Kozo Hara

Isolation and cultivation of a novel microorganism producing a maltopentaose-forming enzyme

SummaryA novel microorganism producing a maltopentaose-forming enzyme was screened from a soil sample. The enzyme produced by the bacteria formed maltopentaose from starch during the first stage of the reaction. The bacterium was characterized asPseudomonas sp. (KO-8940) on the basis of its morphological, physiological and biological properties. Culture conditions for enzyme production were investigated and established. The medium was composed of beef extract 0.8%, ammonium sulphate 1.0% and maltose 0.8% in tap water. Optimum conditions for bacterial growth were: initial pH 8.0, temperature 45°C, and 3 days cultivation with a rotary shaker (200 rpm). The broth supernatant obtained contained the maltopentaose-forming crude enzyme, with which 40% of starch was converted to maltopentaose.

Analyses of a Mixture of Glucosyl-Cyclomaltoheptaoses Prepared on an Industrial Scale

ABSTRACT A mixture of glucosyl-cyclomaltoheptaoses (β-cyclodextrins, βCDs) was prepared by glucoamylolysis of a mixture of maltosyl-βCDs which was produced on an industrial scale from maltose and β CD through the reverse action of Klebsiella pneumoniae pullulanase. Glucosyl-βCDs in the mixture were separated by HPLC on a reversed phase column and their molecular weights were measured by FAB-MS. In addition, the number of side-chains in each molecule was confirmed by methylation analysis and it was proved that the mixture comprised mainly of a monoglucosyl-βCD [G-β CD] and diglucosyl-β-CDs [(G)2-βCDs], and as a minor component triglucosyl-β CDs [(G)3-βCDs], and that G-, (G)2-, and (G)3-β CDs were produced in the ratios of 50%:45%:5%. The structures of three positional isomers of (G)2-β CD were established by HPLC analysis of partial hydrolyzates, 13C NMR spectroscopy, and chemical synthesis. Four regioisomeric (G)3-β CDs which could be isolated were characterized by 13C NMR spectroscopy.

The structure of high molecular weight dextrins obtained from potato starch by treatment with Bacillus macerans enzyme

Abstract Bacillus macerans enzyme (BME)-derived high molecular weight dextrins, which are by-products in the course of the industrial production of cylodextrins, were isolated and their chemical structures were characterized. Dextrin I was obtained in a yield of about 24% from BME-hydrolyzate (a mixture of dextrin and cylodextrins, 50% each) of potato starch by fractionation with an ultrafiltrator having a membrane of cut-off molecular weight 2.0 × 104. Dextrin II was obtained in a yield of about 15% from BME-hydrolyzate (a mixture of dextrins and cyclodextrins, 70 : 30) of Dextrin I by the same method. Dextrin I and II consisted of dextrin having molecular weights over 20 × 106 and dextrins having molecular weights 4 × 103−1 × 105 in the ratio of 80 : 12 and 66: 15, respectively. The results of hydrolysis by β-amylase and methylation analysis indicated that the average, exterior and interior chain lenghts of the dextrins having molecular weights over 20 × 106 and 4 × 103−1 × 105 from Dextrin I were 16.5, 8.2 and 7.3, and 11.5, 6.9 and 3.6, respectively, than those from Dextrin II were 13.6, 4.7 and 9.9, and 10.4, 5.1 and 4.3, respectively.

Chemical characterization of dextrins obtained from potato starch by treatment with Bacillus macerans enzyme

Abstract Potato starch was degraded with Bacillus macerans enzyme (BME), and the degradation product (a mixture of dextrins and cyclodextrins, 56.4:43.6) was separated by gel chromatography on Bio-Gel P-10 and Sepharose CL-2B into four fractions, I-1 (mol wt > 20 × 106), I-2 (mol wt 2 × 104-1 × 105), II (mol wt 1.5 × 103-2 × 104) and III (mol wt

Protection of Bioreactor from Bacterial Contamination by the Introduction of High Concentration of Dissolved Oxygen

The protection of a cyclomaltodextrin glucanotransferase (CGTase) bioreactor from bacterial contamination by the introduction of a high concentration of dissolved oxygen was investigated. The concentration of dissolved oxygen (DO) in the substrate (4% branched dextrin) was 80-90 ppm under a pressure of 2.5-2.8 kg/cm2 at 50°C. The continuous operation of the bioreactor for about one month gave a good result. More specifically, the introduction of a high concen-tration of DO in the substrate could control the bacterial count therein under 4 x 103 /ml. On the other hand, the activity of immobilized CGTase was not affected by high DO concentration. The bioreactor could attain a branched cyclodextrins production yield as high as 10% (w/w) for one month.