Aspen pectate lyase PtxtPL1-27 mobilizes matrix polysaccharides from woody tissues and improves saccharification yield.
BACKGROUND
Wood cell walls are rich in cellulose, hemicellulose and lignin. Hence, they are important sources of renewable biomass for producing energy and green chemicals. However, extracting desired constituents from wood efficiently poses significant challenges because these polymers are highly cross-linked in cell walls and are not easily accessible to enzymes and chemicals.


RESULTS
We show that aspen pectate lyase PL1-27, which degrades homogalacturonan and is expressed at the onset of secondary wall formation, can increase the solubility of wood matrix polysaccharides. Overexpression of this enzyme in aspen increased solubility of not only pectins but also xylans and other hemicelluloses, indicating that homogalacturonan limits the solubility of major wood cell wall components. Enzymatic saccharification of wood obtained from PL1-27-overexpressing trees gave higher yields of pentoses and hexoses than similar treatment of wood from wild-type trees, even after acid pretreatment.


CONCLUSIONS
Thus, the modification of pectins may constitute an important biotechnological target for improved wood processing despite their low abundance in woody biomass.
Ajaya K
AK
Biswal
Kazuo
K
Soeno
Madhavi Latha
ML
Gandla
Peter
P
Immerzeel
Sivakumar
S
Pattathil
Jessica
J
Lucenius
Ritva
R
Serimaa
Michael G
MG
Hahn
Thomas
T
Moritz
Leif J
LJ
Jönsson
Maria
M
Israelsson-Nordström
Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, S901 83 Umeå, Sweden. Ewa.Mellerowicz@slu.se.
Ewa J
EJ
Mellerowicz