title: Synergy of crude enzyme cocktail from cold-adapted Cladosporium cladosporioides Ch2-2 with commercial xylanase achieving high sugars yield at low cost.
abstract: BACKGROUND
  The efficiency and cost of current lignocellulosic enzymes still limit the large-scale production of cellulosic ethanol in industry. Residual lignin after pretreatment severely depresses the activity of polysaccharide hydrolases and the h ydrolysis of holocellulose. If we include in hydrolase mixture construction the ligninase involved in lignin degradation, which mainly includes laccase, manganese peroxidases (MnP) and lignin peroxidase (LiP), it is feasible that this could greatly improve the fermentable sugars yield.
  
  
  RESULTS
  The psychrophilic lignocellulosic enzymes system of Cladosporium cladosporioides Ch2-2 including ligninase and polysaccharide hydrolases was suitable for selective delignification and efficient saccharification of biomass with wide thermal adaptability. The purified laccase was optimally active at 15°C and pH 3.5, exhibiting high thermostability over a broad range of temperatures (between 4 and 40°C). In addition, manganese-independent peroxidase (MIP), a special type of ligninase with the capacity to oxidize dimethyl phthalate (DMP) in the absence of H2O2 and Mn(2+), was optimally active at 20°C and pH 2.5, exhibiting high thermostability over a broad range of temperatures (4 and 28°C), while depressed completely by Fe(2+) and essentially unaffected by EDTA. Synergy between Ch2-2 crude enzymes and commercial xylanase obviously enhanced biomass hydrolysis, which could take the place of expensive commercial cellulase mixture. The maximum value of synergistic degree reached 4.7 at 28°C, resulting in 10.1 mg/mL reducing sugars.
  
  
  CONCLUSIONS
  The psychrophilic enzymes system of C. cladosporioides Ch2-2 with a different synergistic mechanism has huge potential for the enhancement of biomass hydrolysis at mesophilic and low temperatures. The application scope of the lignocellulosic enzyme cocktail could be greatly enlarged by optimizing the operation conditions specific to the characteristics of ligninase.
authors.affiliation: State Key Laboratory of Agrobiotechnology, MOA Key Laboratory of Soil Microbiology and National Energy R & D Center for Non-food Biomass, College of Biological Sciences, China Agricultural University, Beijing, 100193 China.
authors.forename: Lei
authors.initials: L
authors.lastname: Ji
authors.affiliation: State Key Laboratory of Agrobiotechnology, MOA Key Laboratory of Soil Microbiology and National Energy R & D Center for Non-food Biomass, College of Biological Sciences, China Agricultural University, Beijing, 100193 China.
authors.forename: Jinshui
authors.initials: J
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Agrobiotechnology, MOA Key Laboratory of Soil Microbiology and National Energy R & D Center for Non-food Biomass, College of Biological Sciences, China Agricultural University, Beijing, 100193 China.
authors.forename: Hua
authors.initials: H
authors.lastname: Fan
authors.affiliation: State Key Laboratory of Agrobiotechnology, MOA Key Laboratory of Soil Microbiology and National Energy R & D Center for Non-food Biomass, College of Biological Sciences, China Agricultural University, Beijing, 100193 China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Agrobiotechnology, MOA Key Laboratory of Soil Microbiology and National Energy R & D Center for Non-food Biomass, College of Biological Sciences, China Agricultural University, Beijing, 100193 China.
authors.forename: Baozhen
authors.initials: B
authors.lastname: Li
authors.affiliation: State Key Laboratory of Agrobiotechnology, MOA Key Laboratory of Soil Microbiology and National Energy R & D Center for Non-food Biomass, College of Biological Sciences, China Agricultural University, Beijing, 100193 China.
authors.forename: Xuejian
authors.initials: X
authors.lastname: Yu
authors.affiliation: State Key Laboratory of Agrobiotechnology, MOA Key Laboratory of Soil Microbiology and National Energy R & D Center for Non-food Biomass, College of Biological Sciences, China Agricultural University, Beijing, 100193 China.
authors.forename: Ning
authors.initials: N
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Agrobiotechnology, MOA Key Laboratory of Soil Microbiology and National Energy R & D Center for Non-food Biomass, College of Biological Sciences, China Agricultural University, Beijing, 100193 China.
authors.forename: Hongli
authors.initials: H
authors.lastname: Yuan
keywords: Cladosporium cladosporioides; Cold adaptation; Commercial xylanase; Laccase; MIP; Polysaccharide hydrolases; Synergy