@article{ansanay_kolar_sharma-shivappa_cheng_arellano_2021, title={Pretreatment of Switchgrass for Production of Glucose via Sulfonic Acid-Impregnated Activated Carbon}, volume={9}, ISSN={["2227-9717"]}, DOI={10.3390/pr9030504}, abstractNote={In the present research, activated carbon-supported sulfonic acid catalysts were synthesized and tested as pretreatment agents for the conversion of switchgrass into glucose. The catalysts were synthesized by reacting sulfuric acid, methanesulfonic acid, and p-toluenesulfonic acid with activated carbon. The characterization of catalysts suggested an increase in surface acidities, while surface area and pore volumes decreased because of sulfonation. Batch experiments were performed in 125 mL serum bottles to investigate the effects of temperature (30, 60, and 90 °C), reaction time (90 and 120 min) on the yields of glucose. Enzymatic hydrolysis of pretreated switchgrass using Ctec2 yielded up to 57.13% glucose. Durability tests indicated that sulfonic solid-impregnated carbon catalysts were able to maintain activity even after three cycles. From the results obtained, the solid acid catalysts appear to serve as effective pretreatment agents and can potentially reduce the use of conventional liquid acids and bases in biomass-into-biofuel production.}, number={3}, journal={PROCESSES}, author={Ansanay, Yane and Kolar, Praveen and Sharma-Shivappa, Ratna and Cheng, Jay and Arellano, Consuelo}, year={2021}, month={Mar} } @article{jung_savithri_sharma-shivappa_kolar_2020, title={Effect of Sodium Hydroxide Pretreatment on Lignin Monomeric Components of Miscanthus x giganteus and Enzymatic Hydrolysis}, volume={11}, ISSN={["1877-265X"]}, DOI={10.1007/s12649-019-00859-8}, number={11}, journal={WASTE AND BIOMASS VALORIZATION}, author={Jung, Woochul and Savithri, Dhanalekshmi and Sharma-Shivappa, Ratna and Kolar, Praveen}, year={2020}, month={Nov}, pages={5891–5900} } @article{jung_sharma-shivappa_park_kolar_2020, title={Effect of cellulolytic enzyme binding on lignin isolated from alkali and acid pretreated switchgrass on enzymatic hydrolysis}, volume={10}, ISSN={["2190-5738"]}, DOI={10.1007/s13205-019-1978-z}, abstractNote={In this research, the binding of cellulolytic enzymes in Cellic® CTec2 on six lignin isolates obtained from alkali (0.5, 1.0, and 1.5% NaOH at 121 °C for 30 min) and acid (1, 2, and 3% H2SO4 at 121 °C for 60 min) pretreated switchgrass was investigated. Briefly, the hydrolysis of cellobiose and Avicel with and without (control) lignin isolates was performed via CTec2 (5 and 10 FPU g−1 carbohydrate) to determine whether the presence of lignin and binding of cellulolytic enzymes to the isolated lignin can affect the sugar production using three carbohydrate-lignin loadings, namely, 0.5:0.25, 0.5:0.5, and 0.5:1.0% (wv−1). Based on SDS-PAGE results, β-glucosidase (BG) was significantly bound to all lignin isolates. Some enzymes in CTec2 presumed to be cellobiohydrolases, endo-1,4-β-glucanases, and xylanase, were also observed to partially bind to the lignin isolates. Up to 0.97 g glucose g−1 cellobiose was produced via hydrolysis (72 h and pH 4.8) with CTec2 (5 and 10 FPU g−1 carbohydrate). Similarly, up to 0.23 and 0.46 g glucose g−1 Avicel were produced via hydrolysis (72 h and pH 4.8) with 5 and 10 FPU g−1 carbohydrate, respectively. Results indicated that the addition of lignin isolates during cellobiose and Avicel hydrolysis did not significantly (p > 0.05) reduce glucose production regardless of type and amount of lignin isolate. Hence, even though BG was significantly bound to lignin isolates, it could maintain its functionality as a biological catalyst in this study.}, number={1}, journal={3 BIOTECH}, author={Jung, Woochul and Sharma-Shivappa, Ratna and Park, Sunkyu and Kolar, Praveen}, year={2020}, month={Jan} } @article{edmunds_peralta_sharma-shivappa_kelley_chiang_miller_giles_sykes_deoppke_gjersing_et al._2020, title={Fungal Pretreatment and Enzymatic Hydrolysis of Genetically-modified Populus trichocarpa}, volume={15}, ISSN={["1930-2126"]}, DOI={10.15376/biores.15.3.6488-6505}, abstractNote={Fungal pretreatment of Populus trichocarpa wood genetically modified to reduce lignin and alter lignin chemistry is investigated for its effectiveness as an alternative to common pretreatment methods. The goal of this work is to improve biomass utilization for biofuel and biochemical applications by increasing sugar release. Sugar release after enzymatic hydrolysis was measured after various biomass pretreatments (including wood-rot fungus, hot water, and dilute acid). In the wildtype, and in constructs downregulated in PAL, 4CL, and C3H, the fungal pretreatment resulted in substantial improvements in sugar yields, up to 2.4-fold increase in glucose yield and 6-fold increase in xylose yield after enzymatic hydrolysis compared to the unpretreated control. However, the effects of fungal pretreatment were inconsistent, and in genetic lines down-regulated in 4CL, CCoAOMT, CAld5H, and C3H, fungal pretreatment yielded similar or decreased sugar release after enzymatic hydrolysis.}, number={3}, journal={BIORESOURCES}, author={Edmunds, Charles W. and Peralta, Perry and Sharma-Shivappa, Ratna R. and Kelley, Stephen S. and Chiang, Vincent L. and Miller, Zachary D. and Giles, Richard L. and Sykes, Robert W. and Deoppke, Crissa and Gjersing, Erica and et al.}, year={2020}, month={Aug}, pages={6488–6505} } @article{jung_sharma-shivappa_kolar_2019, title={Effect of Enzyme Interaction with Lignin Isolated from Pretreated Miscanthus x giganteus on Cellulolytic Efficiency}, volume={7}, ISSN={["2227-9717"]}, DOI={10.3390/pr7100755}, abstractNote={The effect of binding between the lignin isolates from an alkali (NaOH)– and an acid (H2SO4)– pretreated Miscanthus and cellulolytic enzymes in Cellic® CTec2 was investigated. Additonally, cellobiose and Avicel were enzymatically hydrolyzed with and without lignin isolates to study how enzyme binding onto lignin affects its conversion to glucose. Three carbohydrate–lignin loadings (0.5:0.25, 0.5:0.5, and 0.5:1.0% (w/v)) were employed. The results indicated that β-glucosidase (BG) had a strong tendency to bind to all lignin isolates. The overall tendency of enzyme binding onto lignin isolate was similar regardless of pretreatment chemical concentration. Though enzyme binding onto lignin isolates was observed, hydrolysis in the presence of these isolates did not have a significant (p > 0.05) impact on glucose production from cellobiose and Avicel. Cellobiose to glucose conversion of 99% was achieved via hydrolysis at both 5 and 10 FPU/g carbohydrate. Hydrolysis of Avicel with 5 and 10 FPU/g CTec2 resulted in 29.3 and 47.7% conversion to glucose, respectively.