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Effects of Colloid Milling and Hot-Water Pretreatment on Physical Properties and Enzymatic Digestibility of Oak Wood. ENERGIES 2022. [DOI: 10.3390/en15062210] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
A two-step process using colloid milling (CM) and hot water (HW) treatment was evaluated for its ability to improve xylose recovery and the enzymatic digestibility of oak wood. In the first step, CM pretreatment was applied at a milling (feeding) speed of 100 mL/min with four different milling times (3, 6, 9, and 12 h), and the enzymatic digestibility and physical properties of each substrate were measured. In the second-step, the HW pretreatment was applied to enhance the enzymatic digestibility and xylan recovery at various reaction severities (Log R0) from 2.07 to 4.43 using 12 h colloid-milled (CM-treated) oak wood. Compared with untreated oak wood, CM not only significantly disrupted the structure of oak wood but also increased its Brunauer–Emmett–Teller surface area (42-fold) and pore volume (28-fold). The crystallinity of two-step-treated oak wood was decreased to 34.8, while the enzymatic digestibility of 12 h CM-treated oak wood was increased to 58.1% at enzyme loading of 30 filter paper units (FPU)/g glucan for 96 h. After HW treatment of CM-treated oak wood at Log R0 = 3.83, 80.7% of xylan recovery yield and 91.1% of enzymatic digestibility (with 15 FPU/g glucan at 96 h) was obtained, which was 84.2% higher than the enzymatic digestibility of untreated oak wood (6.9%).
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Ruchala J, Sibirny AA. Pentose metabolism and conversion to biofuels and high-value chemicals in yeasts. FEMS Microbiol Rev 2020; 45:6034013. [PMID: 33316044 DOI: 10.1093/femsre/fuaa069] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 12/09/2020] [Indexed: 12/15/2022] Open
Abstract
Pentose sugars are widespread in nature and two of them, D-xylose and L-arabinose belong to the most abundant sugars being the second and third by abundance sugars in dry plant biomass (lignocellulose) and in general on planet. Therefore, it is not surprising that metabolism and bioconversion of these pentoses attract much attention. Several different pathways of D-xylose and L-arabinose catabolism in bacteria and yeasts are known. There are even more common and really ubiquitous though not so abundant pentoses, D-ribose and 2-deoxy-D-ribose, the constituents of all living cells. Thus, ribose metabolism is example of endogenous metabolism whereas metabolism of other pentoses, including xylose and L-arabinose, represents examples of the metabolism of foreign exogenous compounds which normally are not constituents of yeast cells. As a rule, pentose degradation by the wild-type strains of microorganisms does not lead to accumulation of high amounts of valuable substances; however, productive strains have been obtained by random selection and metabolic engineering. There are numerous reviews on xylose and (less) L-arabinose metabolism and conversion to high value substances; however, they mostly are devoted to bacteria or the yeast Saccharomyces cerevisiae. This review is devoted to reviewing pentose metabolism and bioconversion mostly in non-conventional yeasts, which naturally metabolize xylose. Pentose metabolism in the recombinant strains of S. cerevisiae is also considered for comparison. The available data on ribose, xylose, L-arabinose transport, metabolism, regulation of these processes, interaction with glucose catabolism and construction of the productive strains of high-value chemicals or pentose (ribose) itself are described. In addition, genome studies of the natural xylose metabolizing yeasts and available tools for their molecular research are reviewed. Metabolism of other pentoses (2-deoxyribose, D-arabinose, lyxose) is briefly reviewed.
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Affiliation(s)
- Justyna Ruchala
- Department of Microbiology and Molecular Genetics, University of Rzeszow, Zelwerowicza 4, Rzeszow 35-601, Poland.,Department of Molecular Genetics and Biotechnology, Institute of Cell Biology NAS of Ukraine, Drahomanov Street, 14/16, Lviv 79005, Ukraine
| | - Andriy A Sibirny
- Department of Microbiology and Molecular Genetics, University of Rzeszow, Zelwerowicza 4, Rzeszow 35-601, Poland.,Department of Molecular Genetics and Biotechnology, Institute of Cell Biology NAS of Ukraine, Drahomanov Street, 14/16, Lviv 79005, Ukraine
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Zhao C, Shao Q, Chundawat SPS. Recent advances on ammonia-based pretreatments of lignocellulosic biomass. BIORESOURCE TECHNOLOGY 2020; 298:122446. [PMID: 31791921 DOI: 10.1016/j.biortech.2019.122446] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 11/15/2019] [Accepted: 11/16/2019] [Indexed: 05/06/2023]
Abstract
Ammonia-based pretreatments have been extensively studied in the last decade as one of the leading pretreatment technologies for lignocellulose biorefining. Here, we discuss the key features and compare performances of several leading ammonia-based pretreatments (e.g., soaking in aqueous ammonia or SAA, ammonia recycled percolation or ARP, ammonia fiber expansion or AFEX, and extractive ammonia or EA). We provide detailed insight into the distinct physicochemical mechanisms employed during ammonia-based pretreatments and its impact on downstream bioprocesses (e.g., enzymatic saccharification); such as modification of cellulose crystallinity, lignin/hemicellulose structure, and other ultrastructural changes such as cell wall porosity. Lastly, a brief overview of process technoeconomics and environmental impacts are discussed, along with recommendations for future areas of research on ammonia-based pretreatments.
