Chemistry: molecular biology and microbiology – Micro-organism – tissue cell culture or enzyme using process... – Preparing compound containing saccharide radical
Patent
1995-09-06
1997-08-19
Rollins, John W.
Chemistry: molecular biology and microbiology
Micro-organism, tissue cell culture or enzyme using process...
Preparing compound containing saccharide radical
435100, 435101, 435105, 435200, 435209, 4352525, 435278, C12P 1914, C12N 924, C12N 120
Patent
active
056587651
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a novel xylanase, a process for producing the same, a microorganism producing the enzyme, a method for the treatment of pulp with the xylanase, and a process for producing xylose or xylo-oligosaccharide using the enzyme.
BACKGROUND ART
A xylanase is an enzyme which hydrolyzes xylan or xylan polysaccharides mainly composed of .beta.-1,4-bonded-xyloses to yield its constituents, xylose and xylo-oligosaccharide. The xylanase is present widely in animals and plants. Some microorganisms can also produce xylanases. So far investigations regarding xylanase-producing microorganisms have been made on bacteria, actinomycetes, yeasts, molds and the like.
In these years, keen attention has been brought to the use of xylanases in biomass treatment. More specifically, xylanases are used in enzymatic breakdown of agricultural wastes for production of alcoholic fuels, an enzymatic treatment of animal feeds to release free sugars, an enzymatic treatment for dissolving pulp in the preparation of cellulose and an enzymatic treatment in biobleaching of pulp. In particular, xylanase has been highly expected in the paper and pulp industry wherein xylaneses are used to enhance the brightness of bleached pulp, improve the quality of pulp, decrease the amount of chlorine used in the chemical pulp bleaching steps, and to increase the freeness of pulp in the recycled paper process.
Turning to xylose, this compound is a product of xylan hydrolysis by a xylanase and widely used as a raw material of foods and drugs. Xylo-oligosaccharide which is also a product of xylan hydrolysis is expected to be for use as a sweetener or a moisturizer.
For the use in the foregoing purposes, it is desired to prepare a xylanase suitable for mass production from inexpensive raw materials and having stability to an acid, an alkali and/or heat. Up to date, however, such a xylanase has not been achieved to meet the above requirements.
DISCLOSURE OF INVENTION
An object of the present invention is to provide a novel xylanase which is thermally stable and acts stably over a wide pH range, a process for producing the xylanase, a microorganism producing the xylanase, a method for the treatment of pulp with the xylanase, and a process for producing xylose or xylo-oligosaccharide using the xylanase.
The present inventor has made extensive investigations on enzymes and microorganisms suitable for the production of a desired xylanase satisfying the requirements as stated above. As a result, it has been found that a novel microorganism belonging to the genus Bacillus can produce a novel xylanase having physicochemical properties hitherto unknown. The present invention has thus been attained.
Accordingly, a first aspect of the present invention is xylanase 1 having the following physicochemical properties: .beta.-1,4-xylosidic linkages in the molecule to yield xylose and xylobiose in a large quantity but to yield only in a small quantity a xylo-oligosaccharide having a polymerization degree of at least that of xylotriose; has the optimum pH of about 6.0; optimum temperature of about 75.degree. C.; polyacrylamide gel electrophoresis; and,
A second aspect of the present invention is xylanase 2 having the following physicochemical properties: .beta.-1,4-xylosidic linkages in the molecule to yield xylose and to yield a xylo-oligosaccharide in a large quantity; the optimum pH of about 6.0; optimum temperature of about 65 to about 70.degree. C.; polyacrylamide gel electrophoresis; and,
A third aspect of the present invention is a process for producing a xylanase 1 or 2 which comprises culturing a microorganism belonging to the genus Bacillus and recovering the xylanase 1 or 2 from the culture medium.
A fourth aspect of the present invention is Bacillus sp. SD902 (FERM BP-4508), mutants thereof, or variants thereof obtained by Genetic engineering.
A fifth aspect of the present invention is a method for treating pulp which comprises acting a xylanase 1 or 2.
A sixth aspect of the present invention is a method for produc
REFERENCES:
Gruninger et al, "A Novel, Highly Thermostable D-Xylanase", Enzyme Microb. Technol., vol. 8, 309-314 (1986).
Rajaram et al, "Production and Characterization of Xylanase from Bacillus Thermoalkalophilus Grown On Agricultural Wastes", Applied Microbiology Biotechnology 34, 141-144 (1990).
Nanmori et al, "Purification and Properties of Thermostable Xylanase and B-Xylosidase Produced by a Newly Isolated Bacillus Stearothermophilus Strain", J. Bacteriol., 172, 6669-6672 (1992).
Dey et al, "Purification and Properties of Extracellular Endoxylanases from Alkalophilic Thermophilic Bacillus sp." Can. J. Microbiol., 38, 436-442 (1992).
Khasin et al, "Purification and Characterization of a Thermostable Xylanase from Bacillus Stearothermophilus T-6", Appl. Environ. Microbiol., 59, 1725-1730 (1993).
Nakamura et al "Thermophilic Alkaline Xylanase from Newly Isolated Alkaliphilic and Thermophilic Bacillus sp. Strain TAR-1", Biosci. Biotech. Biochem 58(1), 78-81, 1994.
Alam et al, "Production and Characterization of Themostable Xylanases by Thermomyces Languginosus and Thermoascus Aurantiacus Grown on Lignocelluloses, Enzyme Microb. Technol.", 1994 vol. 16, Apr.
Gupta et al, "A Thermostable Extracellular Xylanase from Alkalophilic Bacillus sp. NG-27", Biotechnology Letters, vol. 14, No. 11 (Nov.1992) pp. 1045-1046.
Okazaki et al, "Purification and Characterization of Xylanases from Alkalophilic Thermophilic Bacillus spp." Agric. Biol. Chem., 49(7), 2033-2039, 1985.
Ikeda Kazuko
Masatsuji Eiko
Noguchi Yoshitaka
Seko Masahiko
Gregg, Esq. Valeta A.
Novo Nordisk A S
Prats Francisco C.
Rollins John W.
Zelson Esq. Steve T.
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