Wu H.,Shanghai JiaoTong University |
Miao X.,Shanghai JiaoTong University |
Miao X.,State Key Laboratory of Motor Vehicle Biofuel Technology
Bioresource Technology | Year: 2014
Biodiesel quality associated with biochemical components of Chlorella pyrenoidosa and Scenedesmus obliquus under different nitrate levels were investigated. The highest lipid contents of 54.5% for C. pyrenoidosa and 47.7% for S. obliquus were obtained in nitrate absence. Carbohydrate peaked at 0.3gL-1 with values of 40.7% for C. pyrenoidosa and 42.5% for S. obliquus. Protein content seemed species dependent, which decreased substantially to 11.2% in C. pyrenoidosa and 8.8% in S. obliquus under nitrate absence in present research. Better biodiesel quality (e.g. cetane number >58, iodine value <69) could be obtained from C. pyrenoidosa in nitrate absence and S. obliquus in 0.3gL-1, where the highest saturated fatty acids (39.5 for C. pyrenoidosa, 31.2 for S. obliquus) and the lowest unsaturated fatty acids (60.5 for C. pyrenoidosa, 68.8 for S. obliquus) were obtained. These results suggest that microalgae grown in the presence of nitrogen may limit biodiesel quality. © 2014 Elsevier Ltd.
Zhu W.,Zhengzhou University |
Chang C.,Zhengzhou University |
Ma C.,Shanghai JiaoTong University |
Du F.,State Key Laboratory of Motor Vehicle Biofuel Technology
Chinese Journal of Chemical Engineering | Year: 2014
The kinetics for production of ethyl levulinate from glucose in ethanol medium was investigated. The experiments were performed in various temperatures (433-473 K) and initial glucose concentrations (0.056-0.168 mol·L -1) with extremely low sulfuric acid as the catalyst. The results show that higher temperature can improve the conversion of glucose to ethyl levulinate, with higher yield of ethyl levulinate (44.79%, by mole) obtained at 473 K for 210 min. The kinetics follows a simplified first-order kinetic model. For the main and side reactions, the values of activation energy are 122.64 and 70.97 kJ·mol-1, and the reaction orders are 0.985 and 0.998, respectively. © 2014 Chemical Industry and Engineering Society of China (CIESC) and Chemical Industry Press (CIP).
Sun Z.,CAS Shanghai Institutes for Biological Sciences |
Chen Y.,CAS Shanghai Institutes for Biological Sciences |
Yang C.,CAS Shanghai Institutes for Biological Sciences |
Yang S.,CAS Shanghai Institutes for Biological Sciences |
And 4 more authors.
Molecular Microbiology | Year: 2015
Summary: d-Xylose is the most abundant fermentable pentose in nature and can serve as a carbon source for many bacterial species. Since d-xylose constitutes the major component of hemicellulose, its metabolism is important for lignocellulosic biomass utilization. Here, we report a six-protein module for d-xylose signaling, uptake and regulation in solvent-producing Clostridium beijerinckii. This module consists of a novel 'three-component system' (a putative periplasmic ABC transporter substrate-binding protein XylFII and a two-component system LytS/YesN) and an ABC-type d-xylose transporter XylFGH. Interestingly, we demonstrate that, although XylFII harbors a transmembrane domain, it is not involved in d-xylose transport. Instead, XylFII acts as a signal sensor to assist the response of LytS/YesN to extracellular d-xylose, thus enabling LytS/YesN to directly activate the transcription of the adjacent xylFGH genes and thereby promote the uptake of d-xylose. To our knowledge, XylFII is a novel single transmembrane sensor that assists two-component system to respond to extracellular sugar molecules. Also of significance, this 'three-component system' is widely distributed in Firmicutes, indicating that it may play a broad role in this bacterial phylum. The results reported here provide new insights into the regulatory mechanism of d-xylose sensing and transport in bacteria. © 2014 John Wiley & Sons Ltd.
Wang P.-M.,Zhejiang University |
Zheng D.-Q.,Zhejiang University |
Chi X.-Q.,Xiamen University |
Li O.,Zhejiang University |
And 7 more authors.