}, number={10}, journal={PROCESSES}, author={Jung, Woochul and Sharma-Shivappa, Ratna and Kolar, Praveen}, year={2019}, month={Oct} } @article{jung_savithri_sharma-shivappa_kolar_2018, title={Changes in Lignin Chemistry of Switchgrass due to Delignification by Sodium Hydroxide Pretreatment}, volume={11}, ISSN={["1996-1073"]}, DOI={10.3390/en11020376}, abstractNote={Switchgrass was pretreated with sodium hydroxide (NaOH) at various concentrations and pretreatment times to investigate how delignification caused by NaOH affects its lignin chemistry. NaOH resulted in significant delignification ranging from 44.0 to 84.6% depending on pretreatment intensity. While there was no significant glucan loss due to NaOH pretreatment, higher NaOH concentrations removed xylan by up to 28.3%. Nitrobenzene oxidation (NBO) was used to study changes in lignin chemistry, and indicated that at higher NaOH concentrations, the amount of 4-hydroxygenzaldehyde (Hy) degraded from p -hydroxyphenyl propanol (H) lignin units was significantly reduced ( p 0.05) change with 15 min pretreatment, but it increased to 0.75 and 0.72, respectively, with 30 and 60 min pretreatments ( p 0.05) change S/G ratio, but H/G ratio (=0.48 raw switchgrass) decreased significantly to 0.14 regardless of pretreatment times. Overall, the H unit was found to be more susceptible to NaOH than S and G unit monolignols. Though changes in lignin chemistry due to NaOH concentration were observed, their impact on cellulolytic enzyme action during hydrolysis could not be fully understood. Further studies on lignin isolation may help to determine how these changes in lignin chemistry by NaOH impact cellulolytic enzymes.}, number={2}, journal={ENERGIES}, author={Jung, Woochul and Savithri, Dhanalekshmi and Sharma-Shivappa, Ratna and Kolar, Praveen}, year={2018}, month={Feb} } @article{liu_yuan_sharma-shivappa_zanten_2017, title={Antioxidant activity of phlorotannins from brown algae}, volume={10}, ISSN={["1934-6352"]}, DOI={10.25165/j.ijabe.20171006.2854}, abstractNote={The antioxidant activity of the phlorotannins extracted from five marine algae species (Saccharina latissima, Alaria esculenta, Laminaria digitata, Fucus vesiculosus and Ascophyllum nodosum) was studied. Three phlorotannin groups, including soluble, membrane-bound, and extracted membrane-bound phlorotannins obtained by two solvent extraction methods were investigated for their DPPH radical scavenging activity. F. vesiculosus and A. nodosum showed the highest phlorotannin yield (14.83 mg-extract/g-algae and 12.80 mg-extract/g-algae, respectively) among the five algae species. Their soluble phlorophannin (SP), membrane-bound phlorotannin (MP) and extracted membrane-bound phlorotannin (eMP) extracts all showed equal or greater DPPH radical scavenging activity than the commercial antioxidants of butylated hydroxytoluene and ascorbic acid. The antioxidant potential that combines phlorotannin yield and antioxidant activity of the MP extracts of F. vesiculosus and A. nodosum (5890 mL/g and 5278 mL/g algae, respectively) were higher than those of SP and eMP, suggesting that the MPs of F. vesiculosus and A. nodosum had great potential to be used as antioxidants. Different extraction methods also showed significantly different effects on the antioxidant activity of the phlorotannin extracts. Keywords: brown algae, phlorotannin, antioxidant activity, antioxidant, bioseparation, polyphenol, solvent extraction methods DOI: 10.25165/j.ijabe.20171006.2854 Citation: Liu X, Yuan W Q, Sharma-Shivappa R, van Zanten J. Antioxidant activity of phlorotannins from brown algae. Int J Agric & Biol Eng, 2017; 10(6): 184–191.}, number={6}, journal={INTERNATIONAL JOURNAL OF AGRICULTURAL AND BIOLOGICAL ENGINEERING}, author={Liu, Xin and Yuan, Wenqiao and Sharma-Shivappa, Ratna and Zanten, John}, year={2017}, month={Nov}, pages={184–191} } @article{das_kolar_sharma-shivappa_classen_osborne_2017, title={Catalytic Valorization of Lignin Using Niobium Oxide}, volume={8}, ISSN={["1877-265X"]}, DOI={10.1007/s12649-016-9717-8}, number={8}, journal={WASTE AND BIOMASS VALORIZATION}, author={Das, Lalitendu and Kolar, Praveen and Sharma-Shivappa, Ratna and Classen, John J. and Osborne, Jason A.}, year={2017}, month={Dec}, pages={2673–2680} } @article{edmunds_peralta_kelley_chiang_sharma-shivappa_davis_harman-ware_sykes_gjersing_cunningham_et al._2017, title={Characterization and enzymatic hydrolysis of wood from transgenic Pinus taeda engineered with syringyl lignin or reduced lignin content}, volume={24}, ISSN={["1572-882X"]}, DOI={10.1007/s10570-017-1231-z}, abstractNote={Softwood is an abundant resource; however, currently its utilization for bioconversion to obtain platform sugars is limited. Pinus taeda trees which were genetically modified to either produce S lignin or to decrease lignin content were characterized with a suite of analytic techniques. Syringyl lignin was visualized in the secondary xylem of one genetic line with Mäule staining. Solid-state nuclear magnetic resonance identified the S lignin units were coupled into the lignin through β-O-4 linkages, and thioacidolysis measured approximately 13% S lignin content in the same sample. Reductions of the lignin of as much as 33% were observed in the transgenics. To better understand how these modifications affect bioconversion, their amenability to hot water and dilute acid pretreatments and enzymatic hydrolysis was evaluated. Lignin reductions resulted in 1.9–3.2-fold increases in glucose release compared to the control. However, no apparent benefit was observed by S lignin incorporation at the concentrations reported in this study. These results highlight the potential for softwood cell wall properties to be improved for bioenergy/biochemical applications.