Sustainability of cereal straws for the fermentative production of second generation biofuels: A review of the efficiency and economics of biochemical pretreatment processes

Straws of cereal grains represent the major fraction of lignocellulosic agricultural wastes generated worldwide. Cereal straws (CSs) hold great potential for implementation as candidate feedstocks for fermentative production of second generation (2G) biofuels. Among the different varieties of CSs, rice and wheat straw are clearly the best available options for development of a reliable feedstock base from all aspects. Feasible alternatives of costly, energy intensive and non-ecofriendly physical and chemical pretreatments are needed to facilitate full scale utilization of the CSs in the 2G biofuel platforms. Biochemical pretreatments of CSs using potential lignocellulolytic microorganisms can become the alternative technology upon proper exploration and exploitation. In the present review article, efficiency of the microorganism mediated biochemical processes has been assessed as promising pretreatment methods for CSs. Ligninolytic action of different fungi, bacteria and microbial consortia on different CSs (mostly wheat and rice straw) has been evaluated on the basis of extent of lignin degradation, selectivity of degradation and sugar recovery from pretreated CSs. Utilization of microbial consortia has been recommended as better pretreatment agents in comparison to their mono-culture counterparts. The review also attempts to predict the economic viability of biochemical pretreatments on the basis of associated cost factor correlation with the physical and chemical processes. Construction of synergistically operating lignocellulolytic microbial consortia for application in biochemical pretreatments of CSs has been demonstrated in the article and advocated as a promising process amelioration strategy. Overall, the review affirms the biochemical processes as the most suitable pretreatment technique from techno-economic and environmental aspects.

[1]  John Sessions,et al.  Using sulfite chemistry for robust bioconversion of Douglas-fir forest residue to bioethanol at high titer and lignosulfonate: a pilot-scale evaluation. , 2015, Bioresource technology.

[2]  Carlos Martín,et al.  Pretreatment of lignocellulose: Formation of inhibitory by-products and strategies for minimizing their effects. , 2016, Bioresource technology.

[3]  Yonghua Zhu,et al.  Isolation of a rice endophytic bacterium, Pantoea sp. Sd‐1, with ligninolytic activity and characterization of its rice straw degradation ability , 2014, Letters in applied microbiology.

[4]  P. García-Encina,et al.  Effect of thermal, acid, alkaline and alkaline-peroxide pretreatments on the biochemical methane potential and kinetics of the anaerobic digestion of wheat straw and sugarcane bagasse. , 2016, Bioresource technology.

[5]  C. Wan,et al.  Effectiveness of microbial pretreatment by Ceriporiopsis subvermispora on different biomass feedstocks. , 2011, Bioresource technology.

[6]  Xuebing Zhao,et al.  A comparison of several organosolv pretreatments for improving the enzymatic hydrolysis of wheat straw: Substrate digestibility, fermentability and structural features , 2015 .

[7]  G. Suen,et al.  Cellulose-degrading bacteria associated with the invasive woodwasp Sirex noctilio , 2011, The ISME Journal.

[8]  Jo‐Shu Chang,et al.  Biohydrogen production from lignocellulosic feedstock. , 2011, Bioresource technology.

[9]  H. Zabed,et al.  Fuel ethanol production from lignocellulosic biomass: An overview on feedstocks and technological approaches , 2016 .

[10]  J. Carlson,et al.  Lignin degradation in wood-feeding insects , 2008, Proceedings of the National Academy of Sciences.

[11]  B. Pletschke,et al.  A review of lignocellulose bioconversion using enzymatic hydrolysis and synergistic cooperation between enzymes--factors affecting enzymes, conversion and synergy. , 2012, Biotechnology advances.

[12]  K. Karimi,et al.  Improvement of biogas production from pine wood by alkali pretreatment , 2013 .

[13]  R. Dinsdale,et al.  Mesophilic biohydrogen production from calcium hydroxide treated wheat straw , 2014 .