Bioresource Technology | Year: 2014
The protective effect and the mechanisms of trehalose accumulation in industrial Saccharomyces cerevisiae strains were investigated during ethanol fermentation. The engineered strains with more intercellular trehalose achieved significantly higher fermentation rates and ethanol yields than their wild strain ZS during very high gravity (VHG) fermentation, while their performances were not different during regular fermentation. The VHG fermentation performances of these strains were consistent with their growth capacity under osmotic stress and ethanol stress, the key stress factors during VHG fermentation. These results suggest that trehalose accumulation is more important for VHG fermentation of industrial yeast strains than regular one. The differences in membrane integrity and antioxidative capacity of these strains indicated the possible mechanisms of trehalose as a protectant under VHG condition. Therefore, trehalose metabolic engineering may be a useful strategy for improving the VHG fermentation performance of industrial yeast strains. © 2013.
Wu Y.,CAS Shanghai Institutes for Biological Sciences |
Wu Y.,University of Chinese Academy of Sciences |
Yang Y.,CAS Shanghai Institutes for Biological Sciences |
Yang Y.,University of Chinese Academy of Sciences |
And 10 more authors.
Metabolic Engineering | Year: 2015
Efficient cofermentation of hexose and pentose sugars is essential for ABE (. Acetone, Butanol and Ethanol) solvents production from lignocellulosic hydrolysates by Clostridium acetobutylicum, an important industrial microorganism. However, utilization of xylose, the predominant pentose present in lignocellulosic feedstocks, by this anaerobe is limited by CCR (. Carbon Catabolite Repression) that is mediated by the catabolite control protein A (CcpA). Here, we reported a novel engineering strategy based on CcpA molecular modulation to overcome the defect. Through CcpA mutagenesis and screening, an amino acid residue, valine 302, was shown to be essential for CcpA-dependent CCR in C. acetobutylicum. When this residue was replaced by asparagine (V302N mutation), CCR could be alleviated and a greatly improved xylose utilization was realized. Transcriptional and DNA binding analysis was then used to elucidate the underlying molecular mechanism. Furthermore, the sol genes (. ctfA, ctfB and adhE1) were overexpressed, upon the V302N mutation, to accelerate sugar consumption and solvents formation. The resulting strain (824ccpA-V302N-sol) was capable of using over 90% of the total xylose within 72. h when fermenting a mixture of glucose and xylose (30. g/L glucose and 15. g/L xylose), which was much higher than that (30%) of the control strain 824ccpA-ccpA(C). This is the first report that offered an optimized C. acetobutylicum CcpA with alleviated repression on xylose metabolism, yielding a valuable platform host toward ABE solvents production from lignocellulosic biomass. © 2015 International Metabolic Engineering Society.
Zhang J.,Beijing University of Chemical Technology |
Zhang J.,State Key Laboratory of Motor Vehicle Biofuel Technology |
Song Y.,Beijing University of Chemical Technology |
Wang B.,Beijing University of Chemical Technology |
And 2 more authors.
Renewable Energy | Year: 2016
The second generation biomass to bio-ethanol production is of growing interest. Energy crop were becoming important for second generation biomass to bio-ethanol production for their growth advantages. Hybrid Pennisetum as a new hybrid energy crop was selected as a model to compare with corn stalk. As pre-treatment methods, steam explosion and its combined action with dilute sulfuric acid, bisulfite, and mixed dilute acid and bisulfite were selected. The enzymatic hydrolysis demonstrated that the cellulose conversion is a strong function of the pre-treatment method applied, with corn stalk providing slightly better results. With dilute acid steam explosion (DA-SE), conversions were 67.6% and 54.5% for corn stalk and pennisetum, respectively. This can be attributed to the higher Cr. I of pennisetum (65.03%) than of corn stalk (54.05%). The cell lumen of pretreated pennisetum was smaller than for corn stalk as shown in SEM photos, meaning there was a substantially higher enzyme accessible surface and porosity in pennisetum, thus responsible for the higher cellulase adsorption of pretreated pennisetum. DA-SE was the most effective pre-treatment method, but the inhibitors' concentration was higher than in other methods. Combined dilute acid and bisulfite can moderately remove hemicelluloses and lignin. Cr. I values, lignin content, accessible surface and porosity were supplied the energy crop evaluation standards for bio-ethanol production. © 2015 Elsevier Ltd.