}, number={4}, journal={CELLULOSE}, author={Edmunds, Charles W. and Peralta, Perry and Kelley, Stephen S. and Chiang, Vincent L. and Sharma-Shivappa, Ratna R. and Davis, Mark F. and Harman-Ware, Anne E. and Sykes, Robert W. and Gjersing, Erica and Cunningham, Michael W. and et al.}, year={2017}, month={Apr}, pages={1901–1914} } @article{ansanay_kolar_sharma-shivappa_cheng_park_arellano_2017, title={Pre-treatment of biomasses using magnetised sulfonic acid catalysts}, volume={48}, number={2}, journal={Journal of Agricultural Engineering}, author={Ansanay, Y. and Kolar, P. and Sharma-Shivappa, R. and Cheng, J. and Park, S. and Arellano, C.}, year={2017}, pages={117–122} } @article{liang_shah_classen_sharma-shivappa_2014, title={Drying temperature - duration impacts on moisture, carbon, and nitrogen losses from broiler litter}, volume={16}, number={4}, journal={Agricultural Engineering International: CIGR Journal}, author={Liang, Weizhen and Shah, Sanjay B. and Classen, John and Sharma-Shivappa, Ratna}, year={2014}, pages={16–23} } @article{shi_chinn_sharma-shivappa_2014, title={Interactions between fungal growth, substrate utilization, and enzyme production during solid substrate cultivation of Phanerochaete chrysosporium on cotton stalks}, volume={37}, ISSN={1615-7591 1615-7605}, url={http://dx.doi.org/10.1007/s00449-014-1224-3}, DOI={10.1007/s00449-014-1224-3}, abstractNote={Fungal pretreatment, using lignin-degrading microorganisms to improve lignocellulosic feedstocks with minimal energy input, is a potential alternative to physiochemical pretreatment methods. Identifying the kinetics for fungal pretreatment during solid substrate cultivation is needed to help establish the processing conditions for effective scale up of this technology. In this study, a set of mathematical models were proposed for describing the interactions between holocellulose consumption, lignin degradation, cellulase, ligninolytic enzyme, and the growth of Phanerochaete chrysosporium during a 14 day fungal pretreatment process. Model parameters were estimated and validated by the System Biology Toolbox in MatLab. Developed models provided sufficiently accurate predictions for fungal growth (R (2) = 0.97), holocellulose consumption (R (2) = 0.97), lignin degradation (R (2) = 0.93) and ligninolytic enzyme production (R (2) = 0.92), and fair prediction for cellulase production (R (2) = 0.61). The models provide valuable information for understanding the interactive mechanisms in biological systems as well as for fungal pretreatment process scale up and improvement.}, number={12}, journal={Bioprocess and Biosystems Engineering}, publisher={Springer Science and Business Media LLC}, author={Shi, Jian and Chinn, Mari S. and Sharma-Shivappa, Ratna R.}, year={2014}, month={Jun}, pages={2463–2473} } @article{ansanay_kolar_sharma-shivappa_cheng_2014, title={Niobium oxide catalyst for delignification of switchgrass for fermentable sugar production}, volume={52}, ISSN={["1872-633X"]}, DOI={10.1016/j.indcrop.2013.11.044}, abstractNote={In this research, niobium oxide, a solid acid catalyst was evaluated as a pretreatment agent for delignification of Alamo switchgrass. The objectives were to determine the effects of temperature, catalyst loading, and pretreatment time on delignification and enzymatic hydrolysis of switchgrass and evaluate reusability of the catalyst. Batch experiments were performed using a Box–Behnken statistical model to study the effects of temperature, pretreatment time, and catalyst loading followed by hydrolysis using Cellic®Ctec2 (Novozymes). Niobium oxide was able to reduce total lignin concentrations up to 44.6 ± 0.97%. Hydrolysis experiments performed for 72 and 168 h (7% enzyme loading) indicated that a maximum glucose yield of 0.169 g g−1 (59.94% conversion)–0.196 g g−1 (77.51% conversion) was obtained. Catalyst reusability studies suggested that niobium oxide was able to pretreat four separate batches of switchgrass without losing activity. Niobium oxide is expected to serve as a reusable pretreatment catalyst and make ethanol production inexpensive and environmentally friendly.}, journal={INDUSTRIAL CROPS AND PRODUCTS}, author={Ansanay, Yane and Kolar, Praveen and Sharma-Shivappa, Ratna R. and Cheng, Jay J.}, year={2014}, month={Jan}, pages={790–795} } @article{liang_classen_shah_sharma-shivappa_2013, title={Ammonia Fate and Transport Mechanisms in Broiler Litter}, volume={225}, ISSN={0049-6979 1573-2932}, url={http://dx.doi.org/10.1007/s11270-013-1812-x}, DOI={10.1007/s11270-013-1812-x}, number={1}, journal={Water, Air, & Soil Pollution}, publisher={Springer Science and Business Media LLC}, author={Liang, Wei-zhen and Classen, John J. and Shah, Sanjay B. and Sharma-Shivappa, Ratna}, year={2013}, month={Dec} } @article{panneerselvam_sharma-shivappa_kolar_clare_ranney_2013, title={Hydrolysis of ozone pretreated energy grasses for optimal fermentable sugar production}, volume={148}, ISSN={["1873-2976"]}, DOI={10.1016/j.biortech.2013.08.119}, abstractNote={Ozonated energy grass varieties were enzymatically hydrolyzed to establish process parameters for maximum fermentable sugar production. Conditions for ozonolysis were selected on the basis of maximum delignification and glucan retention after pretreatment. To study the effect of lignin degradation products generated during ozonolysis on cellulolytic enzymes, hydrolysis was carried out for washed and unwashed pretreated solids. Washing the solids significantly (p < 0.05) enhanced glucan conversion from 34.3% to 100% while delivering glucose yields of 146.2–431.9 mg/g biomass. Highest fermentable sugars were produced when grasses were ozonated for maximum delignification and washed solids were hydrolyzed using 0.1 g/g Cellic® CTec2. In a comparative study on alkaline pretreatment with 1% NaOH for 60 min, Saccharum arundinaceum exhibited the highest glucan conversion with maximum sugar production of 467.9 mg/g. Although ozonolysis is an effective and environmentally friendly technique for cellulosic sugar production, process optimization is needed to ascertain economic feasibility of the process.