% w/w
lactose solution, compared with 31% by weight of oligosaccharides wit
h the A. oryzae enzyme. In ethyl galactoside synthesis from ethanol an
d lactose, neither enzyme appeared to hydrolyze the product to any gre
at extent. Under all conditions rested, the product yield did not peak
, even at long reaction times, when most of the lacro;ze had been cons
umed. The C. saccharolyticum enzyme, however, gave slightly higher pro
duct yields and could be used at higher ethanol concentrations without
serious loss of activity.