title: Endoglucanase enzymatic modification of kraft pulp during recycling.
abstract: OBJECTIVE
  To investigate the cellulose modification process on kraft pulp during recycling by mono-endoglucanase.
  
  
  RESULTS
  Pichia pastoris expressing endoglucanase, EG1, was grown in a 10 l fermenter yielding a high carboxymethyl cellulase (CMCase) activity of 340 U mg(-1). EG1-mediated modification of kraft pulp resulted in a paper sheet with the tensile index and burst index increased by 10 and 6.5 %, respectively. The kink index (indicating abrupt bends in fibres) of the enzyme-treated group decreased sharply by 45 % after the first recycling, compared with a reduction of only 1 % in the control group. Furthermore, EG1 treatment decreased the growth of crystallinity from 73.5 to 73.2 % and crystal size from 7.45 to 7.21 nm, which alleviated paper aging.
  
  
  CONCLUSIONS
  Endoglucanase EG1 modifies the interfacial properties of fibers, which affects fibre morphology during the recycling process and improves the technical properties of the resulting pulp and paper.
authors.affiliation: School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, Guangdong, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Deng
authors.affiliation: School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, Guangdong, China.
authors.forename: Liuliu
authors.initials: L
authors.lastname: Lu
authors.affiliation: School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, Guangdong, China.
authors.forename: Shipeng
authors.initials: S
authors.lastname: Gao
authors.affiliation: School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, Guangdong, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Lin
authors.affiliation: School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, Guangdong, China. syhan@scut.edu.cn.
authors.forename: Shuangyan
authors.initials: S
authors.lastname: Han
mesh_terms: D002480:Cellulase / Q000378:metabolism*; D010209:Paper; D010843:Pichia / Q000201:enzymology
chemical_list: D002480:Cellulase; C019826:carboxymethylcellulase
keywords: Carboxymethyl cellulase; Crystallinity; Endoglucanase EG1; Kraft pulp treatment; Pichia pastoris; Recycling; Volvariella volvacea