[14]  Kristin E. Burnum-Johnson,et al.  The fungus gardens of leaf-cutter ants undergo a distinct physiological transition during biomass degradation. , 2014, Environmental microbiology reports.

[15]  Emmanuel G. Koukios,et al.  Dilute-acid pretreatment of barley straw for biological hydrogen production using Caldicellulosiruptor saccharolyticus , 2012 .

[16]  Tatiana Alves Rigamonte Fernandes,et al.  Laccases from Actinobacteria —What We Have and What to Expect , 2014 .

[17]  C. Wyman,et al.  Pretreatment: the key to unlocking low‐cost cellulosic ethanol , 2008 .

[18]  Fernando Fdz-Polanco,et al.  Biomethane potential of wheat straw: Influence of particle size, water impregnation and thermal hydrolysis , 2014 .

[19]  M Ljunggren,et al.  Techno-economic comparison of a biological hydrogen process and a 2nd generation ethanol process using barley straw as feedstock. , 2011, Bioresource technology.

[20]  G. Najafi,et al.  Lignocellulosic biomass to bioethanol, a comprehensive review with a focus on pretreatment , 2013 .

[21]  Sang Jun Sim,et al.  Thermophilic hydrogen fermentation from Korean rice straw by Thermotoga neapolitana , 2010 .

[22]  Yalei Zhang,et al.  Effect of Ca(OH)2 pretreatment on extruded rice straw anaerobic digestion. , 2015, Bioresource technology.

[23]  Xuebing Zhao,et al.  Biomass recalcitrance. Part I: the chemical compositions and physical structures affecting the enzymatic hydrolysis of lignocellulose , 2012 .

[24]  Renqiang Li,et al.  Combination of RNA sequencing and metabolite data to elucidate improved toxic compound tolerance and butanol fermentation of Clostridium acetobutylicum from wheat straw hydrolysate by supplying sodium sulfide. , 2015, Bioresource technology.

[25]  K. Kiyoshi,et al.  Butanol production from alkali-pretreated rice straw by co-culture of Clostridium thermocellum and Clostridium saccharoperbutylacetonicum. , 2015, Bioresource technology.

[26]  Zsófia Kádár,et al.  Utilization of hydrothermally pretreated wheat straw for production of bioethanol and carotene-enriched biomass. , 2013, Bioresource technology.

[27]  Keat-Teong Lee,et al.  The world availability of non-wood lignocellulosic biomass for the production of cellulosic ethanol and potential pretreatments for the enhancement of enzymatic saccharification , 2016 .

[28]  P. Kaparaju,et al.  Effect of reactor configuration on biogas production from wheat straw hydrolysate. , 2009, Bioresource technology.

[29]  Anoop Singh,et al.  Production of liquid biofuels from renewable resources , 2011 .

[30]  Hongbo Yu,et al.  The promoting effect of byproducts from Irpex lacteus on subsequent enzymatic hydrolysis of bio-pretreated cornstalks , 2011, Biotechnology for biofuels.

[31]  L. Nain,et al.  Pretreatment of paddy straw with Trametes hirsuta for improved enzymatic saccharification. , 2012, Bioresource technology.

[32]  Xuan Li,et al.  Development of AFEX-based consolidated bioprocessing on wheat straw for biohydrogen production using anaerobic microflora , 2013 .

[33]  J. Vivanco,et al.  Lignocellulose Decomposition by Microbial Secretions , 2012 .

[34]  A. Tawfik,et al.  The effect of organic loading rate on bio-hydrogen production from pre-treated rice straw waste via mesophilic up-flow anaerobic reactor. , 2012, Bioresource technology.

[35]  Greg L. Hura,et al.  Fusion of Dioxygenase and Lignin-binding Domains in a Novel Secreted Enzyme from Cellulolytic Streptomyces sp. SirexAA-E* , 2013, The Journal of Biological Chemistry.

