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Jia W, Zhou M, Yang C, Zhang H, Niu M, Shi H. Evaluating Process of Auto-Hydrolysis Prior to Kraft Pulping on Production of Chemical Pulp for End Used Paper-Grade Products. JOURNAL OF BIORESOURCES AND BIOPRODUCTS 2022. [DOI: 10.1016/j.jobab.2022.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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Jia W, Zhou M, Sun Y, Niu M, Shi H. Evaluating Process of Auto-Hydrolysis Prior to Kraft Pulping on Production of Chemical Pulp for End Used Paper-Grade Products. JOURNAL OF BIORESOURCES AND BIOPRODUCTS 2022. [DOI: 10.1016/j.jobab.2022.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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Cardoon Hydrolysate Detoxification by Activated Carbon or Membranes System for Bioethanol Production. ENERGIES 2022. [DOI: 10.3390/en15061993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
Advanced biofuels incorporation into the transportation sector, particularly cellulosic bioethanol, is crucial for attaining carbon neutrality by 2050, contributing to climate changes mitigation and wastes minimization. The world needs biofuel to be commercially available to tackle the socioeconomic challenges coming from the continued use of fossil fuels. Cynara cardunculus (cardoon) is a cheap lignocellulosic raw biomass that easily grows in Mediterraneous soils and is a potential renewable resource for a biorefinery. This work aimed to study the bioethanol production from cardoon hemicellulosic hydrolysates, which originated from dilute sulfuric acid hydrolysis pretreatment. A detoxification step to remove released microbial fermentative inhibitors was evaluated by using both activated carbon adsorption and a nanofiltration membrane system. The Scheffersomyces stipitis CBS5773 yeast and the modified Escherichia coli MS04 fermentation performances at different experimental conditions were compared. The promising results with E. coli, using detoxified cardoon by membrane nanofiltration, led to a bioethanol volumetric productivity of 0.30 g·L−1·h−1, with a conversion efficiency of 94.5%. Regarding the S. stipitis, in similar fermentation conditions, volumetric productivity of 0.091 g·L−1·h−1 with a conversion efficiency of 64.9% was obtained. Concluding, the production of bioethanol through detoxification of hemicellulosic cardoon hydrolysate presents a suitable alternative for the production of second-generation bioethanol, especially using the modified E. coli.
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Wierzbicki MP, Maloney V, Mizrachi E, Myburg AA. Xylan in the Middle: Understanding Xylan Biosynthesis and Its Metabolic Dependencies Toward Improving Wood Fiber for Industrial Processing. FRONTIERS IN PLANT SCIENCE 2019; 10:176. [PMID: 30858858 PMCID: PMC6397879 DOI: 10.3389/fpls.2019.00176] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2018] [Accepted: 02/04/2019] [Indexed: 05/14/2023]
Abstract
Lignocellulosic biomass, encompassing cellulose, lignin and hemicellulose in plant secondary cell walls (SCWs), is the most abundant source of renewable materials on earth. Currently, fast-growing woody dicots such as Eucalyptus and Populus trees are major lignocellulosic (wood fiber) feedstocks for bioproducts such as pulp, paper, cellulose, textiles, bioplastics and other biomaterials. Processing wood for these products entails separating the biomass into its three main components as efficiently as possible without compromising yield. Glucuronoxylan (xylan), the main hemicellulose present in the SCWs of hardwood trees carries chemical modifications that are associated with SCW composition and ultrastructure, and affect the recalcitrance of woody biomass to industrial processing. In this review we highlight the importance of xylan properties for industrial wood fiber processing and how gaining a greater understanding of xylan biosynthesis, specifically xylan modification, could yield novel biotechnology approaches to reduce recalcitrance or introduce novel processing traits. Altering xylan modification patterns has recently become a focus of plant SCW studies due to early findings that altered modification patterns can yield beneficial biomass processing traits. Additionally, it has been noted that plants with altered xylan composition display metabolic differences linked to changes in precursor usage. We explore the possibility of using systems biology and systems genetics approaches to gain insight into the coordination of SCW formation with other interdependent biological processes. Acetyl-CoA, s-adenosylmethionine and nucleotide sugars are precursors needed for xylan modification, however, the pathways which produce metabolic pools during different stages of fiber cell wall formation still have to be identified and their co-regulation during SCW formation elucidated. The crucial dependence on precursor metabolism provides an opportunity to alter xylan modification patterns through metabolic engineering of one or more of these interdependent pathways. The complexity of xylan biosynthesis and modification is currently a stumbling point, but it may provide new avenues for woody biomass engineering that are not possible for other biopolymers.