}, journal={BIORESOURCE TECHNOLOGY}, author={Panneerselvam, Anushadevi and Sharma-Shivappa, Ratna R. and Kolar, Praveen and Clare, Debra A. and Ranney, Thomas}, year={2013}, month={Nov}, pages={97–104} } @article{liang_shah_classen_sharma-shivappa_2013, title={Modeling Ammonium Adsorption on Broiler Litter and Cake}, volume={224}, ISSN={["0049-6979"]}, DOI={10.1007/s11270-012-1405-0}, number={2}, journal={WATER AIR AND SOIL POLLUTION}, author={Liang, Wei-zhen and Shah, Sanjay B. and Classen, John J. and Sharma-Shivappa, Ratna}, year={2013}, month={Feb} } @article{panneerselvam_sharma-shivappa_kolar_ranney_peretti_2013, title={Potential of ozonolysis as a pretreatment for energy grasses}, volume={148}, ISSN={["1873-2976"]}, DOI={10.1016/j.biortech.2013.08.129}, abstractNote={This study investigated the effect of ozonolysis on Miscanthus × giganteus, Miscanthus sinensis 'Gracillimus', Saccharum arundinaceum and Saccharum ravennae, collectively referred to as 'energy grasses'. Studies were conducted at three different ozone concentrations (40, 50 and 58 mg/l) using two ozone flow configurations - uni-directional and reversed flow. Pretreatment conditions for each variety were optimized based on lignin content and glucan recovery in ozonated solids. Results showed that ozonolysis was effective in removing up to 59.9% lignin without cellulose degradation. However, subsequent hydrolysis of pretreated solids with Cellic® CTec2 at 0.06 g/g raw biomass provided glucan conversion lower than untreated samples suggesting enzyme inhibition by lignin degradation products formed during ozonolysis. Future studies investigating hydrolysis efficiency of washed pretreated solids with higher enzyme loadings are therefore warranted to optimize the hydrolysis process and make it functionally feasible.}, journal={BIORESOURCE TECHNOLOGY}, author={Panneerselvam, Anushadevi and Sharma-Shivappa, Ratna R. and Kolar, Praveen and Ranney, Thomas and Peretti, Steven}, year={2013}, month={Nov}, pages={242–248} } @article{athalye_sharma-shivappa_peretti_kolar_davis_2013, title={Producing biodiesel from cottonseed oil using Rhizopus oryzae ATCC #34612 whole cell biocatalysts: Culture media and cultivation period optimization}, volume={17}, ISSN={0973-0826}, url={http://dx.doi.org/10.1016/J.ESD.2013.03.009}, DOI={10.1016/j.esd.2013.03.009}, abstractNote={The effect of culture medium composition and cultivation time on biodiesel production by Rhizopus oryzae ATCC #34612 whole cell catalysts, immobilized on novel rigid polyethylene biomass supports, was investigated. Supplementation of the medium with carbon sources led to higher lipase activity and increased the biomass immobilized on the BSPs. Statistical analysis indicates that a cultivation period of 72 h in a basal medium supplemented with both cottonseed oil and glucose is optimal for biodiesel production by R. oryzae, resulting in a fatty acid methyl ester (FAME) yield of 27.9 wt.% (228.2 g/L).}, number={4}, journal={Energy for Sustainable Development}, publisher={Elsevier BV}, author={Athalye, Sneha and Sharma-Shivappa, Ratna and Peretti, Steven and Kolar, Praveen and Davis, Jack P.}, year={2013}, month={Aug}, pages={331–336} } @article{wang_sharma-shivappa_olson_khan_2013, title={Production of polyhydroxybutyrate (PHB) by Alcaligenes latus using sugarbeet juice}, volume={43}, ISSN={["1872-633X"]}, DOI={10.1016/j.indcrop.2012.08.011}, abstractNote={The practicality of using sugarbeet juice as medium to grow Alcaligenes latus (ATCC 29714) for production of polyhydroxybutyrate (PHB), a biodegradable plastic, was explored in this study. Dilute sugarbeet juice, sugarbeet juice with partial and complete addition of nutrients other than sugar were used as culture media. Media with partial nutrient addition was shown to be optimal for PHB production, with final dry cell weight (DCW) 10.30 ± 1.01 g/L, PHB concentration 4.01 ± 0.95 g/L, PHB content 38.66 ± 7.28%, Yp/x (g PHB produced per g dry cell weight) 0.39 ± 0.07 and a maximum PHB productivity of 0.22 ± 0.01 g/L h. The melting temperature of PHB extracted from sugarbeet juice-grown cells supplemented with partial nutrients was measured to be 151.46 °C with crystallinity of 43.12% and the corresponding crystallinity temperature of 45.42 °C. Thermal degradation of extracted PHB occurred from 255.14 to 283.69 °C with the degradation peak at 273.86 °C.}, journal={INDUSTRIAL CROPS AND PRODUCTS}, author={Wang, Bingqing and Sharma-Shivappa, Ratna R. and Olson, Jonathan W. and Khan, Saad A.}, year={2013}, month={May}, pages={802–811} } @article{jairam_kolar_sharma-shivappa_osborne_2013, title={Synthesis of solid acid catalyst from tobacco stalk for esterification of oleic acid}, volume={29}, number={3}, journal={Applied Engineering in Agriculture}, author={Jairam, S. and Kolar, P. and Sharma-Shivappa, R. S. and Osborne, J. A.}, year={2013}, pages={385–389} } @article{kaur_oberoi_bhargav_sharma-shivappa_dhaliwal_2012, title={Ethanol production from alkali- and ozone-treated cotton stalks using thermotolerant Pichia kudriavzevii HOP-1}, volume={37}, ISSN={["1872-633X"]}, DOI={10.1016/j.indcrop.2011.12.007}, abstractNote={In the present study, milled cotton stalks were subjected to alkali pretreatment with NaOH at 1–4% (w/v) concentrations at 121 °C for time ranging from 30 to 90 min. Ozone pretreatment was performed by passing 45 mg/L of ozone gas over 2 mm cotton stalks for 150 min at a flow rate of 0.37 L/min. The residual biomass from 4% alkali pretreatment for 60 min showed 46.6% lignin degradation accompanied by 83.2% increase in glucan content, compared with the untreated biomass. Hydrolysis of 4% alkali-treated and ozone-treated cotton stalks was conducted using enzyme combination of 20 filter paper cellulase units/gram dried substrate (FPU/g-ds), 45 IU/g-ds β-glucosidase and 15 IU/g-ds pectinase. Enzymatic hydrolysis of alkali-treated and ozone-treated biomass after 48 h resulted in 42.29 g/L glucose, 6.82 g/L xylose and 24.13 g/L glucose, 8.3 g/L xylose, respectively. About 99% of glucose was consumed in 24 h by Pichia kudriavzevii HOP-1 cells resulting in 19.82 g/L of ethanol from alkali-treated cotton stalks and 10.96 g/L of ethanol from ozone-treated cotton stalks. Simultaneous saccharification and fermentation of the alkali-treated cotton stalks after 12-h pre-hydrolysis resulted in ethanol concentration, ethanol yield on dry biomass basis and ethanol productivity of 19.48 g/L, 0.21 g/g and 0.41 g/L/h, respectively which holds promise for further scale-up studies. To the best of our knowledge, this is the first study employing SSF for ethanol production from cotton stalks.