[36]  Guang-qing Liu,et al.  Pretreatment of wheat straw with potassium hydroxide for increasing enzymatic and microbial degradability. , 2014, Bioresource technology.

[37]  Qian Yang,et al.  Isolation and characterization of rice straw degrading Streptomyces griseorubens C-5 , 2010, Biodegradation.

[38]  M. Ballesteros,et al.  Study of process configuration and catalyst concentration in integrated alkaline extrusion of barley straw for bioethanol production , 2014 .

[39]  Claudio F. Lima,et al.  Differences in the chemical structure of the lignins from sugarcane bagasse and straw. , 2015 .

[40]  V. Nkemka,et al.  Biogas production from wheat straw in batch and UASB reactors: the roles of pretreatment and seaweed hydrolysate as a co-substrate. , 2013, Bioresource technology.

[41]  K. Sheng,et al.  Fungal pretreatment of rice straw with Pleurotus ostreatus and Trichoderma reesei to enhance methane production under solid-state anaerobic digestion , 2016 .

[42]  L. Nain,et al.  Evaluating biological pretreatment as a feasible methodology for ethanol production from paddy straw , 2016 .

[43]  J. Saini,et al.  Bioethanol production from wheat straw via enzymatic route employing Penicillium janthinellum cellulases. , 2014, Bioresource technology.

[44]  Aijie Wang,et al.  Lignocellulosic saccharification by a newly isolated bacterium, Ruminiclostridium thermocellum M3 and cellular cellulase activities for high ratio of glucose to cellobiose , 2016, Biotechnology for Biofuels.

[45]  J. Colodette,et al.  Cold alkaline extraction as a pretreatment for bioethanol production from eucalyptus, sugarcane bagasse and sugarcane straw , 2016 .

[46]  Pinaki Bhattacharya,et al.  Hydrogen from food processing wastes via photofermentation using Purple Non-sulfur Bacteria (PNSB) – A review , 2017 .

[47]  Dehong Hu,et al.  Localizing gene regulation reveals a staggered wood decay mechanism for the brown rot fungus Postia placenta , 2016, Proceedings of the National Academy of Sciences.

[48]  Giuseppe Mazza,et al.  Lignin in straw of herbaceous crops , 2008 .

[49]  Paul Chen,et al.  Microbial hydrolysis and fermentation of rice straw for ethanol production , 2016 .

[50]  Chad D. Lee,et al.  Harvest index and straw yield of five classes of wheat , 2016 .

[51]  I. Mateos,et al.  Influence of rumen contents’ processing method on microbial populations in the fluid and subsequent in vitro fermentation of substrates of variable composition , 2016 .

[52]  Vijayanand S. Moholkar,et al.  Feasibility of rice straw as alternate substrate for biobutanol production , 2013 .

[53]  A. Ariff,et al.  Saccharification of rice straw by cellulase from a local Trichoderma harzianum SNRS3 for biobutanol production , 2014, BMC Biotechnology.

[54]  Richard J. Murphy,et al.  Importance of policy support and feedstock prices on economic feasibility of bioethanol production from wheat straw in the UK , 2013 .

[55]  M. Cotta,et al.  Cellulosic ethanol production from green solvent-pretreated rice straw , 2016 .

[56]  R. Chowdhury,et al.  Mixed consortia in bioprocesses: role of microbial interactions , 2016, Applied Microbiology and Biotechnology.

[57]  M. Taherzadeh,et al.  Pretreatment of spruce and oak by N-methylmorpholine-N-oxide (NMMO) for efficient conversion of their cellulose to ethanol. , 2010, Bioresource technology.

[58]  Nika Alemahdi.  Enhanced mesophilic bio-hydrogen production of raw rice straw and activated sewage sludge by co-digestion , 2015 .

[59]  C. Wyman,et al.  Physical and chemical characterizations of corn stover and poplar solids resulting from leading pretreatment technologies. , 2009, Bioresource technology.