PubMed | State Key Laboratory of Motor Vehicle Biofuel Technology and Beijing University of Chemical Technology
Type: | Journal: Bioresource technology | Year: 2015
Floating tests were conducted in anaerobic digestion with different OLR of corn stover to investigate formation of floating layers and to find proper agitation interval for preventing floating layer formation. Floating layers were formed in the early stage of no-agitation period. The daily biogas production was decreased by 81.87-87.90% in digesters with no agitation and feeding compared with digesters having agitation. Reduction of biogas production was mainly attributed to poor contact of substrate-microorganisms. Agitation intervals of 10 h, 6 h, and 2 h were found to be proper for eliminating floating layer at OLR of 1.44, 1.78 and 2.11 g(TS) L(-1) d(-1), respectively. The proper agitation interval was further validated by anaerobic experiments. It showed that proper agitation interval could not only prevent floating layer formation and achieve high biogas production but also increase energy efficiency of anaerobic digestion. The finding is useful for operating anaerobic digester with corn stover in a cost-effective way.
Chen J.,Nanjing University of Technology |
Zhang Y.,Zhejiang University |
Wang Y.,Zhejiang University |
Ji X.,Zhejiang University |
And 4 more authors.
Bioresource Technology | Year: 2013
In this study, vacuum membrane distillation (VMD) was used to remove two prototypical fermentation inhibitors (acetic acid and furfural) from lignocellulose hydrolyzates. The effect of operating parameters, such as feed temperature and feed velocity, on the removal efficiencies of inhibitors was investigated. Under optimal conditions, more than 98% of furfural could be removed by VMD. However, the removal efficiency of acetic acid was considerably lower. After furfural and acetic acid were selectively removed from hydrolyzates by VMD, ethanol production efficiency increased by 17.8% compared to original hydrolyzates. © 2013 Elsevier Ltd.
Zhang X.-Y.,Enterprise Group |
Zhang X.-Y.,State Key Laboratory of Motor Vehicle Biofuel Technology
Advances in Climate Change Research | Year: 2016
Biomass energy would become the most potential renewable energies, for whether wind power or photovoltaic, would be restricted by the nature thus cannot provide stable power, while biomass energy is the only renewable energy that can be used in the form of gas, liquid or solid stage, it could replace the fossil energy, lead a positive influence on the control of the greenhouse gases. Across the globe, the biomass produced through photosynthesis is about 200 Gt, or 99 Gtce per year. If 10% of the biomass is utilized, more than 4 Gt of fuel ethanol and other bioenergy products can be produced, equivalent to 4.13 Gt of petroleum consumed by the world in 2014. Therefore, bioenergy can be a feasible alternative to fossil energy. © 2016 National Climate Center (China Meteorological Administration)
Gu H.,East China University of Science and Technology |
Zhang J.,East China University of Science and Technology |
Bao J.,East China University of Science and Technology |
Bao J.,State Key Laboratory of Motor Vehicle Biofuel Technology
Bioresource Technology | Year: 2014
Industrial waste corncob residues (CCR) are rich in cellulose and can be hydrolyzed directly without pretreatment. However, a poor fermentation performance was frequently observed in the simultaneous saccharification and ethanol fermentation (SSF) of CCR, although the furans and organic acid inhibitors were very low. In this study, the high level of water-insoluble phenolic compounds such as 2-furoic acid, ferulic acid, p-coumaric acid, guaiacol, and p-hydroxybenzoic acid were detected in CCR and inhibited the growth and metabolism of Saccharomyces cerevisiae DQ1. An evolutionary adaptation strategy was developed by culturing the S. cerevisiae DQ1 strain in a series of media with the gradual increase of CCR hydrolysate. The high ethanol concentration (62.68. g/L) and the yield (55.7%) were achieved in the SSF of CCR using the adapted S. cerevisiae DQ1. The results provided a practical method for improving performance of simultaneous saccharification and ethanol production from CCR. © 2014 Elsevier Ltd.