}, number={1}, journal={INDUSTRIAL CROPS AND PRODUCTS}, author={Kaur, Ujjal and Oberoi, Harinder Singh and Bhargav, Vinod Kumar and Sharma-Shivappa, Ratna and Dhaliwal, Sandeep Singh}, year={2012}, month={May}, pages={219–226} } @article{shi_sharma-shivappa_chinn_2012, title={Interactions between fungal growth, substrate utilization and enzyme production during shallow stationary cultivation of Phanerochaete chrysosporium on cotton stalks}, volume={51}, ISSN={["1879-0909"]}, DOI={10.1016/j.enzmictec.2012.03.006}, abstractNote={Microbial pretreatment of lignocellulosic feedstocks is an environment friendly alternative to physio-chemical pretreatment methods. A better understanding of the interactive fungal mechanisms in biological systems is essential for enhancing performance and facilitating scale-up and commercialization of this pretreatment technique. In this study, mathematical models were developed for describing cellulose and hemicellulose consumption, lignin degradation, cellulase and ligninolytic enzyme production and oxygen uptake associated with the growth of Phanerochaete chrysosporium during a 14-day shallow stationary submerged fungal pretreatment process on cotton stalks. Model parameters were estimated and validated by Statistics Toolbox in MatLab 7.1. Models yielded sufficiently accurate predictions for cellulose and hemicellulose consumption (R²=0.9772 and 0.9837), lignin degradation (R²=0.9879 and 0.8682) and ligninolytic enzyme production (R²=0. 8135 and 0.9693) under both 1-day and 3-day oxygen flushing conditions, respectively. The predictabilities for fungal growth (R²=0.6397 and 0.5750) and cellulase production (R²=0.0307 and 0.3046) for 1-day and 3-day oxygen flushing, respectively, and oxygen uptake (R²=0.5435) for 3-day oxygen flushing were limited.}, number={1}, journal={ENZYME AND MICROBIAL TECHNOLOGY}, author={Shi, Jian and Sharma-Shivappa, Ratna R. and Chinn, Mari S.}, year={2012}, month={Jun}, pages={1–8} } @article{jairam_kolar_sharma-shivappa_osborne_davis_2012, title={KI-impregnated oyster shell as a solid catalyst for soybean oil transesterification}, volume={104}, ISSN={["1873-2976"]}, DOI={10.1016/j.biortech.2011.10.039}, abstractNote={Research on inexpensive and green catalysts is needed for economical production of biodiesel. The goal of the research was to test KI-impregnated calcined oyster shell as a solid catalyst for transesterification of soybean oil. Specific objectives were to characterize KI-impregnated oyster shell, determine the effect of reaction variables and reaction kinetics. The catalyst was synthesized by impregnating KI on calcined oyster shells. X-ray diffraction analysis indicated the presence of portlandite and potassium iodide on the surface and a 31-fold increase in surface as a result of calcination and KI impregnation. Under the conditions tested, ideal reaction variables were 1 mmol g−1 for catalyst loading, 50 °C for temperature, 10:1 for methanol/oil, and 4 h for reaction time. The transesterification followed a first-order reaction (k = 0.4385 h−1). The option of using oyster shell for the production of transesterification catalysts could have economic benefits to the aquaculture industry in the US.}, journal={BIORESOURCE TECHNOLOGY}, author={Jairam, Suguna and Kolar, Praveen and Sharma-Shivappa, Ratna and Osborne, Jason A. and Davis, Jack P.}, year={2012}, month={Jan}, pages={329–335} } @article{sharma_palled_sharma-shivappa_osborne_2012, title={Potential of Potassium Hydroxide Pretreatment of Switchgrass for Fermentable Sugar Production}, volume={169}, ISSN={0273-2289 1559-0291}, url={http://dx.doi.org/10.1007/S12010-012-0009-X}, DOI={10.1007/s12010-012-0009-x}, abstractNote={Chemical pretreatment of lignocellulosic biomass has been extensively investigated for sugar generation and subsequent fuel production. Alkaline pretreatment has emerged as one of the popular chemical pretreatment methods, but most attempts thus far have utilized NaOH for the pretreatment process. This study aimed at investigating the potential of potassium hydroxide (KOH) as a viable alternative alkaline reagent for lignocellulosic pretreatment based on its different reactivity patterns compared to NaOH. Performer switchgrass was pretreated at KOH concentrations of 0.5-2% for varying treatment times of 6-48 h, 6-24 h, and 0.25-1 h at 21, 50, and 121 °C, respectively. The pretreatments resulted in the highest percent sugar retention of 99.26% at 0.5%, 21 °C, 12 h while delignification up to 55.4% was observed with 2% KOH, 121 °C, 1 h. Six pretreatment conditions were selected for subsequent enzymatic hydrolysis with Cellic CTec2® for sugar generation. The pretreatment condition of 0.5% KOH, 24 h, 21 °C was determined to be the most effective as it utilized the least amount of KOH while generating 582.4 mg sugar/g raw biomass for a corresponding percent carbohydrate conversion of 91.8%.}, number={3}, journal={Applied Biochemistry and Biotechnology}, publisher={Springer Science and Business Media LLC}, author={Sharma, Rajat and Palled, Vijaykumar and Sharma-Shivappa, Ratna R. and Osborne, Jason}, year={2012}, month={Dec}, pages={761–772} } @article{xu_chen_cheng_sharma-shivappa_burns_2011, title={Delignification of switchgrass cultivars for bioethanol production}, volume={6}, number={1}, journal={BioResources}, author={Xu, J. L. and Chen, Y. and Cheng, J. J. and Sharma-Shivappa, R. R. and Burns, J. C.}, year={2011}, pages={707–720} } @article{xu_wang_sharma-shivappa_cheng_2011, title={Enzymatic hydrolysis of switchgrass and coastal bermuda grass pretreated using different chemical methods}, volume={6}, number={3}, journal={BioResources}, author={Xu, J. L. and Wang, Z. Y. and Sharma-Shivappa, R. R. and Cheng, J. J.