[60]  L. Nain,et al.  Insights into biological delignification of rice straw by Trametes hirsuta and Myrothecium roridum and comparison of saccharification yields with dilute acid pretreatment , 2015 .

[61]  Shinji Fujimoto,et al.  Estimation of the potential of rice straw for ethanol production and the optimum facility size for different regions in Vietnam , 2012 .

[62]  Anne S Meyer,et al.  Lignocellulose pretreatment severity - relating pH to biomatrix opening. , 2010, New biotechnology.

[63]  De-bing Jing,et al.  Controlling the simultaneous production of laccase and lignin peroxidase from Streptomyces cinnamomensis by medium formulation , 2012, Biotechnology for Biofuels.

[64]  K. Karimi,et al.  Improvement of acetone, butanol and ethanol production from rice straw by acid and alkaline pretreatments , 2013 .

[65]  C. Chu,et al.  Biohydrogen production evaluation from rice straw hydrolysate by concentrated acid pre-treatment in both batch and continuous systems , 2013 .

[66]  S. Tringe,et al.  Metagenomic Profiling Reveals Lignocellulose Degrading System in a Microbial Community Associated with a Wood-Feeding Beetle , 2013, PloS one.

[67]  K. Fackler,et al.  Successive and quantitative fractionation and extensive structural characterization of lignin from wheat straw , 2014 .

[68]  H. Abd-Elsalam,et al.  Lignin Biodegradation with Ligninolytic Bacterial Strain and Comparison of Bacillus subtilis and Bacillus sp. Isolated from Egyptian Soil , 2009 .

[69]  Shir-Ly Huang,et al.  The addition of hydrolyzed rice straw in xylose fermentation by Pichia stipitis to increase bioethanol production at the pilot-scale , 2016 .

[70]  S. Matthews,et al.  Identification of rice straw degrading microbial consortium , 2015 .

[71]  Wei Qiao,et al.  Effect of biological pretreatments in enhancing corn straw biogas production. , 2011, Bioresource technology.

[72]  B. Liu,et al.  Genomic and secretomic insight into lignocellulolytic system of an endophytic bacterium Pantoea ananatis Sd-1 , 2016, Biotechnology for Biofuels.

[73]  I. Valdez‐Vazquez,et al.  Microscopic analysis of wheat straw cell wall degradation by microbial consortia for hydrogen production , 2015 .

[74]  Ki‐Hyun Kim,et al.  Pyrolysis of wastes generated through saccharification of oak tree by using CO2 as reaction medium , 2017 .

[75]  Shu-lin Chen,et al.  Degradation of native wheat straw lignin by Streptomyces viridosporus T7A , 2013, International Journal of Environmental Science and Technology.

[76]  A. C. Chang,et al.  Hydrogen production by the anaerobic fermentation from acid hydrolyzed rice straw hydrolysate , 2011 .

[77]  Mohammad J. Taherzadeh,et al.  Alkaline pretreatment of spruce and birch to improve bioethanol and biogas production , 2010, BioResources.

[78]  Nasib Qureshi,et al.  Butanol production from wheat straw hydrolysate using Clostridium beijerinckii , 2007, Bioprocess and biosystems engineering.

[79]  S. Nygaard,et al.  The fungal symbiont of Acromyrmex leaf-cutting ants expresses the full spectrum of genes to degrade cellulose and other plant cell wall polysaccharides , 2013, BMC Genomics.

[80]  J. Lema,et al.  Fungal pretreatment of agricultural residues for bioethanol production , 2016 .

[81]  Ashok Pandey,et al.  Hydrolysis of pretreated rice straw by an enzyme cocktail comprising acidic xylanase from Aspergillus sp. for bioethanol production , 2016 .

[82]  E. Kovaleva,et al.  Lignin-associated metagene expression in a lignocellulose-digesting termite. , 2013, Insect biochemistry and molecular biology.

