Yojiro Koba

Preparation of Koji from corn hulls for alcoholic fermentation without cooking

Abstract Corn hulls, the outer peel covering the corn grain, were used for preparation of koji , which was applied to alcoholic fermentation without cooking of raw strachy materials. Corn hull koji had lower saccharifying power, α-amylase, CMCase and xylanase than wheat bran koji , but higher protease and pectinase activities, Its alcoholic fermentations of cassava starch and sweet potato were also superior to those of wheat bran koji : corn hull koji gave 10.3% (v/v) of alcohol with 93% yield from 20 g of cassava starch, while wheat bran koji gave 9.4% (v/v) of alcohol with 90.4% yeild; and corn hull koji gave 9.1% (v/v) of alcohol with 92.6% yielded from 50 g of sweet potato, while wheatbran koji gave 8.1 (v/v) of alcohol with 88.6% yield.

Action of amylase inhibitors produced by Strepromyces sp. On some carbohydrate hydrolases and phosphorylases

Abstract The amylase inhibitor produced by Streptomyces sp. has been separated into four fractions (inhibitors A, B, B′, and C) that were homogeneous by paper chromatography and paper electrophoresis. These inhibitors acted not only on glucoamylase and alpha amylase, but also on α- d -glucosidase, cycloamylose glucanotransferase, and phosphorylase. The amylase inhibitors A and B slightly activated yeast α- d -glucosidase.

Characterization of newly isolated Bacillus subtilis C1 which is sensitive to antibiotic produced by lactic acid coccus

Abstract An aerobic, Gram-positive endospore-forming rod, strain C1, was isolated from a contaminated culture of Lactococcus lactis IO-1. Strain C1 was more sensitive to nisin and the peptide antibiotic produced by strain IO-1 than Bacillus subtilis JCM 1465 T . Strain C1 was significantly different from B. subtilis JCM 1465 T in that it produced a black pigment. Conventional identification techniques did not give enough information to determine the taxonomic position of strain C1. DNA-DNA hybridization revealed that the homology value between strain C1 and JCM 1465 T was as high as 94% under optimal conditions. Thus, strain C1 was identified as a strain of B. subtilis . It was demonstrated that strain C1 was an effective indicator strain for the bioassay of antibiotics produced by lactic acid cocci.

Sterile glucose solution prepared by a microporous membrane bioreactor for continuous culture

Abstract Glucose solution produced in a new bioreactor with cross-flow filtration by a microporous membrane was used for continuous fermentation using Pseudomonas aeruginosa KYU-1. The membrane filtered out enzyme immobilized on corn stover for recycling. No contaminants were observed in the glucose solution by enrichment culture of the sample solution and no foreign microorganisms were detected throughout the culture.