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Affiliation(s)
- Chao Zhao
- National Engineering Research Center for Wood-based Resource Utilization, School of Engineering, Zhejiang A&F University, Linan, Zhejiang 311300, People's Republic of China
| | - Qianjun Shao
- Faculty of Mechanical Engineering & Mechanics, Ningbo University, Ningbo, Zhejiang 315211, People's Republic of China
| | - Shishir P S Chundawat
- Department of Chemical & Biochemical Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA.
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Kim DH, Park HM, Jung YH, Sukyai P, Kim KH. Pretreatment and enzymatic saccharification of oak at high solids loadings to obtain high titers and high yields of sugars. BIORESOURCE TECHNOLOGY 2019; 284:391-397. [PMID: 30959376 DOI: 10.1016/j.biortech.2019.03.134] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 03/26/2019] [Accepted: 03/27/2019] [Indexed: 05/28/2023]
Abstract
Production of high-titer sugar from lignocellulose is important in terms of process economics of bio-based product industry. In this study, to obtain high titers and yields of sugars, we combined pretreatment and saccharification steps, both at high solids loadings. First, pretreatment of oak was optimized at a 30% (w/w) solids loading. The whole slurry of the pretreated oak was subjected to a fed-batch saccharification step at the final solids loading of 30%, to minimize loss of fermentable sugars and simplify the processes. As a result, high-titer sugars (157.5 g/L) consisting of 120.2 g/L of glucose and 37.3 g/L of xylose were obtained at 75.9% and 58.6%, respectively, of theoretical maximum yields, based on the initial glucan and xylan contents. Thus, through proper optimization processes of oak, the combination of pretreatment and saccharification at high solids loadings was effective in obtaining both high titers and high yields of sugars from lignocellulose.
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Affiliation(s)
- Dong Hyun Kim
- Department of Biotechnology, Graduate School, Korea University, Seoul 02841, South Korea
| | - Hyun Min Park
- Department of Biotechnology, Graduate School, Korea University, Seoul 02841, South Korea
| | - Young Hoon Jung
- School of Food Science and Biotechnology, Kyungpook National University, Daegu 41566, South Korea
| | - Prakit Sukyai
- Biotechnology of Biopolymers and Bioactive Compounds Special Research Unit, Department of Biotechnology, Faculty of Agro-Industry, Kasetsart University, Chatuchak, Bangkok 10900, Thailand
| | - Kyoung Heon Kim
- Department of Biotechnology, Graduate School, Korea University, Seoul 02841, South Korea.