}, year={2011}, pages={2990–3003} } @article{chinn_sharma-shivappa_cotter_2011, title={Solvent extraction and quantification of capsaicinoids from Capsicum chinense}, volume={89}, ISSN={["0960-3085"]}, DOI={10.1016/j.fbp.2010.08.003}, abstractNote={Capsaicinoid extraction from peppers is typically performed using organic solvents, however, the extraction efficiencies can vary with peppers, their parts and pre-extraction processing. In the absence of in depth information on capsaicinoid extraction from habañero peppers, this work was undertaken to examine the processing parameters for solvent extraction of capsaicinoids from whole habañero peppers (Capsicum chinense) and their various parts. The effects of solvent type (ethanol, acetone and acetonitrile), pepper part(s) (seeds, shells), tissue preparation (freeze and oven drying), and time on capsaicinoid recovery (capsaicin and dihydrocapsaicin) were evaluated. Across all solvents, capsaicin yields were on average 16, 5 and 8 mg/g dry pepper part for seeds, shells and whole peppers, respectively. Dihydrocapsaicin yield ranged from 0.65 to 9.17 mg/g dry pepper depending on interaction between parts and preparation. Overall, higher yields of capsacinoids were obtained from oven-dried peppers using acetone as the solvent.}, number={C4}, journal={FOOD AND BIOPRODUCTS PROCESSING}, author={Chinn, Mari S. and Sharma-Shivappa, Ratna R. and Cotter, Jacqueline L.}, year={2011}, month={Oct}, pages={340–345} } @article{xu_cheng_sharma-shivappa_burns_2010, title={Lime pretreatment of switchgrass at mild temperatures for ethanol production}, volume={101}, ISSN={["1873-2976"]}, DOI={10.1016/j.biortech.2009.12.015}, abstractNote={To improve the enzymatic digestibility of switchgrass at mild temperatures, lime pretreatment of switchgrass was explored at 50 and 21 degrees Celsius, and compared with that at 121 degrees Celsius. The effects of residence time, lime loading, and biomass washing on the sugar production efficiency were investigated. Pretreatments were evaluated based on the yields of biomass-derived sugars in the subsequent enzymatic hydrolysis. Under the best pretreatment conditions (50 degrees Celsius, 24 h, 0.10 g Ca(OH)(2)/g raw biomass, and wash intensity of 100 ml water/g raw biomass), the yields of glucose, xylose, and total reducing sugars reached 239.6, 127.2, and 433.4 mg/g raw biomass, which were respectively 3.15, 5.78, and 3.61 times those of untreated biomass. The study on calcium-lignin bonding showed that calcium ions crosslinked lignin molecules under alkaline conditions, which substantially decreased lignin solubilization during pretreatment, but the resulting high lignin contents of the pretreated biomass did not compromise the improvement of enzymatic digestibility.}, number={8}, journal={BIORESOURCE TECHNOLOGY}, author={Xu, Jiele and Cheng, Jay J. and Sharma-Shivappa, Ratna R. and Burns, Joseph C.}, year={2010}, month={Apr}, pages={2900–2903} } @article{xu_cheng_sharma-shivappa_burns_2010, title={Sodium Hydroxide Pretreatment of Switchgrass for Ethanol Production}, volume={24}, ISSN={["1520-5029"]}, DOI={10.1021/ef9014718}, abstractNote={Lignocellulose-to-ethanol conversion is a promising technology to supplement corn-based ethanol production. However, the recalcitrant structure of lignocellulosic material is a major obstacle to the efficient conversion. To improve the enzymatic digestibility of switchgrass for the fermentable sugar production in hydrolysis, sodium hydroxide pretreatment of the biomass feedstock was investigated. At 121, 50, and 21 °C, raw switchgrass biomass at a solid/liquid ratio of 0.1 g/mL was pretreated, respectively, for 0.25−1, 1−48, and 1−96 h at different NaOH concentrations (0.5, 1.0, and 2.0%, w/v). Pretreatments were evaluated based on the yields of lignocellulose-derived sugars in the subsequent enzymatic hydrolysis. At the best pretreatment conditions (50 °C, 12 h, and 1.0% NaOH), the yield of total reducing sugars was 453.4 mg/g raw biomass, which was 3.78 times that of untreated biomass, and the glucan and xylan conversions reached 74.4 and 62.8%, respectively. Lignin reduction was closely related to the ...}, number={3}, journal={ENERGY & FUELS}, author={Xu, Jiele and Cheng, Jay J. and Sharma-Shivappa, Ratna R. and Burns, Joseph C.}, year={2010}, month={Mar}, pages={2113–2119} } @article{george_yang_wang_sharma-shivappa_tungate_2010, title={Suitability of Canola Residue for Cellulosic Ethanol Production}, volume={24}, ISSN={["1520-5029"]}, DOI={10.1021/ef1002155}, abstractNote={The acreage of winter canola in the Southeastern United States is presently limited but is expected to increase in the future as demand for biodiesel grows. The residue production of canola is known to be relatively high in comparison to other grain crops. Only the seed of canola is currently harvested and utilized, but if canola is to be grown more widely the crop residue could potentially be used for biofuel production. This proof of concept study investigated the value of canola crop residue as a feedstock for cellulosic ethanol production. The mean dry yield of residue for canola was found to be approximately 9 Mg/ha, which is higher than for other common winter crops produced in the Southeast. Cellulosic ethanol production from the residue was investigated through acid (H2SO4) and alkali (NaOH) pretreatment followed by enzymatic hydrolysis with cellulase and cellobiase and hexose fermentation with Saccharomyces cerevisiae. The ethanol yield from the biomass was relatively low, at around 95 L per dry ...