Jiangsu Key Laboratory of Biomass Based Green Fuels and Chemicals

Nanjing, China

Jiangsu Key Laboratory of Biomass Based Green Fuels and Chemicals

Nanjing, China

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Ouyang J.,Jiangsu Key Laboratory of Biomass Based Green Fuels and Chemicals | Liu B.,Nanjing Forestry University | Zhang M.,Nanjing Forestry University | Zheng Z.,Nanjing Forestry University | Yu H.,Nanjing Forestry University
Bioresource Technology | Year: 2013

The high costs of enzymatic hydrolysis along with the high enzyme dosage are often considered as the major bottlenecks in lignocellulosic bioconversion. This study investigated the hydrolysis efficiency, cellulase adsorption and enzyme recycling during the hydrolysis of bagasse sulfite pulp (BSP). After 48. h of hydrolysis, more than 70% of the cellulose was hydrolyzed, while the protein concentration and cellulase activity in solution remained 31% and 17% of the initial value, respectively. The cellulase adsorption on the fresh BSP was better fitted by a Sips model, suggesting the occurrence of a multilayer adsorption at low cellulase concentration and monolayer adsorption at high concentration on the BSP surfaces. Desorption profile studies showed that the optimum desorption condition was at pH 4.8 and 40. °C. Moreover, considering the limited ability to desorption, directly empolying the bound enzyme with residual substrate is more effective method to recover cellulase during the hydrolysis of BSP. © 2013 .


Pei J.,Nanjing Forestry University | Pei J.,Jiangsu Key Laboratory of Biomass Based Green Fuels and Chemicals | Pang Q.,Nanjing Forestry University | Pang Q.,Jiangsu Key Laboratory of Biomass Based Green Fuels and Chemicals | And 6 more authors.
Biotechnology for Biofuels | Year: 2012

Background: -Glucosidase is an important component of the cellulase enzyme system. It does not only participate in cellulose degradation, it also plays an important role in hydrolyzing cellulose to fermentable glucose by relieving the inhibition of exoglucanase and endoglucanase from cellobiose. Therefore, the glucose-tolerant β-glucosidase with high specific activity for cellobiose might be a potent candidate for industrial applications. Results: The β-glucosidase gene bgl that encodes a 443-amino-acid protein was cloned and over-expressed from Thermoanaerobacterium thermosaccharolyticum DSM 571 in Escherichia coli. The phylogenetic trees of β-glucosidases were constructed using Neighbor-Joining (NJ) and Maximum-Parsimony (MP) methods. The phylogeny and amino acid analysis indicated that the BGL was a novel β-glucosidase. By replacing the rare codons for the N-terminal amino acids of the target protein, the expression level of bgl was increased from 6.6 to 11.2 U/mg in LB medium. Recombinant BGL was purified by heat treatment followed by Ni-NTA affinity. The optimal activity was at pH 6.4 and 70°C. The purified enzyme was stable over pH range of 5.2-7.6 and had a 1 h half life at 68°C. The activity of BGL was significantly enhanced by Fe 2+ and Mn 2+. The V max of 64 U/mg and 120 U/mg were found for p-nitrophenyl - D-glucopyranoside (K m value of 0.62mM) and cellobiose (K m value of 7.9mM), respectively. It displayed high tolerance to glucose and cellobiose. The K cat for cellobiose was 67.7s -1 at 60°C and pH 6.4, when the concentration of cellobiose was 290mM. It was activated by glucose at concentrations lower that 200mM. With glucose further increasing, the enzyme activity of BGL was gradually inhibited, but remained 50% of the original value in even as high as 600mM glucose. Conclusions: The article provides a useful novel β-glucosidase which displayed favorable properties: high glucose and cellobiose tolerance, independence of metal ions, and high hydrolysis activity on cellobiose. © 2012 Pei et al; licensee BioMed Central Ltd.


Xu X.,Nanjing Forestry University | Xu X.,Jiangsu Key Laboratory of Biomass based Green Fuels and Chemicals | Yang Y.-Q.,Nanjing Forestry University | Xing Y.-Y.,Nanjing Forestry University | And 5 more authors.
Carbohydrate Polymers | Year: 2013

Novel polyvinyl alcohol (PVA) blend membranes containing cellulose nanocrystals (CNs) and silver nanoparticles (AgNPs) were prepared via a simple method. CNs were prepared by sulfuric acid treatment of microcrystalline cellulose. AgNO3 aqueous solution mixed with the CNs aqueous suspension and was reduced by NaBH4 at room temperature. Purified CNs/AgNPs nanocomposites as functional fillers mixed with polyvinyl alcohol to prepare blend membrane. The morphology, mechanical properties, and antibacterial activities of PVA/CNs/AgNPs composite films were investigated. The PVA/CNs/AgNPs composite films were stable and homogeneous. The tensile strength of PVA was increased from 57.02 MPa to 81.21 MPa when filled with CNs/AgNPs. Antibacterial ratio of PVA/CNs/AgNPs composite against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus was 96.9% and 88.2%, respectively. The CNs/AgNPs nanocomposites could be applied as bi-functional nanofillers within PVA to improve the mechanical properties and antibacterial activities. © 2013 Elsevier Ltd. All rights reserved.


