Heterologous expression of Pycnoporus cinnabarinuscellobiose dehydrogenase in Pichia pastorisand involvement in saccharification processes

Bey Mathieu, Berrin Jean-Guy, Poidevin Laetitia, Sigoillot, Sigoillot Jean-Claude

Description

Cellobiose dehydrogenase (CDH) is an extracellular hemoflavoenzyme produced by lignocellulose-degrading fungi including Pycnoporus cinnabarinus . We investigated the cellulolytic system of P. cinnabarinus , focusing on the involvement of CDH in the deconstruction of lignocellulosic biomass. Results First, P. cinnabarinus growth conditions were optimized for CDH production. Following growth under cellulolytic conditions, the main components secreted were cellulases, xylanases and CDH. To investigate the contribution of P. cinnabarinus secretome in saccharification processes, the Trichoderma reesei enzymatic cocktail was supplemented with the P. cinnabarinus secretome. A significant enhancement of the degradation of wheat straw was observed with (i) the production of a large amount of gluconic acid, (ii) increased hemicellulose degradation, and (iii) increased overall degradation of the lignocellulosic material. P. cinnabarinus CDH was heterologously expressed in Pichia pastoris to obtain large amounts of pure enzyme. In a bioreactor, the recombinant CDH (rCDH) expression level reached 7800 U/L. rCDH exhibited values of biochemical parameters similar to those of the natural enzyme, and was able to bind cellulose despite the absence of a carbohydrate-binding module (CBM). Following supplementation of purified rCDH to T. reesei enzymatic cocktail, formation of gluconic acid and increased hemicellulose degradation were observed, thus confirming the previous results observed with P. cinnabarinus secretome. Conclusions We demonstrate that CDH offers an attractive tool for saccharification process enhancement due to gluconic acid production from raw lignocellulosic material.

Sujets

• CDH
• Gluconic acid
• Lignocellulose
• Biomass
• Saccharification

Informations

• Publié par: biomed
• Publié le: 01 janvier 2011
• Nombre de lectures: 34
• Langue: English

Extrait

Bey et al . Microbial Cell Factories 2011, 10 :113 http://www.microbialcellfactories.com/content/10/1/113

R E S E A R C H Open Access Heterologous expression of Pycnoporus cinnabarinus cellobiose dehydrogenase in Pichia pastoris and involvement in saccharification processes Mathieu Bey 1,2* , Jean-Guy Berrin 1,2 , Laetitia Poidevin 1,2,3 and Jean-Claude Sigoillot 1,2

Abstract Background: Cellobiose dehydrogenase (CDH) is an extracellular hemoflavoenzyme produced by lignocellulose- degrading fungi including Pycnoporus cinnabarinus . We investigated the cellulolytic system of P. cinnabarinus , focusing on the involvement of CDH in the deconstruction of lignocellulosic biomass. Results: First, P. cinnabarinus growth conditions were optimized for CDH production. Following growth under cellulolytic conditions, the main components secreted were cellulases, xylanases and CDH. To investigate the contribution of P. cinnabarinus secretome in saccharification processes, the Trichoderma reesei enzymatic cocktail was supplemented with the P. cinnabarinus secretome. A significant enhancement of the degradation of wheat straw was observed with (i) the production of a large amount of gluconic acid, (ii) increased hemicellulose degradation, and (iii) increased overall degradation of the lignocellulosic material. P. cinnabarinus CDH was heterologously expressed in Pichia pastoris to obtain large amounts of pure enzyme. In a bioreactor, the recombinant CDH (rCDH) expression level reached 7800 U/L. rCDH exhibited values of biochemical parameters similar to those of the natural enzyme, and was able to bind cellulose despite the absence of a carbohydrate- binding module (CBM). Following supplementation of purified rCDH to T. reesei enzymatic cocktail, formation of gluconic acid and increased hemicellulose degradation were observed, thus confirming the previous results observed with P. cinnabarinus secretome. Conclusions: We demonstrate that CDH offers an attractive tool for saccharification process enhancement due to gluconic acid production from raw lignocellulosic material. Keywords: White-rot fungi, CDH, gluconic acid, lignocellulose, biomass, saccharification

Background enzymes, phenolic acid esterase, and possibly lignin- In natural environments, cellulolytic microorganisms  degrading and modifying enzymes [1]. secrete enzymes that function synergistically, in associa- The main industrial source of cellulases and hemicel- tion with the microorganism or independently. Although lulases is the mesophilic soft-rot fungus T. reesei (teleo- it is not fully known how many enzymes are involved in morph Hypocrea jecorina ), valued for the high protein cell wall deconstruction, three general categories of secretion capacity of its mutant strains obtained by ran- enzymes are considered necessary to hydrolyze native dom mutagenesis (producing up to 100 g of extracellu- cell wall materials: cellulases, hemicellulases and acces-  lar protein per liter of culture) [2,3]. sory enzymes such as hemicellulose debranching Among fungal classes, basidiomycetes are known to be efficient degraders of cellulose, many species growing on dead wood or litter. The lignocellulolytic system of basi- hieu @esil.univmed.fr s has been studied intensively in the last dec- * 1 IN C R or A r , es U p M o R n 1 d 1 e 6 n 3 ce B : C m F, at 163a . v b e e n y uedeLuminy,13288Marseille,France a d d io es m . y G c e et n e omesequencingandproteomictoolsareoften Full list of author information is available at the end of the article © 2011 Bey et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.