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Zheng Z.,Nanjing Forestry University | Zheng Z.,Jiangsu Key Laboratory of Biomass based Green Fuels and Chemicals | Xu Y.,Nanjing Forestry University | Sun Y.,Nanjing Forestry University | And 3 more authors.
PLoS ONE | Year: 2015

Trehalose is a non-reducing disaccharide, which can protect proteins, lipid membranes, and cells from desiccation, refrigeration, dehydration, and other harsh environments. Trehalose can be produced by different pathways and trehalose synthase pathway is a convenient, practical, and low-cost pathway for the industrial production of trehalose. In this study, 3 candidate treS genes were screened from genomic databases of Pseudomonas and expressed in Escherichia coli. One of them from P. stutzeri A1501 exhibited the best transformation ability from maltose into trehalose and the least byproduct. Thus, whole cells of this recombinant E. coli were used as biocatalyst for trehalose production. In order to improve the conversion rate of maltose to trehalose, optimization of the permeabilization and biotransformation were carried out. Under optimal conditions, 92.2 g/l trehalose was produced with a high productivity of 23.1 g/(l h). No increase of glucose was detected during the whole course. The biocatalytic process developed in this study might serve as a candidate for the large scale production of trehalose. Copyright: © 2015 Zheng et al.This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


Xu Y.,Nanjing Forestry University | Xu Y.,Key Laboratory of Forest Genetics and Biotechnology | Xu Y.,Jiangsu Key Laboratory of Biomass based Green Fuels and Chemicals | Fan L.,Nanjing Forestry University | And 9 more authors.
BioResources | Year: 2013

A simple one-step method was developed for rapid separation and quantification of the linear xylo-oligosaccharides (XOS) and cello-oligosaccharides (COS) mixtures by using high-performance anion-exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD). By exploiting small ion-exchange behavioral differences of various oligosaccharide components on the CarboPac PA200 column, a two-stage binary gradient elution program of NaOAc-NaOH solution was established. Subsequently, nine linear oligomers were separated simultaneously and readily within 30 min, in the order of: xylobiose, cellobiose, xylotriose, xylotetraose, cellotriose, xylopentaose, cellotetraose, xylohexaose, and cellopentaose. The method was applied successfully in the analysis and determination of different lignocellulosics processing products. The system provides a convenient and powerful analytical tool for technical research and development on polysaccharide components bioconversion in lignocellulosic biomass processing.


Zhou X.,Nanjing Forestry University | Zhou X.,Key Laboratory of Forest Genetics and Biotechnology | Lu S.,Nanjing Forestry University | Lu S.,Key Laboratory of Forest Genetics and Biotechnology | And 6 more authors.
Biochemical Engineering Journal | Year: 2015

Xylonic acid is useful and producing it in bacteria cost-effectively would be good because of potential applications and high yield. Production in bacteria like Gluconobacter oxydans is hampered by low xylose utilization and poor bacterial tolerance to contaminants. Here we exploited the oxygen-dependence of NAD+ regeneration and the lack of gas release during xylose metabolism in G. oxydans to develop a high-oxygen tension bioreactor with increased productivity. In this design we maintained gas outlets closed, which eliminated all bubbling and media foaming, and added a compressed pure oxygen inlet, which increased oxygen tension. Biocatalysis of xylose in this bioreactor yielded 3 times higher (586.3g/L xylonic acid) than the best previous output. Moreover, we directly produced 143.9g/L of xylonic acid from the diluted sulfuric acid pre-hydrolysates of corn stover without a detoxification process and at 1.0g/L/h volumetric productivity. The central features of this bioreactor design are scalable and thus would enable cost-competitive bacterial xylonic acid production. © 2014 Elsevier B.V.