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Dong M, Wang S, Xu F, Wang J, Yang N, Li Q, Chen J, Li W. Pretreatment of sweet sorghum straw and its enzymatic digestion: insight into the structural changes and visualization of hydrolysis process. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:276. [PMID: 31768194 PMCID: PMC6874820 DOI: 10.1186/s13068-019-1613-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Accepted: 11/10/2019] [Indexed: 05/03/2023]
Abstract
BACKGROUND The efficient utilization of lignocellulosic biomass for biofuel production has received increasing attention. Previous studies have investigated the pretreatment process of biomass, but the detailed enzymatic hydrolysis process of pretreated biomass remains largely unclear. Thus, this study investigated the pretreatment efficiency of dilute alkali, acid, hydrogen peroxide and its ultimate effects on enzymatic hydrolysis. Furthermore, to better understand the enzymatic digestion process of alkali-pretreated sweet sorghum straw (SSS), multimodal microscopy techniques were used to visualize the enzymatic hydrolysis process. RESULT After pretreatment with alkali, an enzymatic hydrolysis efficiency of 86.44% was obtained, which increased by 99.54% compared to the untreated straw (43.23%). The FTIR, XRD and SEM characterization revealed a sequence of microstructural changes occurring in plant cell walls after pretreatment, including the destruction of lignin-polysaccharide interactions, the increase of porosity and crystallinity, and reduction of recalcitrance. During the course of hydrolysis, the cellulase dissolved the cell walls in the same manner and the digestion firstly occurred from the middle of cell walls and then toward the cell wall corners. The CLSM coupled with fluorescent labeling demonstrated that the sclerenchyma cells and vascular bundles in natural SSS were highly lignified, which caused the nonproductive bindings of cellulase on lignin. However, the efficient delignification significantly increased the accessibility and digestibility of cellulase to biomass, thereby improving the saccharification efficiency. CONCLUSION This work will be helpful in investigating the biomass pretreatment and its structural characterization. In addition, the visualization results of the enzymatic hydrolysis process of pretreated lignocellulose could be used for guidance to explore the lignocellulosic biomass processing and large-scale biofuel production.
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Affiliation(s)
- Miaoyin Dong
- Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Rd., Lanzhou, 730000 Gansu People’s Republic of China
- College of Life Sciences, University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049 People’s Republic of China
| | - Shuyang Wang
- Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Rd., Lanzhou, 730000 Gansu People’s Republic of China
- Institute of Biology, Gansu Academy of Sciences, 197 Dingxi South Rd., Lanzhou, 730000 Gansu People’s Republic of China
- College of Life Sciences, University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049 People’s Republic of China
| | - Fuqiang Xu
- Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Rd., Lanzhou, 730000 Gansu People’s Republic of China
- College of Life Sciences, University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049 People’s Republic of China
| | - Junkai Wang
- College of Physics and Electronic Engineering, Northwest Normal University, Anning Rd., Lanzhou, 730000 Gansu People’s Republic of China
| | - Ning Yang
- College of Life Sciences, Northwest Normal University, Anning Rd., Lanzhou, 730000 Gansu People’s Republic of China
| | - Qiaoqiao Li
- Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Rd., Lanzhou, 730000 Gansu People’s Republic of China
- College of Life Sciences, University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049 People’s Republic of China
| | - Jihong Chen
- Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Rd., Lanzhou, 730000 Gansu People’s Republic of China
- College of Life Sciences, University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049 People’s Republic of China
| | - Wenjian Li
- Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Rd., Lanzhou, 730000 Gansu People’s Republic of China
- College of Life Sciences, University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049 People’s Republic of China
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Wang Q, Hu J, Shen F, Mei Z, Yang G, Zhang Y, Hu Y, Zhang J, Deng S. Pretreating wheat straw by the concentrated phosphoric acid plus hydrogen peroxide (PHP): Investigations on pretreatment conditions and structure changes. BIORESOURCE TECHNOLOGY 2016; 199:245-257. [PMID: 26264398 DOI: 10.1016/j.biortech.2015.07.112] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 07/27/2015] [Accepted: 07/28/2015] [Indexed: 05/25/2023]
Abstract
Wheat straw was pretreated by PHP (the concentrated H3PO4 plus H2O2) to clarify effects of temperature, time and H3PO4 proportion on hemicellulose removal, delignification, cellulose recovery and enzymatic digestibility. Overall, hemicellulose removal was intensified by PHP comparing to the concentrated H3PO4. Moreover, efficient delignification specially happened in PHP pretreatment. Hemicellulose removal and delignification by PHP positively responded to temperature and time. Increasing H3PO4 proportion in PHP can promote hemicellulose removal, however, decrease the delignification. Maximum hemicellulose removal and delignification were achieved at 100% and 83.7% by PHP. Enzymatic digestibility of PHP-pretreated wheat straw was greatly improved by increasing temperature, time and H3PO4 proportion, and complete hydrolysis can be achieved consequently. As temperature of 30-40°C, time of 2.0 h and H3PO4 proportion of 60% were employed, more than 92% cellulose was retained in the pretreated wheat straw, and 29.1-32.6g glucose can be harvested from 100g wheat straw.