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Affiliation(s)
| | | | | | - Alexander A. Myburg
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, South Africa
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Detoxification of Organosolv-Pretreated Pine Prehydrolysates with Anion Resin and Cysteine for Butanol Fermentation. Appl Biochem Biotechnol 2018; 186:662-680. [PMID: 29717408 DOI: 10.1007/s12010-018-2769-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 04/23/2018] [Indexed: 10/17/2022]
Abstract
Bioconversion of lignocellulose to biofuels suffers from the degradation compounds formed during pretreatment and acid hydrolysis. In order to achieve an efficient biomass to biofuel conversion, detoxification is often required before enzymatic hydrolysis and microbial fermentation. Prehydrolysates from ethanol organosolv-pretreated pine wood were used as substrates in butanol fermentation in this study. Six detoxification approaches were studied and compared, including overliming, anion exchange resin, nonionic resin, laccase, activated carbon, and cysteine. It was observed that detoxification by anion exchange resin was the most effective method. The final butanol yield after anion exchange resin treatment was comparable to the control group, but the fermentation was delayed for 72 h. The addition of Ca(OH)2 was found to alleviate this delay and improve the fermentation efficiency. The combination of Ca(OH)2 and anion exchange resin resulted in completion of fermentation within 72 h and acetone-butanol-ethanol (ABE) production of 11.11 g/L, corresponding to a yield of 0.21 g/g sugar. The cysteine detoxification also resulted in good detoxification performance, but promoted fermentation towards acid production (8.90 g/L). The effect of salt on ABE fermentation was assessed and the possible role of Ca(OH)2 was to remove the salts in the prehydrolysates by precipitation.
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Coz A, Llano T, Cifrián E, Viguri J, Maican E, Sixta H. Physico-Chemical Alternatives in Lignocellulosic Materials in Relation to the Kind of Component for Fermenting Purposes. MATERIALS 2016; 9:ma9070574. [PMID: 28773700 PMCID: PMC5456911 DOI: 10.3390/ma9070574] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 07/04/2016] [Accepted: 07/08/2016] [Indexed: 11/16/2022]
Abstract
The complete bioconversion of the carbohydrate fraction is of great importance for a lignocellulosic-based biorefinery. However, due to the structure of the lignocellulosic materials, and depending basically on the main parameters within the pretreatment steps, numerous byproducts are generated and they act as inhibitors in the fermentation operations. In this sense, the impact of inhibitory compounds derived from lignocellulosic materials is one of the major challenges for a sustainable biomass-to-biofuel and -bioproduct industry. In order to minimise the negative effects of these compounds, numerous methodologies have been tested including physical, chemical, and biological processes. The main physical and chemical treatments have been studied in this work in relation to the lignocellulosic material and the inhibitor in order to point out the best mechanisms for fermenting purposes. In addition, special attention has been made in the case of lignocellulosic hydrolysates obtained by chemical processes with SO₂, due to the complex matrix of these materials and the increase in these methodologies in future biorefinery markets. Recommendations of different detoxification methods have been given.
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Affiliation(s)
- Alberto Coz
- Green Engineering and Resources, Department of Chemistry and Process and Resource Engineering, University of Cantabria, Avda. Los Castros s/n, Santander 39005, Spain.
| | - Tamara Llano
- Green Engineering and Resources, Department of Chemistry and Process and Resource Engineering, University of Cantabria, Avda. Los Castros s/n, Santander 39005, Spain.
| | - Eva Cifrián
- Green Engineering and Resources, Department of Chemistry and Process and Resource Engineering, University of Cantabria, Avda. Los Castros s/n, Santander 39005, Spain.
| | - Javier Viguri
- Green Engineering and Resources, Department of Chemistry and Process and Resource Engineering, University of Cantabria, Avda. Los Castros s/n, Santander 39005, Spain.
| | - Edmond Maican
- Faculty of Biotechnical Systems Engineering, Politehnica University of Bucharest, 313 Splaiul Independentei, Sector 6, Bucuresti 060042, Romania.
| | - Herbert Sixta
- Department of Forest Products Technology, School of Chemistry, Aalto University, P.O. Box 16300, Aalto FI-00076, Finland.