Jiang F.-X.,Nanjing Forestry University | Jiang F.-X.,Key Laboratory of Forest Genetics and Biotechnology | Jiang F.-X.,Jiangsu Key Laboratory of Biomass based Green Fuels and Chemicals | Xu Y.,Nanjing Forestry University | And 8 more authors.
Chemistry and Industry of Forest Products | Year: 2015

Four main non-lignin constituents in corn stover, including cellulose, hemicellulose, hot water extractives, and ethanol extractives, were prepared and pretreated with dilute sulfuric acid, respectively. Their water soluble degradation products profiles were analyzed by high performance liquid chromatography detection. During dilute sulfuric acid pretreatment, glucose, formic acid (FA), levulinic acid (LA), and 5-hydroxymethylfurfural (HMF) were released from cellulose degradation. Xylose, arabinose, glucuronic acid, galacturonic acid, acetic acid (AA), and furfural were released from hemicellulose degradation. The hot water extractives degradation produced glucose, xylose, arabinose, FA, AA, LA, HMF, and furfural, and only trace of glucose, xylose, AA, LA, and HMF were found in the hydrolyzates of ethanol extractives. Totally, FA, LA, and HMF mainly originated from cellulose degradation at the yields of 1.4%, 2.7%, and 2.2%, while AA and furfural came from hemicellulose degradation at the yields of 3.1% and 7.8% on the basis of corn stove weight, respectively. Orthogonal tests showed that the AA production was significantly affected by the concentration of sulfuric acid, while the FA, LA, HMF, and furfural formations were seriously affected by the pretreatment temperature. ©, 2015, Edited & Published by Editorial Board of «Chemistry and Industry of Forest Products». All right reserved.


Jiang F.-X.,Nanjing Forestry University | Jiang F.-X.,Key Laboratory of Forest Genetics and Biotechnology | Jiang F.-X.,Jiangsu Key Laboratory of Biomass based Green Fuels and Chemicals | Huang P.,Nanjing Forestry University | And 9 more authors.
Chemistry and Industry of Forest Products | Year: 2015

In order to solve the key technical bottleneck for fuel ethanol production regarding the removal of inhibitors during co-fermentation of hexose and pentose, four main non-lignin constituents of corn stover, including cellulose, hemicellulose, hot water extractives and ethanol extractives, were prepared and then treated with 0.75% dilute sulfuric acid at 180℃ for 40 min, respectively. 60 g/L glucose and 30 g/L xylose were added to these prehydrolyzates. 5 various ethanolic fermentation medium were fermented to produce ethanol by Candida shehatae, respectively. Thus, the influences on ethanolic co-fermentation and the origination of the key inhibitors were comparatively studied. The results showed that the degradation products formed from 133 g/L corn stover inhibited microbial glycometabolism and co-fermentation totally. During pretreatment of corn stover by dilute sulfuric acid products degraded from four non-lignin constituents reduce the ethanol yield at different extents. Additionally, the products released from the cellulose degradation can completely inhibit the xylose fermentation. Glucose and xylose could be completely inhibited by the degradation products from hemicellulose, and these products perform lethal toxicity to Candida shehatae as well. The products generated from hot water extractives and ethanol extractives exert inhibition on cell growth and sugars utilization. The key inhibitors were mainly from degradation reaction of cellulose and hemicellulose during the pretreatment of corn by stover dilute sulfuric acid. Besides formic acid, acetic acid, levulinic acid, HMF and furfural in corn stover prehydrolyzates, other unknown degradation products also presented toxicity or synergistic inhibition on ethanolic co-fermentation of hexose and pentose. ©, 2015, The Editorial of «Chemistry and Industry of Forest Products». All right reserved.


Xu Y.,Nanjing Forestry University | Zheng Z.,Nanjing Forestry University | Xu Q.,Nanjing Forestry University | Yong Q.,Nanjing Forestry University | And 2 more authors.
Journal of Agricultural and Food Chemistry | Year: 2016

Inulooligosaccharides (IOS) represent an important class of oligosaccharides at industrial scale. An efficient conversion of inulin to IOS through endoinulinase from Aspergillus niger is presented. A 1482 bp codon optimized gene fragment encoding endoinulinase from A. niger DSM 2466 was cloned into pPIC9K vector and was transformed into Pichia pastoris KM71. Maximum activity of the recombinant endoinulinase, 858 U/mL, was obtained at 120 h of the high cell density fermentation process. The optimal conditions for inulin hydrolysis using the recombinant endoinulinase were investigated. IOS were harvested with a high concentration of 365.1 g/L and high yield up to 91.3%. IOS with different degrees of polymerization (DP, mainly DP 3-6) were distributed in the final reaction products. © 2016 American Chemical Society.

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