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Affiliation(s)
- Qing Wang
- Institute of Ecological and Environmental Sciences, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China
| | - Jinguang Hu
- Forest Products Biotechnology, Department of Wood Science, The University of British Columbia, Vancouver V6T 1Z4, BC, Canada
| | - Fei Shen
- Institute of Ecological and Environmental Sciences, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China.
| | - Zili Mei
- Biogas Institute of Ministry of Agriculture, Chengdu, Sichuan 610041, PR China
| | - Gang Yang
- Institute of Ecological and Environmental Sciences, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China
| | - Yanzong Zhang
- Institute of Ecological and Environmental Sciences, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China
| | - Yaodong Hu
- Institute of Animal Genetics and Breeding, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China
| | - Jing Zhang
- Institute of Ecological and Environmental Sciences, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China
| | - Shihuai Deng
- Institute of Ecological and Environmental Sciences, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China
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8
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Bussemaker MJ, Mu X, Zhang D. Ultrasonic Pretreatment of Wheat Straw in Oxidative and Nonoxidative Conditions Aided with Microwave Heating. Ind Eng Chem Res 2013. [DOI: 10.1021/ie401181f] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Madeleine J. Bussemaker
- Centre for Energy (M473), The University of Western Australia, 35 Stirling Highway,
Crawley, WA 6009, Australia
| | - Xindong Mu
- Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Laoshan District,
Qingdao 266101, Shandong, China
| | - Dongke Zhang
- Centre for Energy (M473), The University of Western Australia, 35 Stirling Highway,
Crawley, WA 6009, Australia
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Um BH, van Walsum GP. Effect of Pretreatment Severity on Accumulation of Major Degradation Products from Dilute Acid Pretreated Corn Stover and Subsequent Inhibition of Enzymatic Hydrolysis of Cellulose. Appl Biochem Biotechnol 2012; 168:406-20. [DOI: 10.1007/s12010-012-9784-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Accepted: 06/21/2012] [Indexed: 10/28/2022]
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10
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Lee DH, Cho EY, Kim CJ, Kim SB. Pretreatment of waste newspaper using ethylene glycol for bioethanol production. BIOTECHNOL BIOPROC E 2011. [DOI: 10.1007/s12257-010-0158-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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11
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Han M, Kim Y, Kim Y, Chung B, Choi GW. Bioethanol production from optimized pretreatment of cassava stem. KOREAN J CHEM ENG 2010. [DOI: 10.1007/s11814-010-0330-4] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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12
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Um BH, van Walsum GP. Mass balance on green liquor pre-pulping extraction of northeast mixed hardwood. BIORESOURCE TECHNOLOGY 2010; 101:5978-5987. [PMID: 20392634 DOI: 10.1016/j.biortech.2010.03.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2009] [Revised: 03/01/2010] [Accepted: 03/01/2010] [Indexed: 05/29/2023]
Abstract
A forest biorefinery configuration employing a hemicellulose pre-pulping extraction is being investigated that will retain pulp yields, reduce the organic and inorganic load for liquor recovery, and create a hemicellulose feed stream for the generation of biofuels and biomaterials. Current efforts are focused on developing extract production and conditioning processes that will result in fermentable sugars suitable for conversion to fuel alcohols or organic acid chemical products. As efforts move the process closer to commercial demonstration, it is apparent that a high level of confidence is needed in the analysis of the partitioning of fresh wood into its extracted wood and liquid extract fractions. Of particular interest is the partitioning of the carbohydrates, as these constitute the feedstock for bioconversion to fuels and chemicals. The extraction method employed utilizes green liquor derived from the kraft pulping process for pretreatment of the woodchips. To enable analysis, green liquor extraction was followed by 4% sulfuric acid hydrolysis to complete hydrolysis of the oligomers that were still present. High performance anion-exchange chromatography (HPAEC-PAD) and high performance liquid chromatography (HPLC) methods were used to analyze the carbohydrates in northern hardwood and its extract fractions. The Bio-Rad Aminex HPX-87H column did not separate mannose, xylose, and galactose, but the area of the collective peak corresponds well to the sum of these components as measured by HPAEC. In addition to sugars, standard methods were employed for quantification of the individual components (e.g., lignin, ash, nitrogen, carbon, extractives, uronic and acetic acid). The analytical mass balance closure was 102.2% and 103.6% for raw wood, 99.3% and 102.3% for extracted wood, and 94.7% and 95.6% for hemicellulose extract from the HPAEC and HPLC, respectively. The extraction mass balance was 96.9% and 98.2% for HPAEC and HPLC, respectively. The data generated by this analysis are important to further design work in commercializing the pulp and biorefinery processes.