[83]  Y. Ju,et al.  Microbial community analysis in the termite gut and fungus comb of Odontotermes formosanus: the implication of Bacillus as mutualists. , 2012, FEMS microbiology ecology.

[84]  Kentaro Hayashi,et al.  Trace gas and particle emissions from open burning of three cereal crop residues: Increase in residue moistness enhances emissions of carbon monoxide, methane, and particulate organic carbon , 2014 .

[85]  Eric M. Adetutu,et al.  Enhanced Biological Straw Saccharification Through Coculturing of Lignocellulose-Degrading Microorganisms , 2015, Applied Biochemistry and Biotechnology.

[86]  Acetone-butanol-ethanol (ABE) production by Clostridium beijerinckii from wheat straw hydrolysates: efficient use of penta and hexa carbohydrates. , 2014, Bioresource technology.

[87]  L. Li,et al.  Screening of a fungus capable of powerful and selective delignification on wheat straw , 2008, Letters in applied microbiology.

[88]  R. Dinsdale,et al.  Enhanced biomethane potential from wheat straw by low temperature alkaline calcium hydroxide pre-treatment. , 2015, Bioresource technology.

[89]  Dinesh Goyal,et al.  Characterization of microwave-alkali-acid pre-treated rice straw for optimization of ethanol production via simultaneous saccharification and fermentation (SSF) , 2017 .

[90]  B. Young,et al.  Combination of fungal and physicochemical processes for lignocellulosic biomass pretreatment -- A review , 2016 .

[91]  H. W. Elbersen,et al.  Rice Straw and Wheat Straw - Potential feedstocks for the Biobased Economy , 2013 .

[92]  H. Pereira,et al.  Isolation and comparative characterization of a Björkman lignin from the saponified cork of Douglas-fir bark , 2006 .

[93]  Irini Angelidaki,et al.  Extreme thermophilic biohydrogen production from wheat straw hydrolysate using mixed culture fermentation: effect of reactor configuration. , 2010, Bioresource technology.

[94]  B. Pati,et al.  Bioconversion of rice straw to sugar using multizyme complex of fungal origin and subsequent production of bioethanol by mixed fermentation of Saccharomyces cerevisiae MTCC 173 and Zymomonas mobilis MTCC 2428 , 2013 .

[95]  M. Sharma,et al.  Review of process parameters for biodiesel production from different feedstocks , 2016 .

[96]  Panyue Zhang,et al.  Enhancement of corn stover hydrolysis with rumen fluid pretreatment at different solid contents: Effect, structural changes and enzymes participation , 2017 .

[97]  D. Jiménez,et al.  Different inocula produce distinctive microbial consortia with similar lignocellulose degradation capacity , 2016, Applied Microbiology and Biotechnology.

[98]  Mirjana Stajić,et al.  Lignin degradation by selected fungal species. , 2013, Bioresource technology.

[99]  K. Müller,et al.  Metagenomic analysis of microbial consortia enriched from compost: new insights into the role of Actinobacteria in lignocellulose decomposition , 2016, Biotechnology for Biofuels.

[100]  Narsi R. Bishnoi,et al.  Ethanol production from pretreated wheat straw hydrolyzate by Saccharomyces cerevisiae via sequential statistical optimization. , 2013 .

[101]  H. Saud,et al.  Development of compatible lignocellulolytic fungal consortium for rapid composting of rice straw , 2010 .

[102]  Clara Sargentini,et al.  Variability in chemical composition of straws. , 1991 .

[103]  F. Ein‐Mozaffari,et al.  Ozone pretreatment of wheat straw for enhanced biohydrogen production , 2013 .

[104]  P. Zhou,et al.  Isolation, identification and characterization of a straw degrading Streptomyces griseorubens JSD-1 , 2013 .

