自然界から分離された細菌の産生するβ-Mannanase〔英文〕

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The culture fluids of 117 bacterial strains isolated from natural habitats were assayed for β-mannanase activity by using codium mannan as a substrate. The highest β-mannanase productivity was detected in the strain F-25 of Aeromonas sp. isolated from the intestinal contents of freshwater fish, Salmo gairdnerii. β-Mannanase form the strain was induced enzyme. Konjac glucomannan and commercially available konjac powder were superior inducers. The β-mannanase productivity of the strain was susceptible to the influence of culture temperature; the strain showed the highest β-mannanase activity when incubated at 25°C for 3 days, but hardly showed the activity at 37°C. The culture fluid of Aeromonas sp. F-25 was separated into two fractions with β-mannanase activity by DEAE-Sephadex A-50 column chromatography. One fraction eluted by a salt gradient contained an endo-β-mannanase, which hydrolyzed codium mannan, coffee mannan, konjac glucomanna and guar gum galactomannan to give several mannooligosaccharides. The other fraction eluted through the column without adsorption contained an exo-β-mannanase of novel type, which attacked codium mannan and coffee mannan to form only mannobiose but not konjac glucomannan and guar gum galactomannan.
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