Li Z.,Nanjing Forestry University | Li Z.,Jiangsu Key Laboratory of Biomass Based Green Fuels and Chemicals | Li X.,Nanjing Forestry University | Li X.,Jiangsu Key Laboratory of Biomass Based Green Fuels and Chemicals | And 5 more authors.
Bioresource Technology | Year: 2011

The Rhizopus oryzae lipase containing prosequence was expressed in Pichia pastoris. Recombinant lipase subunit showed a molecular mass of 32kDa. The maximum activity of recombinant lipase obtained from Mut s recombinant was 90IU/ml. The enzyme was stable in broad ranges of temperatures and pH, with the optimal temperature at 35°C and pH 7.0. The crude recombinant R. oryzae lipase can be directly used for the transesterification of plant oils at high-water content of 60-100% (w/w) based on oil weight. The addition of 80% water to the transesterification systems resulted in the yield of methyl ester of 95%, 94% and 92% after 72h using soybean oil, Jatropha curcas seed raw oil and Pistacia chinensis seed raw oil as raw material, respectively. These results indicate that the recombinant lipase is an effective biocatalyst for enzymatic biodiesel production. © 2011 Elsevier Ltd.


Wang X.,Nanjing Forestry University | Xu Y.,Nanjing Forestry University | Xu Y.,Jiangsu Key Laboratory of Biomass based Green Fuels and Chemicals | Lian Z.,Nanjing Forestry University | And 2 more authors.
Journal of Wood Chemistry and Technology | Year: 2014

Interest in biomass biorefineries and especially their aldonic acid products has been growing in recent years. However, the analytical methods for aldonic acids have only rarely been explored. In this study, a simple one-step method was developed using high-performance anion-exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD).With this method, five wood monosaccharides and their corresponding aldonic acids, including arabinose, galactose, glucose, xylose, mannose, arabonic acid, galactonic acid, gluconic acid, xylonic acid, and mannonic acid, were simultaneously separated and quantitatively determined. The separation was performed on a CarboPac™ PA-10 column (250 mm × 2 mm) with a gradient elution using NaOH solution as the mobile phase. The calibration curves showed good linearity (R2 ≥ 0.9993) for the five monosaccharides and the corresponding aldonic acids in the range of 0.1 to 10.0 mg/L. The spiked recoveries of the 10 components ranged from 93.92% to 104.15%, with relative standard deviations (RSDs) (n = 3) of 0.49% to 3.95%. The established method was applied successfully to determine the quantitative variation of monosaccharide and aldonic acid contents in products from a biomass biorefinery. Copyright © Taylor & Francis Group, LLC.


Zhao L.,Nanjing Forestry University | Zhao L.,Jiangsu Key Laboratory of Biomass Based Green Fuels and Chemicals | Xie J.,Nanjing Forestry University | Xie J.,Jiangsu Key Laboratory of Biomass Based Green Fuels and Chemicals | And 4 more authors.
Journal of Molecular Catalysis B: Enzymatic | Year: 2013

The β-glucosidase gene Tt-bgl from Thermotoga thermarum DSM 5069T was cloned and overexpressed in Escherichia coli. A simple strategy, induction at 37 °C with no IPTG, was explored to reduce the inclusion bodies, by which the activity of Tt-BGL was 13 U/mL in LB medium. Recombinant Tt-BGL was purified by heat treatment followed by Ni.NTA affinity. The optimal activity was at pH 4.8 and 90 °C. The activity of Tt-BGL was significantly enhanced by methanol and Al3+. The enzyme was stable over pH range of 4.4.8.0, and had a 2-h half life at 90 °C. The Vmax for p-nitrophenyl-β-d- glucopyranoside and ginsenoside Rb1 was 142 U/mg and 107 U/mg, while the K m was 0.59 mM and 0.15 mM, respectively. The activity of the enzyme was not inhibited by ginsenoside Rb1 (36 g/L). It was activated by glucose at concentrations lower that 400 mM. With glucose further increasing, the activity of Tt-BGL was gradually inhibited, but remained 50% of the original value in even as high as 1500 mM glucose. Under the optimal conditions, Tt-BGL transformed ginsenoside Rb1 (36 g/L) to Rd by 95% in 1 h. © 2013 Elsevier B.V.


