Chemistry: molecular biology and microbiology – Enzyme – proenzyme; compositions thereof; process for... – Hydrolase
Patent
1993-02-02
1995-10-10
Low, Christopher S. F.
Chemistry: molecular biology and microbiology
Enzyme , proenzyme; compositions thereof; process for...
Hydrolase
435200, 4353201, 4351723, C12N 926
Patent
active
054570450
DESCRIPTION:
BRIEF SUMMARY
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation of PCT/DK91/00242 filed Aug. 23, 1991, which is incorporated herein by reference.
FIELD OF THE INVENTION
This invention relates to novel enzymes possessing xylanolytic activity. More specifically, the invention relates to novel xylanases obtainable from strains of Bacillus pumilus, a process for their preparation, and the use of these xylanases for treatment of lignocellulosic pulp.
BACKGROUND ART
Members of Bacillus pumilus are known and described in the literature, and it is known that they are able to produce xylanases.
A specific isolate from soil in Thailand, B. pumilus IPO, has been thoroughly described by Panbangred et al. (1983); J. Agric. Biol. Chem.; 47(5), 957-963; and Fukusaki et al. (1984); FEBS Lett.; 171(2), 197-201. In JP Patent Specification No. 86039036, this B. pumilus IPO xylanase is provided by way of recombinant DNA technology. The specification mentions the use of this enzyme in the decomposition of xylan contained in animal feed or in clarification of muddy wines or fruit juices. There is given no indication of its usefulness in the treatment of lignocellulosic pulp.
SUMMARY OF THE INVENTION
Now a novel xylanase obtainable from a strain of B. pumilus has been elucidated. The xylanase of this invention possesses excellent properties for treatment of lignocellulosic pulp.
Accordingly, in its first aspect, the present invention provides xylanases comprising specified partial amino acid sequences, and having immunochemical properties identical or partially identical to those of a xylanase derived from the strain DSM, No. 6124.
In another aspect, the invention provides xylanases comprising specified partial amino acid sequences, and being obtainable from strains of Bacillus pumilus, or a mutant or a variant thereof.
The invention also provides a method of producing the xylanases, comprising cultivation of a strain of B. pumilus, or a mutant or a variant thereof, in a nutrient medium containing assimilable carbon and nitrogen together with other essential nutrient, followed by recovery of the desired enzyme.
In a further aspect, the invention provides a method of producing the xylanases, comprising isolating a DNA fragment encoding the xylanase; combining the DNA fragment with an appropriate expression signal in an appropriate plasmid vector; introducing the plasmid vector into an appropriate host either as an autonomously replicating plasmid or integrated into the chromosome; cultivating the host organism under conditions leading to expression of the xylanase; and recovering the xylanase from the culture medium.
Moreover, the invention relates to the use of the xylanases in the treatment of lignocellulosic pulp. In a more specific aspect, the invention provides a process for treatment of lignocellulosic chemical pulp, wherein the lignocellulosic pulp is treated with the xylanase at a pH of above 6.5, preferably above 7.5, whereafter the thus treated cellulosic pulp is treated with chlorine at an active chlorine multiple of 0.20 or less in the first chlorination stage.
BRIEF DESCRIPTION OF DRAWINGS
The present invention is further illustrated by reference to the accompanying drawings, in which:
FIG. 1 shows a comparison of the amino acid sequence of the B. pumilus IPO xylanase according to Fukusaki et al. (1984), op. cit. (the upper sequence (SEQ I.D. No: 1) and the partial amino acid sequence of the xylanase of the invention (the lower sequence (SEQ. I.D. Nos. 2-4) the amino acids are indicated in the established one-letter code;
FIG. 2 shows the pH profile of a xylanase of the invention;
FIG. 3 shows the temperature profile of a xylanase of the invention; and
FIG. 4 shows a comparison of the amino acid sequence of the B. pumilus IPO xylanase according to Fukusaki et al. (1984), op. cit. (the upper sequence (SEQ. I.D. No. 1) and the partial amino acid sequence of the xylanase of the invention (the lower sequence (SEQ. I.D. Nos. 2, 3 and 5-8) the amino acids are indicated in the established one-letter
REFERENCES:
Okada et al., Chemical Abstracts, vol. 109, No. 25, p. 340, Abstract No. 225224v, 1988.
Moriyama et al., Chemical Abstracts, vol. 107, No. 25, p. 199, Abstract No. 230230g.
Noe et al., Chemical Abstracts vol. 105, No. 10, p. 115, Abstract No. 80961p.
Fukusaki et al., FEBS, vol. 171, No. 2, pp. 197-201, Jun. 1984.
Paice et al., Biotechnology and Bioengineering, vol. 32, pp. 235-239, 1988.
D. J. Senior et al., Biotechnology and Bioengineering, vol. 37, pp. 274-270, 1991.
W. Panbangred et al., Agric. Biol. Chem., vol. 47, No. 5, pp. 957-963, 1983.
Akiba et al. 1988 Meth. Enzymol. 160, 655-659.
Sjoblom et al. "Reduced Discharge of TOCI with a Hot (EO) Stage") 1988 Int'l-Pulp Bleaching Conf. Jun. 5-9, 1988 Orlando, Fla.
Anker Lisbeth
Bisgard-Frantzen Henrik
Halkier Torben
Lambiris Elias J.
Low Christopher S. F.
Novo Nordisk A S
Zelson Steve T.
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