%0 Journal Article
%T Engineering Escherichia coli for succinate production from hemicellulose via consolidated bioprocessing
%A Zongbao Zheng
%A Tao Chen
%A Meina Zhao
%A Zhiwen Wang
%A Xueming Zhao
%J Microbial Cell Factories
%D 2012
%I BioMed Central
%R 10.1186/1475-2859-11-37
%X Xylanases were extracellular environment-directed by fusing with OsmY. Subsequently, twelve variant OsmY fused endoxylanase-xylosidase combinations were characterized and tested. The combination of XynC-A from Fibrobacter succinogenes S85 and XyloA from Fusarium graminearum which appeared to have optimal enzymatic properties was identified as the best choice for xylan hydrolysis (0.18 ¡À 0.01 g/l protein in the broth with endoxylanase activity of 12.14 ¡À 0.34 U/mg protein and xylosidase activity of 92 ¡À 3 mU/mg protein at 8 h after induction). Further improvements of hemicellulases secretion were investigated by lpp deletion, dsbA overexpression and expression level optimization. With co-expression of ¦Á-arabinofuranosidase, the engineered E. coli could hydrolyze beechwood xylan to pentose monosaccharides. The hemicellulolytic capacity was further integrated with a succinate-producing strain to demonstrate the production of succinate directly from xylan without externally supplied hydrolases and any other organic nutrient. The resulting E. coli Z6373 was able to produce 0.37 g/g succinate from xylan anaerobically equivalent to 76% of that from xylan acid hydrolysates.This report represents a promising step towards the goal of hemicellulosic chemical production. This engineered E. coli expressing and secreting three hemicellulases demonstrated a considerable succinate production on the released monosaccharides from xylan. The ability to use lower-cost crude feedstock will make biological succinate production more economically attractive.Lignocellulosic biomass represents an abundant, low-cost and renewable source of fermentable sugars. It is an alternative candidate besides petroleum as feedstock for fuel and chemical production [1]. Generally, lignocellulosic biomass comprises of 35-50% cellulose, 20-35% hemicellulose and 10-25% lignin [2]. As the major component of hemicellulose, xylan is one of the most abundant natural polysaccharides with a ¦Â-(1, 4)-linked xylose
%K Consolidated bioprocessing
%K Escherichia coli
%K Hemicellulose
%K Succinate
%K Xylan
%U http://www.microbialcellfactories.com/content/11/1/37