title: Salt-responsive lytic polysaccharide monooxygenases from the mangrove fungus Pestalotiopsis sp. NCi6.
abstract: BACKGROUND
  Lytic polysaccharide monooxygenases (LPMOs) belong to the "auxiliary activities (AA)" enzyme class of the CAZy database. They are known to strongly improve the saccharification process and boost soluble sugar yields from lignocellulosic biomass, which is a key step in the efficient production of sustainable economic biofuels. To date, most LPMOs have been characterized from terrestrial fungi, but novel fungal LPMOs isolated from more extreme environments such as an estuary mangrove ecosystem could offer enzymes with unique properties in terms of salt tolerance and higher stability under harsh condition.
  
  
  RESULTS
  Two LPMOs secreted by the mangrove-associated fungus Pestalotiopsis sp. NCi6 (PsLPMOA and PsLPMOB) were expressed in the yeast Pichia pastoris and produced in a bioreactor with >85 mg L(-1) for PsLPMOA and >260 mg L(-1) for PsLPMOB. Structure-guided homology modeling of the PsLPMOs showed a high abundance of negative surface charges, enabling enhanced protein stability and activity in the presence of sea salt. Both PsLPMOs were activated by a cellobiose dehydrogenase (CDH) from Neurospora crassa, with an apparent optimum of interaction at pH 5.5. Investigation into their regioselective mode of action revealed that PsLPMOA released C1- and C4-oxidized cello-oligosaccharide products, while PsLPMOB released only C4-oxidized products. PsLPMOA was found to cleave polymeric cellulose in the presence of up to 6 % sea salt, which emphasizes the use of sea water in the industrial saccharification process with improved ecological footprints.
  
  
  CONCLUSIONS
  Two new LPMOs from the mangrove fungus Pestalotiopsis sp. NCi6 were found to be fully reactive against cellulose. The combined hydrolytic activities of these salt-responsive LPMOs could therefore facilitate the saccharification process using sea water as a reaction medium for large-scale biorefineries.
authors.affiliation: INRA, UMR1163 Biodiversité et Biotechnologie Fongiques, Aix-Marseille Université, Polytech Marseille, 163 Avenue de Luminy, CP 925, 13288 Marseille Cedex 09, France ; UMR1163 Biodiversité et Biotechnologie Fongiques, Faculté des Sciences de Luminy-Polytech Marseille, Aix-Marseille Université, 163 Avenue de Luminy, CP 925, 13288 Marseille Cedex 09, France.
authors.forename: Ilabahen
authors.initials: I
authors.lastname: Patel
authors.affiliation: Department of Food Sciences and Technology, Food Biotechnology Laboratory, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, Vienna, 1190 Austria.
authors.forename: Daniel
authors.initials: D
authors.lastname: Kracher
authors.affiliation: Department of Food Sciences and Technology, Food Biotechnology Laboratory, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, Vienna, 1190 Austria.
authors.forename: Su
authors.initials: S
authors.lastname: Ma
authors.affiliation: INRA, UMR1163 Biodiversité et Biotechnologie Fongiques, Aix-Marseille Université, Polytech Marseille, 163 Avenue de Luminy, CP 925, 13288 Marseille Cedex 09, France ; UMR1163 Biodiversité et Biotechnologie Fongiques, Faculté des Sciences de Luminy-Polytech Marseille, Aix-Marseille Université, 163 Avenue de Luminy, CP 925, 13288 Marseille Cedex 09, France.
authors.forename: Sona
authors.initials: S
authors.lastname: Garajova
authors.affiliation: INRA, UMR1163 Biodiversité et Biotechnologie Fongiques, Aix-Marseille Université, Polytech Marseille, 163 Avenue de Luminy, CP 925, 13288 Marseille Cedex 09, France ; UMR1163 Biodiversité et Biotechnologie Fongiques, Faculté des Sciences de Luminy-Polytech Marseille, Aix-Marseille Université, 163 Avenue de Luminy, CP 925, 13288 Marseille Cedex 09, France.
authors.forename: Mireille
authors.initials: M
authors.lastname: Haon
authors.affiliation: INRA, UMR1163 Biodiversité et Biotechnologie Fongiques, Aix-Marseille Université, Polytech Marseille, 163 Avenue de Luminy, CP 925, 13288 Marseille Cedex 09, France ; UMR1163 Biodiversité et Biotechnologie Fongiques, Faculté des Sciences de Luminy-Polytech Marseille, Aix-Marseille Université, 163 Avenue de Luminy, CP 925, 13288 Marseille Cedex 09, France.
authors.forename: Craig B
authors.initials: CB
authors.lastname: Faulds
authors.affiliation: INRA, UMR1163 Biodiversité et Biotechnologie Fongiques, Aix-Marseille Université, Polytech Marseille, 163 Avenue de Luminy, CP 925, 13288 Marseille Cedex 09, France ; UMR1163 Biodiversité et Biotechnologie Fongiques, Faculté des Sciences de Luminy-Polytech Marseille, Aix-Marseille Université, 163 Avenue de Luminy, CP 925, 13288 Marseille Cedex 09, France.
authors.forename: Jean-Guy
authors.initials: JG
authors.lastname: Berrin
authors.affiliation: Department of Food Sciences and Technology, Food Biotechnology Laboratory, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, Vienna, 1190 Austria.
authors.forename: Roland
authors.initials: R
authors.lastname: Ludwig
authors.affiliation: INRA, UMR1163 Biodiversité et Biotechnologie Fongiques, Aix-Marseille Université, Polytech Marseille, 163 Avenue de Luminy, CP 925, 13288 Marseille Cedex 09, France ; UMR1163 Biodiversité et Biotechnologie Fongiques, Faculté des Sciences de Luminy-Polytech Marseille, Aix-Marseille Université, 163 Avenue de Luminy, CP 925, 13288 Marseille Cedex 09, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Record
keywords: AA9; Biorefinery; Cellobiose dehydrogenase; Cellulose; LPMO