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Liu Z, Li Q, Zhang C, Wang L, Han B, Li B, Zhang Y, Chen H, Xing XH. Effects of operating parameters on hydrogen production from raw wet steam-exploded cornstalk and two-stage fermentation potential for biohythane production. Biochem Eng J 2014. [DOI: 10.1016/j.bej.2014.06.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Brás T, Guerra V, Torrado I, Lourenço P, Carvalheiro F, Duarte LC, Neves LA. Detoxification of hemicellulosic hydrolysates from extracted olive pomace by diananofiltration. Process Biochem 2014. [DOI: 10.1016/j.procbio.2013.09.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Guo X, Cavka A, Jönsson LJ, Hong F. Comparison of methods for detoxification of spruce hydrolysate for bacterial cellulose production. Microb Cell Fact 2013; 12:93. [PMID: 24119691 PMCID: PMC3856561 DOI: 10.1186/1475-2859-12-93] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Accepted: 10/09/2013] [Indexed: 11/17/2022] Open
Abstract
Background Bacterial cellulose (BC) is a nanostructured material with unique properties and wide applicability. In order to decrease the production cost of bacterial cellulose, lignocellulose-based media have considerable potential as alternative cost-effective feedstocks. However, pretreatment and enzymatic hydrolysis of lignocellulose to sugars also generate fermentation inhibitors. Detoxification of lignocellulosic hydrolysates is needed to achieve efficient production of BC. In this investigation, different methods for detoxification of spruce hydrolysate prior to production of BC were compared with respect to effects on potential inhibitors and fermentable sugars, sugar consumption, BC yield, and cell viability. The objectives were to identify efficient detoxification methods and to achieve a better understanding of the role played by different inhibitors in lignocellulosic hydrolysates. Results In a first series of experiments, the detoxification methods investigated included treatments with activated charcoal, alkali [sodium hydroxide, calcium hydroxide (overliming), and ammonium hydroxide], anion and cation ion-exchange resins, and reducing agents (sodium sulfite and sodium dithionite). A second series of detoxification experiments included enzymatic treatments (laccase and peroxidase). The potential inhibitors studied included aliphatic acids, furan aldehydes, and phenolic compounds. The best effects in the first series of detoxification experiments were achieved with activated charcoal and anion exchanger. After detoxification with activated charcoal the BC yield was 8.2 g/L, while it was 7.5 g/L in a reference medium without inhibitors. Treatments with anion exchanger at pH 10 and pH 5.5 gave a BC yield of 7.9 g/L and 6.3 g/L, respectively. The first series of experiments suggested that there was a relationship between the BC yield and phenolic inhibitors. Therefore, the second series of detoxification experiments focused on treatments with phenol-oxidizing enzymes. The BC yield in the laccase-detoxified hydrolysate reached 5.0-5.5 g/L after 14 days cultivation, which demonstrated the important inhibitory role played by phenolic compounds. Conclusions The investigation shows that detoxification methods that efficiently remove phenolics benefit bacterial growth and BC production. Negative effects of salts could not be excluded and the osmotolerance of Gluconacetobacter xylinus needs to be further investigated in the future. Combinations of detoxification methods that efficiently decrease the concentration of inhibitors remain as an interesting option.
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Affiliation(s)
- Xiang Guo
- China-Sweden Associated Research Laboratory in Industrial Biotechnology, College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China.
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Alonso JL, Domínguez H, Garrote G, González-Muñoz M, Gullón B, Moure A, Santos V, Vila C, Yáñez R. Biorefinery processes for the integral valorization of agroindustrial and forestal wastes Procesos de biorrefinería para la valorización integral de residuos agroindustriales y forestales. CYTA - JOURNAL OF FOOD 2011. [DOI: 10.1080/19476337.2011.598949] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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Soto ML, Moure A, Domínguez H, Parajó JC. Recovery, concentration and purification of phenolic compounds by adsorption: A review. J FOOD ENG 2011. [DOI: 10.1016/j.jfoodeng.2011.02.010] [Citation(s) in RCA: 331] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Conde E, Gullón P, Moure A, Domínguez H, Parajó JC. Fractionation of industrial solids containing barley husks in aqueous media. FOOD AND BIOPRODUCTS PROCESSING 2009. [DOI: 10.1016/j.fbp.2009.03.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Optimization of the pretreatment of rice straw hemicellulosic hydrolyzates for microbial production of xylitol. BIOTECHNOL BIOPROC E 2007. [DOI: 10.1007/bf02931063] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Solenzal AIN, Aroche YO, Verde MV, Santana EM, Martínez EA. PURIFICACIÓN DE HIDROLIZADO DE BAGAZO DE CAÑA DE AZÚCAR CON CARBÓN ACTIVADO Y RESINAS DE INTERCAMBIO IÓNICO PURIFICATION OF SUGARCANE BAGASSE HYDROLYSATES USING ACTIVATED CHARCOAL AND ION-EXCHANGE RESINS. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/11358120609487682] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Mussatto SI, Santos JC, Filho WCR, Silva SS. Purification of Xylitol from Fermented Hemicellulosic Hydrolyzate Using Liquid–Liquid Extraction and Precipitation Techniques. Biotechnol Lett 2005; 27:1113-5. [PMID: 16132861 DOI: 10.1007/s10529-005-8458-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2005] [Revised: 03/23/2005] [Accepted: 05/24/2005] [Indexed: 11/28/2022]
Abstract
Xylitol was produced by Candida guilliermondii by fermentation of sugarcane bagasse hemicellulosic hydrolysate. Undesirable impurities were extracted from the broth using either ethyl acetate, chloroform or dichloromethane. The best results on clarification of the broth without xylitol loss were obtained with ethyl acetate. When ethanol, acetone or tetrahydrofuran were used for precipitation of impurities, only tetrahydrofuran clarified the fermented broth, but a high xylitol loss (approximately 30%) was observed.
