Optimization of Enzymatic Hydrolysis of Corn Stover for Improved Ethanol Production

Zambare, Vasudeo; Christopher, Lew P.

doi:10.1260/0144-5987.30.2.193

Cited by 10 publications

(6 citation statements)

References 37 publications

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“…Table 2 presents the results of different S. cerevisiae fermentations using the same microbial strain, pretreatment, and/or feedstock as in the present work. Zambare et al (2011 and used S. cerevisiae ATCC 24860 and an SHF configuration for ethanol production from Spartina pectinata and corn stover, respectively [55,56]. Both studies reported lower ethanol concentrations and productivities than the present work.…”

Section: Bioreactor Assaysmentioning

confidence: 57%

Ethanol Production from Hydrolyzed Kraft Pulp by Mono- and Co-Cultures of Yeasts: The Challenge of C6 and C5 Sugars Consumption

et al. 2020

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Second-generation bioethanol production's main bottleneck is the need for a costly and technically difficult pretreatment due to the recalcitrance of lignocellulosic biomass (LCB). Chemical pulping can be considered as a LCB pretreatment since it removes lignin and targets hemicelluloses to some extent. Chemical pulps could be used to produce ethanol. The present study aimed to investigate the batch ethanol production from unbleached Kraft pulp of Eucalyptus globulus by separate hydrolysis and fermentation (SHF). Enzymatic hydrolysis of the pulp resulted in a glucose yield of 96.1 ± 3.6% and a xylose yield of 94.0 ± 7.1%. In an Erlenmeyer flask, fermentation of the hydrolysate using Saccharomyces cerevisiae showed better results than Scheffersomyces stipitis. At both the Erlenmeyer flask and bioreactor scale, co-cultures of S. cerevisiae and S. stipitis did not show significant improvements in the fermentation performance. The best result was provided by S. cerevisiae alone in a bioreactor, which fermented the Kraft pulp hydrolysate with an ethanol yield of 0.433 g·g −1 and a volumetric ethanol productivity of 0.733 g·L −1 ·h −1 , and a maximum ethanol concentration of 19.24 g·L −1 was attained. Bioethanol production using the SHF of unbleached Kraft pulp of E. globulus provides a high yield and productivity.Energies 2020, 13, 744 2 of 15 sustainability, has a low and stable price, and practically does not demand extra land [6,7]. There are some facilities producing 2G bioethanol on a commercial scale. However, large-scale production still faces some technological barriers that must be overcome in order to achieve a cost-competitive production [8]. Due to the recalcitrance of LCB, a costly pretreatment step is required, which is the main technological bottleneck of 2G bioethanol production. The release of enzymatic and fermentation inhibitors during pretreatment is another limitation [9].Pulp and paper mills have the infrastructures and logistics to handle LCB, and chemical mills employ technology required for LCB fractionation and conversion [10]. Bioethanol has been produced from different feedstocks such as Kraft pulp, spent sulfite liquor, and pulp and paper sludge [11]. Chemical pulping processes can be considered as a LCB pretreatment since they promote delignification and target hemicelluloses to some degree [12]. Chemical pulping represents about 77% of the virgin pulps produced globally, and more than 95% of these chemical pulps are Kraft pulps [13]. These pulps are produced by Kraft pulping involving the reaction of white liquor, i.e., an alkaline aqueous solution of sodium hydroxide and sodium sulfide with a pH of 14, with lignin at high temperature (150-170 • C). This reaction promotes lignin breakdown and degradation with the release of phenolic fragments, removing almost 90% of the lignin from the wood. Kraft pulping also leads to hemicelluloses and some cellulose loss and decreases the degree of polymerization of cellulose [14]. The utilization of Kraft pulping as a pretreatment method for LCB has ...

