Kinetics of the Hot-Water Extraction of Paulownia Elongata Woodchips
About: This article is published in Journal of Bioprocess Engineering and Biorefinery.The article was published on 2013-03-01. It has received 12 citations till now. The article focuses on the topics: Paulownia elongata & Hot water extraction.
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TL;DR: Multi-scale structural studies of SB after sequential acid–base pretreatment and enzyme hydrolysis showed marked changes in hemicellulose and lignin removal at molecular level, and the cellulosic material showed high saccharification efficiency after enzymatic hydrolytic.
Abstract: Heavy usage of gasoline, burgeoning fuel prices, and environmental issues have paved the way for the exploration of cellulosic ethanol. Cellulosic ethanol production technologies are emerging and require continued technological advancements. One of the most challenging issues is the pretreatment of lignocellulosic biomass for the desired sugars yields after enzymatic hydrolysis. We hypothesized that consecutive dilute sulfuric acid-dilute sodium hydroxide pretreatment would overcome the native recalcitrance of sugarcane bagasse (SB) by enhancing cellulase accessibility of the embedded cellulosic microfibrils. SB hemicellulosic hydrolysate after concentration by vacuum evaporation and detoxification showed 30.89 g/l xylose along with other products (0.32 g/l glucose, 2.31 g/l arabinose, and 1.26 g/l acetic acid). The recovered cellulignin was subsequently delignified by sodium hydroxide mediated pretreatment. The acid–base pretreated material released 48.50 g/l total reducing sugars (0.91 g sugars/g cellulose amount in SB) after enzymatic hydrolysis. Ultra-structural mapping of acid–base pretreated and enzyme hydrolyzed SB by microscopic analysis (scanning electron microcopy (SEM), transmitted light microscopy (TLM), and spectroscopic analysis (X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Fourier transform near-infrared (FT-NIR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy) elucidated the molecular changes in hemicellulose, cellulose, and lignin components of bagasse. The detoxified hemicellulosic hydrolysate was fermented by Scheffersomyces shehatae (syn. Candida shehatae UFMG HM 52.2) and resulted in 9.11 g/l ethanol production (yield 0.38 g/g) after 48 hours of fermentation. Enzymatic hydrolysate when fermented by Saccharomyces cerevisiae 174 revealed 8.13 g/l ethanol (yield 0.22 g/g) after 72 hours of fermentation. Multi-scale structural studies of SB after sequential acid–base pretreatment and enzymatic hydrolysis showed marked changes in hemicellulose and lignin removal at molecular level. The cellulosic material showed high saccharification efficiency after enzymatic hydrolysis. Hemicellulosic and cellulosic hydrolysates revealed moderate ethanol production by S. shehatae and S. cerevisiae under batch fermentation conditions.
137 citations
TL;DR: In this paper, a synergetic approach is proposed to eliminate the waste generation in pretreatment and inserting a step to turn the otherwise waste into value-added product(s).
44 citations
TL;DR: The results indicated that despite the application of low cellulase dosage, high enzymatic hydrolysis efficiency substrate could be produced, and the sodium lignosulfonate which can be used for oilfields and concrete additives was obtained from the sodium sulfite–pretreated CCR.
Abstract: The effects of sodium sulfite pretreatment on the delignification rate, cellulose content, enzymatic hydrolysis efficiency, and glucose yield of corncob residues (CCR) were investigated. The optimum pretreatment conditions were as follows: 12% sodium sulfite, with a pH value of 7, a temperature of 160 °C, and a holding time of 20 min. Under the optimal conditions, the cellulose content in the pretreated residue was 85.17%, and sodium lignosulfonate with a sulfonation degree of 0.677 mmol/g was obtained in the waste liquids. A delignification rate of 77.45% was also achieved after the pretreatment. Enzymatic hydrolysis of pretreated CCR was carried out with cellulase (5 FPU/g substrate) and β-glucosidase (10 IU/g substrate) for 48 h. The untreated CCR were hydrolyzed using cellulase (20 FPU/g substrate) and β-glucosidase (10 IU/g substrate) for 48 h. The comparison results showed that sodium sulfite pretreatment improved the enzymatic hydrolysis efficiency and glucose yield, which increased by 28.80% and 20.10%, respectively. These results indicated that despite the application of low cellulase dosage, high enzymatic hydrolysis efficiency substrate could be produced, and the sodium lignosulfonate which can be used for oilfields and concrete additives was obtained from the sodium sulfite-pretreated CCR.
21 citations
Cites background from "Kinetics of the Hot-Water Extractio..."
...With extended temperature, the cellulose content and glucose yield of pretreatment CCR declined because a high temperature accelerated the degradation of cellulose (Cheng et al. 2011; Yan et al. 2013; Yan et al. 2016)....
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TL;DR: Investigation indicated that the composition of culture medium contributed to the enhanced R-3-HB production, and modifying the fermentation conditions that promotes the in vivo depolymerization and secretion to fermentation broth in wild type bacteria is a novel and promising approach to produce R-HAs.
Abstract: (R)-hydroxyalkanoic acids (R-HAs) are valuable building blocks for the synthesis of fine chemicals and biopolymers because of the chiral center and the two active functional groups. Hydroxyalkanoic acids fermentation can revolutionize the polyhydroxyalkanoic acids (PHA) production by increasing efficiency and enhancing product utility. Modifying the fermentation conditions that promotes the in vivo depolymerization and secretion to fermentation broth in wild type bacteria is a novel and promising approach to produce R-HAs. Wood extract hydrolysate (WEH) was found to be a suitable substrate for R-3-hydroxybutyric acid (R-3-HB) production by Burkholderia cepacia. Using Paulownia elongate WEH as a feedstock, the R-3-HB concentration in fermentation broth reached as high as 14.2 g/L after 3 days of batch fermentation and the highest concentration of 16.8 g/L was obtained at day 9. Further investigation indicated that the composition of culture medium contributed to the enhanced R-3-HB production.
17 citations
Cites methods from "Kinetics of the Hot-Water Extractio..."
...The extraction was conducted nominally at 160˚C for 2 h (Yan et al. 2013)....
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01 Jan 2016
TL;DR: It was observed that cold and, to a lesser extent, heat stress downregulated the expression of the putative cellulose synthase gene from Paulownia, which will help to understand cellulose deposition in plant cell wall under stressful conditions.
Abstract: Abstract Paulownia elongata is a short-rotation fast growing tree and is known for high biomass accumulation and carbon sequestration potential. Optimization of protocols for nucleic acid extraction, PCR, RT-PCR, and other molecular biology techniques are required for better understanding of cellulose synthesis and to assess the potential of Paulownia as a biofuel tree. The main objective of this work was to study a putative cellulose synthase amplicon expression under various environmental conditions and evaluate the potentials of Paulownia as a biofuel tree. Using cross-species PCR an amplicon representative of a putative cellulose synthase gene from Paulownia was identified. This 177-bp long DNA sequence was 46% similar with cellulose synthase genes from Arabidopsis as expected. Gene specific primers for this particular Paulownia cellulose synthase gene were designed and reverse transcription PCR was performed to confirm its transcription. We report an inexpensive cDNA dot-blot method to study expression of this gene under various environmental conditions. We observed that cold and, to a lesser extent, heat stress downregulated its expression. This information will help to understand cellulose deposition in plant cell wall under stressful conditions. To the best of our knowledge this is the first characterization of a cDNA sequence from Paulownia elongata.
13 citations
Cites background from "Kinetics of the Hot-Water Extractio..."
...Further, hot water extraction studies of Paulownia wood chips indicated that it could be a good substrate to release chemicals of high value [6]....
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