[105]  A. Kondo,et al.  Toward the complete utilization of rice straw: Methane fermentation and lignin recovery by a combinational process involving mechanical milling, supporting material and nanofiltration. , 2016, Bioresource technology.

[106]  Nasib Qureshi,et al.  Production of butanol (a biofuel) from agricultural residues: Part I – Use of barley straw hydrolysate☆ , 2010 .

[107]  A. R. Gonçalves,et al.  Combined process system for the production of bioethanol from sugarcane straw , 2014 .

[108]  A. Ragauskas,et al.  Comparative study of lignin characteristics from wheat straw obtained by soda-AQ and kraft pretreatment and effect on the following enzymatic hydrolysis process. , 2016, Bioresource technology.

[109]  D. Jiménez,et al.  Metataxonomic profiling and prediction of functional behaviour of wheat straw degrading microbial consortia , 2014, Biotechnology for Biofuels.

[110]  G. Beckham,et al.  Lignocellulose degradation mechanisms across the Tree of Life , 2015, Current opinion in chemical biology.

[111]  M. Faulstich,et al.  Solubilization of hemicellulose and lignin from wheat straw through microwave-assisted alkali treatment , 2012 .

[112]  Impact of delignification on the morphology and the reactivity of steam exploded wheat straw , 2016 .

[113]  Ram Chandra,et al.  Improving biodegradability and biogas production of wheat straw substrates using sodium hydroxide and hydrothermal pretreatments , 2012 .

[114]  N. Qureshi,et al.  Butanol production from wheat straw by simultaneous saccharification and fermentation using Clostridium beijerinckii: Part II—Fed-batch fermentation , 2008 .

[115]  T. Watanabe,et al.  Degradation of benzyl ether bonds of lignin by ruminal microbes. , 2000, FEMS microbiology letters.

[116]  J. Tomei,et al.  Food versus fuel? Going beyond biofuels , 2016 .

[117]  A. Chang,et al.  Screening of fungi capable of highly selective degradation of lignin in rice straw , 2012 .

[118]  P. Soininen,et al.  Enhanced sugar production from pretreated barley straw by additive xylanase and surfactants in enzymatic hydrolysis for acetone-butanol-ethanol fermentation. , 2015, Bioresource technology.

[119]  G. Jones,et al.  Physico-chemical characterization of different alcoholsoluble lignins from rice straw , 2012 .

[120]  S. Minaei,et al.  Development of a method for biohydrogen production from wheat straw by dark fermentation , 2011 .

[121]  Alison Mohr,et al.  Lessons from first generation biofuels and implications for the sustainability appraisal of second generation biofuels☆ , 2013, Energy Policy.

[122]  R. C. Kuhad,et al.  Degradation and selective ligninolysis of wheat straw and banana stem for an efficient bioethanol production using fungal and chemical pretreatment , 2012, 3 Biotech.

[123]  J. P. Steyer,et al.  Morphological structures of wheat straw strongly impacts its anaerobic digestion. , 2014 .

[124]  M. Ballesteros,et al.  Bioethanol production from wheat straw by the thermotolerant yeast Kluyveromyces marxianus CECT 10875 in a simultaneous saccharification and fermentation fed-batch process , 2009 .

[125]  M. Sriariyanun,et al.  Enhancing enzymatic hydrolysis and biogas production from rice straw by pretreatment with organic acids , 2016 .

[126]  L. Nain,et al.  Streptomyces griseorubens mediated delignification of paddy straw for improved enzymatic saccharification yields. , 2013, Bioresource technology.

[127]  Renu Singh,et al.  Environmental sustainability of bioethanol production from rice straw in India: A review , 2016 .

[128]  R. R. Vázquez,et al.  Enhancement of ligninolytic enzyme activities in a Trametes maxima–Paecilomyces carneus co-culture: Key factors revealed after screening using a Plackett–Burman experimental design , 2014 .