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Affiliation(s)
- Solange I Mussatto
- Department of Biotechnology, Faculty of Chemical Engineering of Lorena, Rodovia Itajubá-Lorena Km 74, 5-CEP, 12600-970, Lorena, SP, Brazil
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Carvalheiro F, Duarte L, Lopes S, Parajó J, Pereira H, Gı́rio F. Evaluation of the detoxification of brewery’s spent grain hydrolysate for xylitol production by Debaryomyces hansenii CCMI 941. Process Biochem 2005. [DOI: 10.1016/j.procbio.2004.04.015] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Cantarella M, Cantarella L, Gallifuoco A, Spera A, Alfani F. Comparison of different detoxification methods for steam-exploded poplar wood as a substrate for the bioproduction of ethanol in SHF and SSF. Process Biochem 2004. [DOI: 10.1016/s0032-9592(03)00285-1] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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González J, Cruz J, Domı́nguez H, Parajó J. Production of antioxidants from Eucalyptus globulus wood by solvent extraction of hemicellulose hydrolysates. Food Chem 2004. [DOI: 10.1016/s0308-8146(03)00208-5] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Rivas B, Domı́nguez J, Domı́nguez H, Parajó J. Bioconversion of posthydrolysed autohydrolysis liquors: an alternative for xylitol production from corn cobs. Enzyme Microb Technol 2002. [DOI: 10.1016/s0141-0229(02)00098-4] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Garrote G, Domínguez H, Parajó JC. Generation of xylose solutions from Eucalyptus globulus wood by autohydrolysis-posthydrolysis processes: posthydrolysis kinetics. BIORESOURCE TECHNOLOGY 2001; 79:155-64. [PMID: 11480924 DOI: 10.1016/s0960-8524(01)00044-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Eucalyptus wood samples were treated with water under selected operational conditions (autohydrolysis reaction) to obtain a liquid phase containing hemicellulose-decomposition products (mainly acetylated xylooligosaccharides, xylose and acetic acid). In a further acid-catalysed step (posthydrolysis reaction), xylooligosaccharides were converted into xylose, a carbon source for further fermentation. The kinetic pattern governing the posthydrolysis step was established by reacting xylooligosaccharide-containing liquors at 100.5 degrees C, 115 degrees C, 125 degrees C or 135 degrees C in media containing 0.5, 1.0, 1.5 or 2 wt% of catalyst (sulphuric acid). The time course of the concentrations of xylooligosaccharides, xylose, furfural and acetic acid were determined, and the results were interpreted by means of a kinetic model which allowed a close reproduction of the experimental data. Almost quantitative conversion of xylooligosaccharides into xylose was achieved under a variety of experimental conditions. The first-order, kinetic coefficient for xylooligosaccharide hydrolysis (k1, h(-1)) varied with both temperature (T, K) and molar sulphuric acid concentration (C) according to the equation In k1 = 36.66 + 1.00lnC - 108.0/(8.314T). The hydrolysis of acetyl groups followed a first-order kinetics. The corresponding kinetic coefficient (ka, h(-1) was correlated with the operational conditions by the equation Inka = 26.80+ 1.18 InC - 73.37/(8.314T).