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Affiliation(s)
- Byung-Hwan Um
- Forest Bioproducts Research Initiative, Department of Chemical and Biological Engineering, University of Maine, Orono, ME 04469, USA
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Um BH, van Walsum GP. Evaluation of enzyme mixtures in releasing fermentable sugars from pre-pulping extracts of mixed northeast hardwoods. Appl Biochem Biotechnol 2010; 161:432-47. [PMID: 20084471 DOI: 10.1007/s12010-009-8887-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2009] [Accepted: 12/07/2009] [Indexed: 11/24/2022]
Abstract
One near-term option to developing a forest product biorefinery is to derive pre-pulping extract from incoming wood chips before the main pulping step. The release of monomer sugars from a xylan-rich extract, creating a fermentable substrate is a prerequisite for utilization of pre-pulping extract for production of ethanol or other value-added products. This study examined the individual and mixture efficiencies of two hemicellulolytic microbial enzymes and two xylanase preparations in catalyzing degradation of green liquor (GL) and hot water (HW) pre-pulping extracts. The effects of four commercial enzyme preparations were determined by assessing yields of xylose + galactose + mannose (xmg) obtained under different reaction conditions. Of the individual enzyme preparations tested, a sample NS 50012 was superior to the other enzyme preparations in releasing xmg under conditions optimized for separate hydrolysis and fermentation and for simultaneous saccharification and fermentation. In comparison to pre-pulping extracts treated with HW, extract treated with GL was found to inhibit the action of all tested enzymes. This inhibition may be related to higher salt and lignin phenol in the GL extract. On both types of extracts, the mixture constituted by NS 50012 and NS 50030 provided the highest yield of hemicellulose conversion at 55 degrees C and pH 5.5. The generated digestibility thus signified that the synergistic effectiveness in xylan + galactan + mannan (XMG) hydrolysis between NS 50012 (from Aspergillus aculeatus) and NS 50030 (from Aspergillus oryzae) is the result of an interaction mechanism involving different XMG-degrading enzyme activities in the two enzyme preparations.
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Affiliation(s)
- Byung-Hwan Um
- Forest Bioproducts Research Initiative, Department of Chemical and Biological Engineering, University of Maine, Orono, ME 04469, USA
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Optimizing dilute-acid pretreatment of rapeseed straw for extraction of hemicellulose. Appl Biochem Biotechnol 2010; 161:22-33. [PMID: 20087686 DOI: 10.1007/s12010-009-8898-z] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Accepted: 12/22/2009] [Indexed: 10/20/2022]
Abstract
Biological conversion of biomass into fuels and chemicals requires hydrolysis of the polysaccharide fraction into monomeric sugars prior to fermentation. Hydrolysis can be performed enzymatically or with mineral acids. In this study, dilute sulfuric acid was used as a catalyst for the pretreatment of rapeseed straw. The purpose of this study is to optimize the pretreatment process in a 15-mL bomb tube reactor and investigate the effects of the acid concentration, temperature, and reaction time. These parameters influence hemicellulose removal and production of sugars (xylose, glucose, and arabinose) in the hydrolyzate as well as the formation of by-products (furfural, 5-hydroxymethylfurfural, and acetic acid). Statistical analysis was based on a model composition corresponding to a 3(3) orthogonal factorial design and employed the response surface methodology to optimize the pretreatment conditions, aiming to attain maximum xylan, mannan, and galactan (XMG) extraction from hemicellulose of rapeseed straw. The obtained optimum conditions were: H2SO4 concentration of 1.76% and temperature of 152.6 degrees C with a reaction time of 21 min. Under these optimal conditions, 85.5% of the total sugar was recovered after acid hydrolysis (78.9% XMG and 6.6% glucan). The hydrolyzate contained 1.60 g/L glucose, 0.61 g/L arabinose, 10.49 g/L xylose, mannose, and galactose, 0.39 g/L cellobiose, 0.94 g/L fructose, 0.02 g/L 1,6-anhydro-glucose, 1.17 g/L formic acid, 2.94 g/L acetic acid, 0.04 g/L levulinic acid, 0.04 g/L 5-hydroxymethylfurfural, and 0.98 g/L furfural.