}, number={8}, journal={ENERGY & FUELS}, author={George, Nicholas and Yang, Ying and Wang, Ziyu and Sharma-Shivappa, Ratna and Tungate, Kim}, year={2010}, month={Aug}, pages={4454–4458} } @article{yang_sharma-shivappa_burns_cheng_2009, title={Dilute Acid Pretreatment of Oven-dried Switchgrass Germplasms for Bioethanol Production}, volume={23}, ISSN={["1520-5029"]}, DOI={10.1021/ef900043z}, abstractNote={Bioethanol production potential of three oven-dried switchgrass germplasms (St6−1, St6−3E, and St6−3F) containing 26.65−29.28% glucan, 17.92−19.37% xylan, and 17.74−19.23% lignin (dry matter basis) was investigated. Evaluation of the effect of three acid concentrations (0.5, 1.0, and 1.5% w/v) and residence times (30, 45, and 60 min) on composition of all germplasms indicated significant hemicellulose solublization relying greatly on pretreatment intensity. No apparent delignification was observed during pretreatment. Pretreated samples with the least lignin content or greatest hemicellulose solubilization within each germplasm were selected for hydrolysis and fermentation. Enzymatic hydrolysis at cellulase activities of 0, 15, and 30 FPU (filter paper units)/g dry biomass indicated that addition of cellulase significantly improved glucan hydrolysis (P 0.05). Glucan-to-glucose conversion was enhanced by acid pretreatme...}, number={7}, journal={ENERGY & FUELS}, author={Yang, Ying and Sharma-Shivappa, Ratna and Burns, Joseph C. and Cheng, Jay J.}, year={2009}, month={Jul}, pages={3759–3766} } @article{shi_sharma-shivappa_chinn_howell_2009, title={Effect of microbial pretreatment on enzymatic hydrolysis and fermentation of cotton stalks for ethanol production}, volume={33}, ISSN={["1873-2909"]}, DOI={10.1016/j.biombioe.2008.04.016}, abstractNote={The potential of microbial pretreatment of cotton stalks by Phanerochaete chrysosporium to degrade lignin and facilitate fuel ethanol production was investigated under two culture conditions: submerged cultivation (SmC) and solid state (SSC) cultivation. Although microbial pretreatments showed significant lignin degradation (LD) (19.38% and 35.53% for SmC and SSC, respectively), a study on hydrolysis and fermentation of the microbial-pretreated cotton stalks showed no increase in cellulose conversion (10.98% and 3.04% for SmC and SSC pretreated samples, respectively) compared to untreated cotton stalks (17.93%). Solid state cultivation demonstrated better selectivity of 0.82 than 0.70 with submerged pretreatment. Washing of pretreated cotton stalks did not significantly increase cellulose conversion. However, heating and washing remarkably improved (P<0.05) cellulose conversion to 14.94% and 17.81% for SmC and SSC 14 day pretreatment, respectively. Ethanol yields, up to 0.027 g ethanol g−1 initial cotton stalks, were low for all untreated and pretreated samples mainly due to the low cellulose conversion. Although potential and some critical aspects of fungal pretreatment using P. chrysosporium have been explored in this study, additional investigation is still required especially to improve the selectivity for preferential LD and to optimize hydrolysis efficiency. The mechanism of catalytic binding of cellulolytic enzymes to cotton stalks as affected by the presence of fungal mycelia also warrants further study.}, number={1}, journal={BIOMASS & BIOENERGY}, author={Shi, Jian and Sharma-Shivappa, Ratna R. and Chinn, Mari and Howell, Noura}, year={2009}, month={Jan}, pages={88–96} } @article{shi_sharma-shivappa_chinn_2009, title={Microbial pretreatment of cotton stalks by submerged cultivation of Phanerochaete chrysosporium}, volume={100}, ISSN={["1873-2976"]}, DOI={10.1016/j.biortech.2008.10.060}, abstractNote={This study used the fungus, Phanerochaete chrysosporium, to pretreat cotton stalks with two methods, shallow stationary and agitated cultivation, at three supplemental salt concentrations. Pretreatment efficiencies were compared by evaluating lignin degradation, solid recovery and carbohydrate availability over a 14-day period. Shallow stationary cultivation with no salts gave 20.7% lignin degradation along with 76.3% solid recovery and 29.0% carbohydrate availability. The highest lignin degradation of 33.9% at a corresponding solid recovery and carbohydrate availability of 67.8% and 18.4%, respectively, was obtained through agitated cultivation with Modified NREL salts. Cultivation beyond 10 days did not significantly increase lignin degradation during 14 days of pretreatment. Manganese addition during shallow stationary and agitated cultivation resulted in higher solid recoveries of over 80% but lower lignin degradation. Although agitated cultivation resulted in better delignification, results indicate that pretreatment under submerged shallow stationary conditions provides a better balance between lignin degradation and carbohydrate availability.}, number={19}, journal={BIORESOURCE TECHNOLOGY}, author={Shi, Jian and Sharma-Shivappa, Ratna R. and Chinn, Mari S.}, year={2009}, month={Oct}, pages={4388–4395} } @article{yang_sharma-shivappa_burns_cheng_2009, title={Saccharification and Fermentation of Dilute-Acid-Pretreated Freeze-Dried Switchgrass}, volume={23}, ISSN={["1520-5029"]}, DOI={10.1021/ef9003335}, abstractNote={This study investigated the potential of three freeze-dried switchgrass germplasms (St6-1, St6-3E, and St6-3F) as whole plants or their stems and leaves for bioethanol production. Whole switchgrass germplasms contained 24.34−30.95% glucan, 14.68−18.58% xylan, and 17.39−19.46% lignin. Switchgrass samples were pretreated with dilute sulfuric acid at concentrations of 0.5, 1.0, or 1.5% (w/v) for 30, 45, or 60 min at 121 °C and 15 psi. Although lignin degradation was limited, over 80% hemicellulose solublization was observed, especially in leaf samples, and the removal could be enhanced by increasing the pretreatment intensity through acid concentration and treatment time adjustment. Within each germplasm, pretreated samples with the least lignin content or greatest percent hemicellulose (xylan and arabinan) solublization were hydrolyzed enzymatically by cellulase at 0, 15, or 30 filter paper units (FPU)/g of dry biomass supplemented with cellobiase. Although the addition of cellulase greatly improved cellulo...}, number={11}, journal={ENERGY & FUELS}, author={Yang, Ying and Sharma-Shivappa, Ratna R. and Burns, Joseph C. and Cheng, Jay}, year={2009}, month={Nov}, pages={5626–5635} } @inproceedings{yang_sharma_burns_cheng_2008, title={Hydrolysis and fermentation of new switchgrass germplasm for bioethanol production}, volume={083799}, booktitle={Proceedings of the ASABE Annual International Meeting (Providence, Rhode Island)}, author={Yang, Y. and Sharma, R. R. and Burns, J. C. and Cheng, J. J.