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Affiliation(s)
- G Garrote
- Chemical Engineering Department, University of Vigo, Edificio Politécnico, Ourense, Spain
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Cruz JM, Domínguez JM, Domínguez H, Parajó JC. Antioxidant and antimicrobial effects of extracts from hydrolysates of lignocellulosic materials. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2001; 49:2459-2464. [PMID: 11368620 DOI: 10.1021/jf001237h] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The antioxidant and antimicrobial activities of ethyl acetate extracts obtained from acid hydrolysates of several lignocellulosic materials (Eucalyptus globulus wood, barley bran, corn cobs, and corn leaves) were evaluated. The minimum inhibitory and bactericide concentrations (MIC and MBC, respectively) were determined against a selection of bacteria and yeasts. Extracts from Eucalyptus wood hydrolysates were the most active for inhibiting bacteria and yeast growth, with MIC in the range of 10(2)--5 x 10(3) microg/mL and MBC in the range of 10(3)--0(5) microg/mL. Bacteriogenic and bacteriostatic activities of extracts from Eucalyptus wood and barley bran acid hydrolysates were slightly higher than those of corn cobs and leaves. Both the radical scavenging capacity and the inhibition of the beta-carotene bleaching caused by extracts were determined and compared with those of synthetic antioxidants. The antioxidant activity of extracts increased with their concentrations in the media, the stronger properties corresponding to those obtained from Eucalyptus wood hydrolysates.
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Affiliation(s)
- J M Cruz
- Departamento de Enxeñería Química, Universidade de Vigo, Campus Ourense, Edificio Politécnico, As Lagoas, 32004 Ourense, Spain
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Latif F, Rajoka MI. Production of ethanol and xylitol from corn cobs by yeasts. BIORESOURCE TECHNOLOGY 2001; 77:57-63. [PMID: 11211076 DOI: 10.1016/s0960-8524(00)00134-6] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Saccharomyces cerevisiae and Candida tropicalis were used separately and as co-culture for simultaneous saccharification and fermentation (SSF) of 5-20% (w/v) dry corn cobs. A maximal ethanol concentration of 27, 23, 21 g/l (w/v) from 200 g/l (w/v) dry corn cobs was obtained by S. cerevisiae, C. tropicalis and the co-culture, respectively, after 96 h of fermentation. However, theoretical yields of 82%, 71% and 63% were observed from 50 g/l dry corn cobs for the above cultures, respectively. Maximal xylitol concentration of 21, 20 and 15 g/l from 200 g/l (w/v) dry corn cobs was obtained by C. tropicalis, co-culture, and S. cerevisiae, respectively. Maximum theoretical yields of 79.0%, 77.0% and 58% were observed from 50 g/l of corn cobs, respectively. The volumetric productivities for ethanol and xylitol increased with the increase in substrate concentration, whereas, yield decreased. Glycerol and acetic acid were formed as minor by-products. S. cerevisiae and C. tropicalis resulted in better product yields (0.42 and 0.36 g/g) for ethanol and (0.52 and 0.71 g/g) for xylitol, respectively, whereas, the co-culture showed moderate level of ethanol (0.32 g/g) and almost maximal levels of xylitol (0.69 g/g).
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Affiliation(s)
- F Latif
- National Institute for Biotechnology and Genetic Engineering, Faisalabad, Pakistan
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The effect of overliming on the toxicity of dilute acid pretreated lignocellulosics: the role of inorganics, uronic acids and ether-soluble organics. Enzyme Microb Technol 2000; 27:240-247. [PMID: 10899549 DOI: 10.1016/s0141-0229(00)00216-7] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Although the treatment of dilute acid pretreated lignocellulosics with calcium hydroxide or carbonate (overliming) is known to improve the fermentability of carbohydrate-rich hydrolyzate streams, a firm understanding of the chemistry behind the process is lacking. Quantitative evaluation of inorganics, uronic acids, and non-polar organics indicates that only a portion of the improvement can be ascribed to these materials. Upon overliming the concentrations of inorganics either increase (Ca, Mg), decrease (Fe, P, Zn, K) or remain relatively the same (Al, Na). Furthermore, organic compounds that are not extractable with tert-butyl methyl ether (MTBE) are toxic to Zymomonas mobilis CP4(pZB5). Overliming and direct neutralization are somewhat effective in removing sulfate anions, although sulfate toxicity is considerably less than that of acetic acid. Uronic acids were found to be non-toxic under pH controlled conditions.
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Cruz JM, Domínguez JM, Domínguez H, Parajó JC. Preparation of fermentation media from agricultural wastes and their bioconversion into xylitol. FOOD BIOTECHNOL 2000. [DOI: 10.1080/08905430009549981] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Cruz JM, Domı́nguez JM, Domı́nguez H, Parajó JC. Solvent extraction of hemicellulosic wood hydrolysates: a procedure useful for obtaining both detoxified fermentation media and polyphenols with antioxidant activity. Food Chem 1999. [DOI: 10.1016/s0308-8146(99)00106-5] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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