Donal F. Day

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Leuconostoc mesenteroides B-512 FMC produces dextran and levan using sucrose. Because of the industrial importance of dextrans and oligosaccharides synthesized by dextransucrase (one of glycansucrases from L. mesenteroides), much is known about the dextransucrase, including expression and regulation of gene. However, no detailed report about levansucrase,(More)
There is an emerging market for functional oligosaccharides for use in foods. Currently, technology for the production of oligosaccharides is limited to extraction from plant sources, acid or enzymatic hydrolysis of polysaccharides or synthesis by transglycosylation reactions. Oligosaccharides can also be produced using a Leuconostoc fermentation and(More)
A beta-glucosidase (EC from the fungus Aspergillus terreus was purified to homogeneity as indicated by disc acrylamide gel electrophoresis. Optimal activity was observed at pH 4.8 and 50 degrees C. The beta-glucosidase had K(m) values of 0.78 and 0.40 mM for p-nitrophenyl-beta-d-glucopyranoside and cellobiose, respectively. Glucose was a(More)
In this study, three epigallocatechin gallate glycosides were synthesized by the acceptor reaction of a glucansucrase produced by Leuconostoc mesenteroides B-1299CB with epigallocatechin gallate (EGCG) and sucrose. Each of these glycosides was then purified, and the structures were assigned as follows: epigallocatechin gallate 7-O-alpha-D-glucopyranoside(More)
A novel glucanhydrolase from a mutant of Lipomyces starkeyi ATCC 74054 was purified. The single protein (100 kDa) showed either dextranolytic or amylolytic activity. We referred to the glucanhydrolase as a DXAMase. The DXAMase was produced in a starch medium and it was 3.75-fold more active for hydrolysis of the purified insoluble-glucan of Streptococcus(More)
A derepressed and partially constitutive mutant for dextranase of Lipomyces starkeyi was selected after ethyl methane sulphonate mutagenesis by zone clearance on blue dextran agar plates. The mutant produced dextranase when grown on glucose, fructose and sucrose as well as on dextran, and more enzyme was produced by the mutant than by the parental strain(More)
The beta-fructofuranosidase from Kluyveromyces fragilis was purified to one band on electrophoresis by 3 different methods. Two of the preparations were found to be impure by isoelectric focusing. This demonstrates the need for more than one criteria of homogeneity when purifying this enzyme. The enzyme was found to be a glycoprotein, stable at 50 degrees(More)
The optimal growth rate ofLipomyces starkeyi, with dextran as sole carbon source, was found within the pH range 2.5–4.0, and temperature between 25–30°C. This yeast was unable to grow above 33°C. Dextranase production optima paralleled growth optima, except at pH 2.5. Decrease in enzyme yield at this pH could not be attributed to poor yeast growth or enzyme(More)
Bioconversion of (4R)-(+)-limonene to (4R)-(+)-α-terpineol by immobilized fungal mycelia of Penicillium digitatum was investigated in batch, repeated-batch and continuously fed systems. The fungi were immobilized in calcium alginate beads. These beads remained active for at least 14 days when they were stored at 4 °C. Three different aeration rates were(More)
The mixture of polysaccharides in the gelling component of agar (agarose) is hydrolyzed to D-galactose and 3,6-anhydro-L-galactose by a series of hydrolytic enzymes obtained from Pseudomonas atlantica. The final degradative step in the pathway of agarose decomposition is the hydrolysis of the alpha-linkage in the dissaccharide neoagarobiose yielding(More)