Yoshiaki Yagi

Isolation and characterization of branched cyclodextrins

Abstract Three branched cyclodextrins (CDs) were isolated by high-performance liquid chromatography (l.c.) from the mother liquors of a large-scale preparation of the unbranched CDs with Bacillus ohbensis cyclomaltodextrin glucanotransferase. Evidence from chromatographic behavior on three l.c. columns of different separation modes, fragmentation analysis, 13C-n.m.r. spectroscopy, methylation analysis, and fast-atom bombardment-mass spectrometry (f.a.b.—m.s.) indicated that these compounds were 6-O-α- d -glucopyranosylcyclomaltohexaose (1), 6-O-α- d -glucopyranosylcyclomaltohepataose (2), and 6,6‴-di-O-α- d -glucopyranosylcyclomaltoheptaose (3).

Production of levan by a Zymomonas sp.

Abstract An ethanol-producing bacterium, IN-17-10, was isolated from palm sap. The broth was highly viscous when the strain was cultivated in a medium containing sucrose. The viscous substance was identified as a levan by analyses with HPLC and 13 C-NMR. The bacterium IN-17-10 was identified taxonomically and via a DNA/DNA homology test as a strain of Zymomonas mobilis subsp. mobilis . This strain produced levan from sucrose in a high yield (53% of the theoretical maximum) when cultivated in a medium containing 15% sucrose.

Synthesis of novel sugars, oligoglucosyl-inositols, and their growth stimulating effect forBifidobacterium

SummaryNovel sugars, oligoglucosyl-inositols, which were synthesized using CGTase fromBacillusohbensis, stimulated the growth ofBifidobacterium. The enzyme catalyzed transglucosylation from α-1,4-maltodextrin (donor) tomyo-inositol (acceptor). Of donors examined, β-cyclodextrin gave superior oligoglucosyl-inositol yield of 56.6% (w/w) based on the conversion ratio of incubated inositol. Maltosyl-inositol stimulated growth ofB.adolescentis by 194% when compared with glucose.

Synthesis of glucosyl-inositol using a CGTase, isolation and characterization of the positional isomers, and assimilation profiles for intestinal bacteria

A novel disaccharide, glucosyl-inositol, was obtained by glucoamylase digestion of the oligoglucosylinositols synthesized frommyo-inositol as an acceptor and β-cyclodextrin as a donor by transglucosylation of CGT ase fromBacillus ohbensis. The glucosyl-inositol fraction was separated by ion-exchange column chromatography and two positional isomers contained in the fraction were isolated by crystallization and HPLC on a graphitized carbon column. The structure of one of the two isomers isolated was fully determined as 1L(D)-5-O-α-D-glucopyranosyl-myo-inositol and another one was presumed as 1D-4-O-α-D-glucopyranosyl-myo-inositol from physicochemical data, H-H and C-H COSY NMR analyses and FAB-MS spectra. The disaccharide was assimilated byBifidobacterium adolescentis, B. breve, B. infantis andB. longum. On the other hand, it was not utilized byE. coli, Clostridium butyricum, C. clostridiiforme andKlebsiella pneumoniae.

Selective degradation of β- and γ-cyclodextrin by co-digestion using a CGTase fromBacillus ohbensis and α-glucosidase for efficient α-cyclodextrin recovery

A simple and specific recovery method for α-cyclodextrin (α-CD) was developed by employing co-digestion of CD reaction mixtures with CGTase fromBacillus ohbensis and α-glucosidase. The combination of CGTase fromB. ohbensis and α-glucosidase, such as α-amylase, β-amylase, or glucoamylase was examined for the selective degradation of β-and γ-CD in the CD reaction mixture formed by CGTase fromB. macerans. The co-digestion of the CD mixture with Taka-amylase and the CGTase resulted in α-CD and maltodextrins, the combination with β-amylase resulted in α-CD and maltose, and that with glucoamylase resulted in α-CD and glucose. The conditions of selective degradation of β- and γ-CD by co-digestion with the CGTase and glucoamylase were optimized as follows: the incubation pH, 5.5; incubation temperature, 50°C; CGTase concentration, 15 u/g of substrate; glucoamylase, 10 u/g of substrate; substrate concentration, 10% (w/v); the incubation time was fixed for 18 hr from the stand point of operation convenience.

Genetic Recombination by Spheroplast Fusion of Zymomonas Auxotrophs

Abstract Auxotrophic mutants were isolated from Zymomonas mobilis NRRL B-14023 by NTG treatment. Eleven out of 18 auxotrophs that turned into spheroplasts in a culture medium containing glycine and/or penicillin could be regenerated into intact cells with the order of 1–10% in frequency. By using auxotrophy as selective markers, prototrophic fusants were obtained with a frequency of the order of 10 −6 per number of progeny regenerated. The fusants obtained were confirmed from the segregation test to be genetic recombinants.