Li X.,Nanjing Forestry University | He X.-Y.,Nanjing Forestry University | Li Z.-L.,Nanjing Forestry University | Wang Y.-D.,Nanjing Forestry University | And 4 more authors.
Fuel | Year: 2012

Biodiesel fuel from renewable non-edible woody plant oils has recently attracted more attention due to its environmental benefits and the reduced costs of raw materials. This study investigated the enzymatic transesterification of Pistacia chinensis bge seed oil (PCO) with methanol. The recombinant Rhizopus oryzae lipases (ROL) immobilized on macroporous resin and anion exchange resin, named as MI-ROL and AI-ROL, respectively, were used as biocatalysts. The transesterification reaction catalyzed by the immobilized lipase was investigated in a solvent-free system. The highest biodiesel yields of 92% and 94% were achieved under the optimum conditions (enzyme dosage 25 IU AI-ROL/g PCO or 7 IUMI-ROL/g PCO, methanol to oil molar ratio 5:1, water content 20% by weight of oil, temperature 37 °C, and reaction time 60 h). There was no obvious loss in the yield of biodiesel after being consecutively used for five cycles in the transesterification reactions using AI-ROL, while the yield of biodiesel remained above 60% after the MI-ROL was repeatedly used for four cycles. © 2011 Elsevier Ltd. All rights reserved.


Li X.,University of Georgia | Li X.,Nanjing Forestry University | Li X.,Jiangsu Key Laboratory of Biomass Based Green Fuels and Chemicals | Huang Y.,University of Georgia | Whitman W.B.,University of Georgia
Antonie van Leeuwenhoek, International Journal of General and Molecular Microbiology | Year: 2015

In the original proposal of Wayne et al. (Int J Syst Bacteriol 37:463–464, 1987), two measures of genetic relatedness were proposed to set the boundary for prokaryotic species. The first was the change in the melting temperature (ΔTm) of heteroduplex DNA and the second was the extent of DNA–DNA hybridization (DDH). While this approach was justified given the experimental error inherent in these methods, genomic sequencing has the potential to measure both parameters with great precision. The average nucleotide identity (ANIb), a surrogate for the ΔTm, and the calculated DDH (cDDH) were determined from the complete genomes of representatives of 17 genera of prokaryotes. When the ANIb was >75 %, the ratio (100-cDDH)/(100-ANIb) was 3.69 ± 0.93 (± SD) and varied from about 2.35 to 4.59 between genera. The differences among genera was highly significant (p < 0.001) but not correlated with specific phylogenetic or physiological groups. Moreover, the ANIm was a poor measure of ANIb when ANIb was <75 %. Because the ANIb and cDDH provide different measures of relatedness, it is no longer appropiate to consider both when delineating species. For these reasons, measures of relatedness based upon sequence identity should be used for delineating species in the future. © 2014, Springer International Publishing Switzerland.


Du L.,Nanjing Forestry University | Yang S.,Nanjing Forestry University | Xu L.,Nanjing Forestry University | Xu L.,Jiangsu Key Laboratory of Biomass Based Green Fuels and Chemicals | And 2 more authors.
CrystEngComm | Year: 2014

A microporous acylamide-functionalized metal-organic framework with a kgm-pillared structure, [Cu(NAIP2-)]n, has been designed by self-assembling [Cu2(COO)4] paddlewheel SBUs and a novel trigonal heterofunctional ligand with a linking acylamide group. [Cu(NAIP2-)]n exhibits a moderate BET surface area of 1060 m2 g-1, high CO2 uptake (4.5 wt% at 0.15 bar and 298 K; 201.8 cm3 g-1 at 20 bar and 298 K) and high selectivity for CO2 over CH4 (8.34) and N2 (38.3) at 273 K. © the Partner Organisations 2014.


Wang X.,Nanjing Forestry University | Xu Y.,Nanjing Forestry University | Xu Y.,Jiangsu Key Laboratory of Biomass based Green Fuels and Chemicals | Fan L.,Nanjing Forestry University | And 2 more authors.
BioResources | Year: 2012

A method for simultaneous separation and quantitative determination of arabinose, galactose, glucose, xylose, xylonic acid, gluconic acid, galacturonic acid, and glucuronic acid was developed by using high performance anion-exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD). The separation was performed on a CarboPac™ PA-10 column (250 mm × 2 mm) with a various gradient elution of NaOH-NaOAc solution as the mobile phase. The calibration curves showed good linearity (R2 ≥ 0.9993) for the monosaccharides, uronic acids, and aldonic acids in the range of 0.1 to 12.5 mg/L. The detection limits (LODs) and the quantification limits (LOQs) were 4.91 to 18.75 μg/L and 16.36 to 62.50 μg/L, respectively. Relative standard deviations (RSDs) of the retention times and peak areas for the seven consecutive determinations of an unknown amount of mixture were 0.15% to 0.44% and 0.22% to 2.31%, respectively. The established method was used to separate and determine four monosaccharides, two uronic acids, and two aldonic acids in the prehydrolysate from dilute acid steam-exploded corn stover within 21 min. The spiked recoveries of monosaccharides, uronic acids, and aldonic acids ranged from 91.25% to 108.81%, with RSDs (n=3) of 0.04% ~ 6.07%. This method was applied to evaluate the quantitative variation of sugar and sugar acid content in biomass prehydrolysates.

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