[129]  Kristin Seyboth,et al.  Renewable Energy Sources and Climate Change Mitigation: Reviewers of the IPCC Special Report , 2011 .

[130]  J. O. Baker,et al.  Tracking dynamics of plant biomass composting by changes in substrate structure, microbial community, and enzyme activity , 2012, Biotechnology for Biofuels.

[131]  R. Sun,et al.  Evaluation of the two-step treatment with ionic liquids and alkali for enhancing enzymatic hydrolysis of Eucalyptus: chemical and anatomical changes , 2016, Biotechnology for Biofuels.

[132]  Nibedita Sarkar,et al.  Bioethanol production from agricultural wastes: An overview , 2012 .

[133]  Ken Tokuyasu,et al.  A novel lime pretreatment for subsequent bioethanol production from rice straw--calcium capturing by carbonation (CaCCO) process. , 2010, Bioresource technology.

[134]  J. Mo,et al.  PHYSIOCHEMICAL LIGNOCELLULOSE MODIFICATION BY THE FORMOSAN SUBTERRANEAN TERMITE COPTOTERMES FORMOSANUS SHIRAKI (ISOPTERA: RHINOTERMITIDAE) AND ITS POTENTIAL USES IN THE PRODUCTION OF BIOFUELS , 2012 .

[135]  W. Liao,et al.  Bioethanol production using genetically modified and mutant wheat and barley straws , 2011 .

[136]  Heather D. Coleman,et al.  Effects on Lignin Structure of Coumarate 3-Hydroxylase Downregulation in Poplar , 2012, BioEnergy Research.

[137]  Yebo Li,et al.  Pretreatment of lignocellulosic biomass for enhanced biogas production. , 2014 .

[138]  G. Suen,et al.  Microbial Community Structure of Leaf-Cutter Ant Fungus Gardens and Refuse Dumps , 2010, PloS one.

[139]  V. Elisashvili,et al.  Lignocellulolytic activity of Coniophora puteana and Trametes versicolor in fermentation of wheat bran and decay of hydrothermally modified hardwoods , 2014 .

[140]  V. L. Papinutti,et al.  Lignocellulolytic enzymes from Fomes sclerodermeus growing in solid-state fermentation. , 2007 .

[141]  O. Derkacheva.  Estimation of Aromatic Structure Contents in Hardwood Lignins from IR Absorption Spectra , 2013 .

[142]  T. Filley,et al.  Lignocellulose modifications by brown rot fungi and their effects, as pretreatments, on cellulolysis. , 2012, Bioresource technology.

[143]  Nuruddin,et al.  Extraction and characterization of lignin from different biomass resources , 2015 .

[144]  Tao Zhang,et al.  Valorization of Lignin to Simple Phenolic Compounds over Tungsten Carbide: Impact of Lignin Structure. , 2017, ChemSusChem.

[145]  Héctor A. Ruiz,et al.  Bioethanol production from hydrothermal pretreated wheat straw by a flocculating Saccharomyces cerevisiae strain – Effect of process conditions , 2012 .

[146]  Sun Jianfeng,et al.  An estimation of CO2 emission via agricultural crop residue open field burning in China from 1996 to 2013 , 2016 .

[147]  John Ralph,et al.  Lignin Biosynthesis and Structure1 , 2010, Plant Physiology.

[148]  Sachin Kumar,et al.  Importance of chemical pretreatment for bioconversion of lignocellulosic biomass , 2014 .

[149]  Rajeev K Sukumaran,et al.  Biobutanol production from rice straw by a non acetone producing Clostridium sporogenes BE01. , 2013, Bioresource technology.

[150]  I. Roberto,et al.  Effect of nutrient supplementation on ethanol production in different strategies of saccharification and fermentation from acid pretreated rice straw , 2015 .

[151]  Hamid Zilouei,et al.  Organosolv pretreatment of rice straw for efficient acetone, butanol, and ethanol production. , 2014, Bioresource technology.