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Production of a cloned xylanase in Bacillus cereus and its performance in kraft pulp prebleaching
- Source :
- Canadian journal of microbiology. 39(9)
- Publication Year :
- 1993
-
Abstract
- Xylanase production from a Bacillus subtilis gene cloned into a strain of Escherichia coli was monitored. Although this gene was expressed in E. coli at several temperatures, efficient xylanase secretion did not occur; the observed protein release apparently depended on cell leakage or lysis. Screening for a better microbial protein secretor free of cellulase selected Bacillus cereus No. 518. A bidirectional vector plasmid (pMK3) was employed to carry the cloned gene into this B. cereus strain. Transformation was carried out by electroporation. Total xylanase production by the new pMK3-borne gene in B. cereus was similar to that from E. coli but the xylanase was shown to be normally secreted. The xylanase gene products from the E. coli and B. cereus hosts were shown to function identically. Both xylanases improved the delignification of unbleached softwood and hardwood kraft pulps, thus reducing the Cl2 required to achieve a given degree of bleaching, without altering the physical properties of the fibers. Using a target kappa number (lignin content) of 5, xylanase pretreatment of aspen kraft (chemical) pulp led to a 22% savings of chlorine. Adsorbable organic halogens in the bleachery effluent were also lowered by more than 50%.Key words: Bacillus subtilis, endoxylanase gene, bleaching, kraft pulp properties.
- Subjects :
- Paper
Glycoside Hydrolases
Immunology
Bacillus cereus
Cellulase
Bacillus subtilis
medicine.disease_cause
Applied Microbiology and Biotechnology
Microbiology
Lignin
Trees
Transformation, Genetic
Genetics
medicine
Escherichia coli
Cloning, Molecular
Molecular Biology
biology
General Medicine
biology.organism_classification
Xylan Endo-1,3-beta-Xylosidase
Cereus
Kraft process
Biochemistry
Chemical Industry
biology.protein
Xylanase
Kraft paper
Plasmids
Subjects
Details
- ISSN :
- 00084166
- Volume :
- 39
- Issue :
- 9
- Database :
- OpenAIRE
- Journal :
- Canadian journal of microbiology
- Accession number :
- edsair.doi.dedup.....5f5de350eca5d80819619da69e1011e2