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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

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. Source

Li J.,Shanghai JiaoTong University | Li J.,Shanghai Environment and Energy Exchange Co. | Bin H.,Shanghai Environment and Energy Exchange Co. | Lin J.,Shanghai Environment and Energy Exchange Co. | And 3 more authors.
Bioresource Technology

Effects of white light-emitting diodes (LEDs) with different light intensities at photoperiod of 18:6h on Chlorella pyrenoidosa growth were investigated. The microalgae exhibited the highest growth rate 89.0mgL-1d-1 and growth efficiency 97.8mgL-1KWh-1 at 110 and 90μmolm-2s-1, respectively. Based on the discovery of this asynchronous phenomenon between growth rate and growth efficiency, influences of LEDs (red, blue and white) under capped daily energy consumption (0.80KWh d-1) with combinations of electric power (33.3, 44.4 and 66.6w) and photoperiod (24:0, 18:6 and 12:12h) were further investigated. The highest growth efficiency 106.4mgL-1KWh-1 and growth rate 85.1mgL-1d-1 were both obtained under white-33.3w-24h. Growth efficiency and growth rate were simultaneously improved 1.1 times through this method above. The order of growth efficiency under different LEDs were whitered. © 2016 Elsevier Ltd. Source

Wu H.,Shanghai JiaoTong University | Miao X.,Shanghai JiaoTong University | Miao X.,State Key Laboratory of Motor Vehicle Biofuel Technology
Bioresource Technology

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. Source

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

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. Source

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

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. Source

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