title: Hyperthermophilic endoglucanase for in planta lignocellulose conversion.
abstract: BACKGROUND
  The enzymatic conversion of lignocellulosic plant biomass into fermentable sugars is a crucial step in the sustainable and environmentally friendly production of biofuels. However, a major drawback of enzymes from mesophilic sources is their suboptimal activity under established pretreatment conditions, e.g. high temperatures, extreme pH values and high salt concentrations. Enzymes from extremophiles are better adapted to these conditions and could be produced by heterologous expression in microbes, or even directly in the plant biomass.
  
  
  RESULTS
  Here we show that a cellulase gene (sso1354) isolated from the hyperthermophilic archaeon Sulfolobus solfataricus can be expressed in plants, and that the recombinant enzyme is biologically active and exhibits the same properties as the wild type form. Since the enzyme is inactive under normal plant growth conditions, this potentially allows its expression in plants without negative effects on growth and development, and subsequent heat-inducible activation. Furthermore we demonstrate that the recombinant enzyme acts in high concentrations of ionic liquids and can therefore degrade α-cellulose or even complex cell wall preparations under those pretreatment conditions.
  
  
  CONCLUSIONS
  The hyperthermophilic endoglucanase SSO1354 with its unique features is an excellent tool for advanced biomass conversion. Here we demonstrate its expression in planta and the possibility for post harvest activation. Moreover the enzyme is suitable for combined pretreatment and hydrolysis applications.
authors.affiliation: Institute for Molecular Biotechnology (Biology VII), RWTH Aachen University, Worringerweg 1, 52074, Aachen, Germany. commandeur@molbiotech.rwth-aachen.de.
authors.forename: Holger
authors.initials: H
authors.lastname: Klose
authors.forename: Juliane
authors.initials: J
authors.lastname: Röder
authors.forename: Michele
authors.initials: M
authors.lastname: Girfoglio
authors.forename: Rainer
authors.initials: R
authors.lastname: Fischer
authors.forename: Ulrich
authors.initials: U
authors.lastname: Commandeur