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Section: Bioreactor Assaysmentioning

confidence: 57%

Ethanol Production from Hydrolyzed Kraft Pulp by Mono- and Co-Cultures of Yeasts: The Challenge of C6 and C5 Sugars Consumption

et al. 2020

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“…Corn stover, including the leaves, husk, and stalks, comprises up to half of the crop's yield and is one of the most abundant agriculture residues in United States . Raw corn stover consists of about 49.6% glucan, 25.1% xylan, and 23.7% lignin, and has been studied for its potential contribution to the production of biofuels, and biobased lactic acid . Sorghum has been recommended as a feedstock for biofuel production, and of potential crops, has the highest water use efficiency and a high tolerance to low soil fertility .…”

Section: Introductionmentioning

confidence: 99%

d‐lactic acid production from renewable lignocellulosic biomass via genetically modified Lactobacillus plantarum

Zhang

Kumar

Hardwidge

et al. 2016

Biotechnology Progress

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d-lactic acid is of great interest because of increasing demand for biobased poly-lactic acid (PLA). Blending poly-l-lactic acid with poly-d-lactic acid greatly improves PLA's mechanical and physical properties. Corn stover and sorghum stalks treated with 1% sodium hydroxide were investigated as possible substrates for d-lactic acid production by both sequential saccharification and fermentation and simultaneous saccharification and cofermentation (SSCF). A commercial cellulase (Cellic CTec2) was used for hydrolysis of lignocellulosic biomass and an l-lactate-deficient mutant strain Lactobacillus plantarum NCIMB 8826 ldhL1 and its derivative harboring a xylose assimilation plasmid (ΔldhL1-pCU-PxylAB) were used for fermentation. The SSCF process demonstrated the advantage of avoiding feedback inhibition of released sugars from lignocellulosic biomass, thus significantly improving d-lactic acid yield and productivity. d-lactic acid (27.3 g L(-1) ) and productivity (0.75 g L(-1) h(-1) ) was obtained from corn stover and d-lactic acid (22.0 g L(-1) ) and productivity (0.65 g L(-1) h(-1) ) was obtained from sorghum stalks using ΔldhL1-pCU-PxylAB via the SSCF process. The recombinant strain produced a higher concentration of d-lactic acid than the mutant strain by using the xylose present in lignocellulosic biomass. Our findings demonstrate the potential of using renewable lignocellulosic biomass as an alternative to conventional feedstocks with metabolically engineered lactic acid bacteria to produce d-lactic acid. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:271-278, 2016.

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“…Various hydrolytic enzymes are required to achieve efficient biodegradation of lignocellulosic biomass because of its inherent complexity and heterogeneity ( Zambare and Christopher, 2012 ). T. reesei was developed to enhance cellulase production by overexpressing CBHII.…”

Section: Resultsmentioning

confidence: 99%

Thermophilic Geobacillus WSUCF1 Secretome for Saccharification of Ammonia Fiber Expansion and Extractive Ammonia Pretreated Corn Stover

et al. 2022

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A thermophilic Geobacillus bacterial strain, WSUCF1 contains different carbohydrate-active enzymes (CAZymes) capable of hydrolyzing hemicellulose in lignocellulosic biomass. We used proteomic, genomic, and bioinformatic tools, and genomic data to analyze the relative abundance of cellulolytic, hemicellulolytic, and lignin modifying enzymes present in the secretomes. Results showed that CAZyme profiles of secretomes varied based on the substrate type and complexity, composition, and pretreatment conditions. The enzyme activity of secretomes also changed depending on the substrate used. The secretomes were used in combination with commercial and purified enzymes to carry out saccharification of ammonia fiber expansion (AFEX)-pretreated corn stover and extractive ammonia (EA)-pretreated corn stover. When WSUCF1 bacterial secretome produced at different conditions was combined with a small percentage of commercial enzymes, we observed efficient saccharification of EA-CS, and the results were comparable to using a commercial enzyme cocktail (87% glucan and 70% xylan conversion). It also opens the possibility of producing CAZymes in a biorefinery using inexpensive substrates, such as AFEX-pretreated corn stover and Avicel, and eliminates expensive enzyme processing steps that are used in enzyme manufacturing. Implementing in-house enzyme production is expected to significantly reduce the cost of enzymes and biofuel processing cost.

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Optimization of Enzymatic Hydrolysis of Corn Stover for Improved Ethanol Production

Cited by 10 publications

References 37 publications

Ethanol Production from Hydrolyzed Kraft Pulp by Mono- and Co-Cultures of Yeasts: The Challenge of C6 and C5 Sugars Consumption

Ethanol Production from Hydrolyzed Kraft Pulp by Mono- and Co-Cultures of Yeasts: The Challenge of C6 and C5 Sugars Consumption

d‐lactic acid production from renewable lignocellulosic biomass via genetically modified Lactobacillus plantarum

Thermophilic Geobacillus WSUCF1 Secretome for Saccharification of Ammonia Fiber Expansion and Extractive Ammonia Pretreated Corn Stover

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