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Abstract
Enzymatic hydrolysis of hybrid poplar treated by ammonia recycle percolation (ARP) was studied applying cellulase enzyme supplemented with additional xylanase or pectinase. The effect of xylanase addition was much more significant than pectinase addition. Conversion of ARP-treated hybrid poplar to ethanol was carried out by simultaneous saccharification and fermentation (SSF) and SS and cofermentation (SSCF). The maximum ethanol yield observed from the SSCF experiment was 78% of theoretical maximum based on the total carbohydrate (glucan + xylan). The same feedstock was also treated by soaking in aqueous ammonia (SAA), a batch pretreatment process with lower severity than ARP. The test results indicated that relatively high severity is required to attain acceptable level of digestibility of hybrid poplar. In order to lower the severity of the pretreatment, addition of H(2)O(2) was attempted in the SAA. Addition of H(2)O(2) significantly enhanced delignification of hybrid poplar due to its oxidative degradation of lignin. Several different H(2)O(2) feeding schemes and different temperature profiles were attempted in operation of the SAA to investigate the effects of H(2)O(2) on degradation of lignin and carbohydrates in hybrid poplar. More than 60% of lignin in hybrid poplar was removed with stepwise-increase of temperature (60-120 degrees C after 4h of reaction). Increase of carbohydrate degradation was also observed under this condition.
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Affiliation(s)
- Rajesh Gupta
- Dept. of Chemical Engineering, Auburn University, AL 36849, USA
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Kumar R, Wyman CE. Effects of cellulase and xylanase enzymes on the deconstruction of solids from pretreatment of poplar by leading technologies. Biotechnol Prog 2009; 25:302-14. [DOI: 10.1002/btpr.102] [Citation(s) in RCA: 211] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Silverstein RA, Chen Y, Sharma-Shivappa RR, Boyette MD, Osborne J. A comparison of chemical pretreatment methods for improving saccharification of cotton stalks. BIORESOURCE TECHNOLOGY 2007; 98:3000-11. [PMID: 17158046 DOI: 10.1016/j.biortech.2006.10.022] [Citation(s) in RCA: 175] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Accepted: 10/12/2006] [Indexed: 05/08/2023]
Abstract
The effectiveness of sulfuric acid (H(2)SO(4)), sodium hydroxide (NaOH), hydrogen peroxide (H(2)O(2)), and ozone pretreatments for conversion of cotton stalks to ethanol was investigated. Ground cotton stalks at a solid loading of 10% (w/v) were pretreated with H(2)SO(4), NaOH, and H(2)O(2) at concentrations of 0.5%, 1%, and 2% (w/v). Treatment temperatures of 90 degrees C and 121 degrees C at 15 psi were investigated for residence times of 30, 60, and 90 min. Ozone pretreatment was performed at 4 degrees C with constant sparging of stalks in water. Solids from H(2)SO(4), NaOH, and H(2)O(2) pretreatments (at 2%, 60 min, 121 degrees C/15 psi) showed significant lignin degradation and/or high sugar availability and hence were hydrolyzed by Celluclast 1.5L and Novozym 188 at 50 degrees C. Sulfuric acid pretreatment resulted in the highest xylan reduction (95.23% for 2% acid, 90 min, 121 degrees C/15 psi) but the lowest cellulose to glucose conversion during hydrolysis (23.85%). Sodium hydroxide pretreatment resulted in the highest level of delignification (65.63% for 2% NaOH, 90 min, 121 degrees C/15 psi) and cellulose conversion (60.8%). Hydrogen peroxide pretreatment resulted in significantly lower (p<or=0.05) delignification (maximum of 29.51% for 2%, 30 min, 121 degrees C/15 psi) and cellulose conversion (49.8%) than sodium hydroxide pretreatment, but had a higher (p<or=0.05) cellulose conversion than sulfuric acid pretreatment. Ozone did not cause any significant changes in lignin, xylan, or glucan contents over time. Quadratic models using time, temperature, and concentration as continuous variables were developed to predict xylan and lignin reduction, respectively for sulfuric acid and sodium hydroxide pretreatments. In addition, a modified severity parameter (log M(0)) was constructed and explained most of the variation in xylan or lignin reduction through simple linear regressions.
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Affiliation(s)
- Rebecca A Silverstein
- Department of Biological and Agricultural Engineering, Campus Box 7625, North Carolina State University, Raleigh, NC 27695-7625, USA
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Substrate Dependency and Effect of Xylanase Supplementation on Enzymatic Hydrolysis of Ammonia-Treated Biomass. Appl Biochem Biotechnol 2007; 148:59-70. [DOI: 10.1007/s12010-007-8071-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2007] [Accepted: 09/27/2007] [Indexed: 10/22/2022]
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