}, year={2008} } @inproceedings{xu_cheng_sharma-shivappa_burns_2008, title={Lime pretreatment of switchgrass for bioethanol production}, volume={083998}, DOI={10.13031/2013.24815}, abstractNote={Lignocellulose-to-ethanol conversion is a promising technology to supplement corn-based ethanol production. To improve the enzymatic digestibility of lignocellulosic materials, pretreatment is necessary as it alters the structure of lignocellulosic matrix, thereby making the cellulose more accessible to cellulase enzymes during hydrolysis. In this research, switchgrass was used as lignocellulosic feedstock and lime was used as pretreatment agent to study the impact of lime loading, residence time and temperature on the reducing sugar yield of biomass after pretreatment. The results showed that lime pretreatment could effectively improve the digestibility of switchgrass at both high temperature and low temperature. At 121oC, increasing lime loading or extending residence time didn’t necessarily favor the improvement of biomass digestibility. 15 min pretreatment with the lime loading of 0.10 g/g raw biomass was recommended. At 50oC, longer residence times were needed while the lime requirement didn’t change. 24 h pretreatment with the lime loading of 0.10 g/g raw biomass was recommended. Using the recommended conditions, the reducing sugar yields of pretreated biomass were over 4 times that of unpretreated biomass. The research also showed that lime pretreatment was promising at even lower temperatures. At ambient temperature, the total reducing sugar yield from raw biomass reached 392 mg/g raw biomass after 24 h lime pretreatment, only 8% lower than that obtained under the recommended condition at 121oC or 50oC.}, booktitle={Proceedings of the ASABE Annual International Meeting (Providence, Rhode Island)}, author={Xu, J. and Cheng, Jay and Sharma-Shivappa, R. R. and Burns, J. C.}, year={2008} } @article{shi_chinn_sharma-shivappa_2008, title={Microbial pretreatment of cotton stalks by solid state cultivation of Phanerochaete chrysosporium}, volume={99}, ISSN={["1873-2976"]}, DOI={10.1016/j.biortech.2007.11.069}, abstractNote={White rot fungi degrade lignin and have biotechnological applications in conversion of lignocellulose to valuable products. Pretreatment is an important processing step to increase the accessibility of cellulosic material in plant biomass, impacting efficiency of subsequent hydrolysis and fermentation. This study investigated microbial pretreatment of cotton stalks by solid state cultivation (SSC) using Phanerochaete chrysosporium to facilitate the conversion into ethanol. The effects of substrate moisture content (M.C.; 65%, 75% and 80% wet-basis), inorganic salt concentration (no salts, modified salts without Mn(2+), modified salts with Mn(2+)) and culture time (0-14 days) on lignin degradation (LD), solids recovery (SR) and availability of carbohydrates (AOC) were examined. Moisture content significantly affected lignin degradation, with 75% and 80% M.C. degrading approximately 6% more lignin than 65% M.C. after 14 days. Within the same moisture content, treatments supplemented with salts were not statistically different than those without salts for LD and AOC. Within the 14day pretreatment, additional time resulted in greater lignin degradation, but indicated a decrease in SR and AOC. Considering cost, solid state cultivation at 75% M.C. without salts was the most preferable pretreatment resulting in 27.6% lignin degradation, 71.1% solids recovery and 41.6% availability of carbohydrates over a period of 14 days. Microbial pretreatment by solid state cultivation has the potential to be a low cost, environmentally friendly alternative to chemical approaches. Moisture relationships will be significant to the design of an effective microbial pretreatment process using SSC technology.}, number={14}, journal={BIORESOURCE TECHNOLOGY}, author={Shi, Jian and Chinn, Mari S. and Sharma-Shivappa, Ratna R.}, year={2008}, month={Sep}, pages={6556–6564} } @article{sharma-shivappa_chen_2008, title={conversion of cotton wastes to bioenergy and value-added products}, volume={51}, DOI={10.13031/2013.25377}, abstractNote={Cotton accounts for nearly 40% of global fiber production. While approximately 80 countries worldwide produce cotton, the U.S., China, and India together provide over half the world's cotton. High cotton production is accompanied by generation of tons of cotton waste each year. Large amounts of residue from the field and gins results in not only environmental problems due to disposal issues and cotton diseases and pests, but also difficulties in cultivation due to slow decomposition in the soil. Development of economical and efficient methods for utilizing and/or disposing of cotton waste have been investigated for years, but scale-up and marketing issues need to be resolved. Cotton waste can be used as an energy source through briquetting, pyrolysis, and anaerobic digestion. Studies suggest that composition of cotton waste is similar to other lignocellulosic feedstocks, and it has the potential to be used for bioethanol production. However, proper pretreatment strategies need to be developed to reduce lignin (comprising approximately 30%). Cotton waste can also be processed into industrial products such as animal feed and bedding, soil amendment, and substrate for vegetative growth through various treatments. Enzyme production through utilization of cotton waste as a carbon source is another potential application. A review of the various conversion processes suggests that although cotton waste is suitable for the production of a variety of products, in-depth investigation at the pilot scale is essential to determine process efficacy and economic feasibility.}, number={6}, journal={Transactions of the ASABE}, author={Sharma-Shivappa, R. R. and Chen, Y.}, year={2008}, pages={2239–2246} } @article{silverstein_chen_sharma-shivappa_boyette_osborne_2007, title={A comparison of chemical pretreatment methods for improving saccharification of cotton stalks}, volume={98}, ISSN={["1873-2976"]}, DOI={10.1016/j.biortech.2006.10.022}, abstractNote={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