Chemistry Reference
In-Depth Information
5.4.1.4.1
Other Yeasts
Cryptococcus laurentii
The production of galactose transfer products by C. laurentii IFO 609 has
been examined by Onishi and Yokozeki (1992). The enzyme of this species
produces a 4
0
-galactosyl lactose from lactose. A yield of 47 g/L of 4
0
-galacto-
syl lactose was produced from 100 g/L of lactose in studies using C. laurentii
OKN-4 conducted by the Nissin Sugar Manuf. Co. Ltd., Japan (Ozawa et al.,
1991; Ohtsuka et al., 1992).
This yeast can be an opportunistic pathogen in immuno-compromised
patients. It can cause superficial infections and is described as causing funge-
mia. It has been implicated in meningitis and is regarded as a human patho-
gen. Thus, its direct use as a food-processing aid is restricted.
Sporobolomyces singularis (syn. Bullera singularis)
It has long been recognized that this basidiomycetous yeast possesses a
-hexosidaseabletobehavewithga actosidase-like activity (Gorin
et al., 1964). The nature of this action has been investigated in detail
by Ishikawa et al. (2005). It seems that the basidiomycetous yeasts
commonly possess a
-glucosidase which performs like a
-galactosidase
when presented with lactose as a substrate and is a strong producer of
galacto-oligosaccharides. Dombou et al. (1994) described a method for
the production of galacto-oligosaccharides from lactose using basidio-
mycetous yeasts. Preferred yeasts belonged to the genera of Rhodotorula,
Pichia, Sporobolomyces, Kluyveromyces, Debaryomyces, Candida, Toru-
lopsis, Cryptococcus, Trichosporon, Lipomyces and Brettanomyces.The
inventors preferred an isolate of Lipomyces starkeyi for the description
of the invention.
The purification and biochemical properties of a galacto-oligosacchar-
ide-producing
-galactosidase from B. singularis has been described by Cho
et al. (2003). Shin et al. (1995, 1998) examined optimal culture conditions for
B. singularis and continuous production of galacto-oligosaccharides in a
chitosan-immobilized system for the enzyme.
Sterigmatomyces elviae
The basidiomycete species Sterigmatomyces has been investigated for its
potential as a source of a
-galactosidase for the production of galacto-
oligosaccharides (Onishi and Tanaka, 1995; Onishi et al., 1995). The main
transgalactosylation product was a 4
0
-galactosyl lactose. In comparison with
a number of other bacteria and yeasts, the authors considered the enzyme
from S. elviae CBS 8119 to be the best galacto-oligosaccharide producer. The
