Evaluation of Copper-Contaminated Marginal Land for the Cultivation of Vetiver Grass (Chrysopogon zizanioides) as a Lignocellulosic Feedstock and its Impact on Downstream Bioethanol Production

Metal-contaminated soil could be sustainably used for biofuel feedstock production if the harvested biomass is amenable to bioethanol production. A 60-day greenhouse experiment was performed to evaluate (1) the potential of vetiver grass to phytostabilize soil contaminated with copper (Cu), and (2) the impact of Cu exposure on its lignocellulosic composition and downstream bioethanol production. Dilute acid pretreatment, enzymatic hydrolysis, and fermentation parameters were optimized sequentially for vetiver grass using response surface methodology (RSM). Results indicate that the lignocellulosic composition of vetiver grown on Cu-rich soil was favorably altered with a significant decrease in lignin and increase in hemicellulose and cellulose content. Hydrolysates produced from Cu exposed biomass achieved a significantly greater ethanol yield and volumetric productivity compared to those of the control biomass. Upon pretreatment, the hemicellulosic hydrolysate showed an increase in total sugars per liter by 204.7% of the predicted yield. After fermentation, 110% of the predicted ethanol yield was obtained for the vetiver grown on Cu-contaminated soil. By contrast, for vetiver grown on uncontaminated soil a 62.3% of theoretical ethanol yield was achieved, indicating that vetiver has the potential to serve the dual purpose of phytoremediation and biofuel feedstock generation on contaminated sites.

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Sustainable 2G Ethanol Production From Switchgrass Biomass via Co-Fermentation of Pentoses and Hexoses Using Novel Wild Yeasts

10.21203/rs.3.rs-259640/v1 ◽

2021 ◽

Author(s):

Felipe A. F. Antunes ◽

Kalavathy Rajan ◽

Angele Djioleu ◽

Thiago M. Rocha ◽

Larissa P. Brumano ◽

...

Keyword(s):

Ethanol Production ◽

Ethanol Yield ◽

Enzymatic Saccharification ◽

Dilute Acid Pretreatment ◽

Acid Pretreatment ◽

Lignocellulosic Feedstock ◽

Lignocellulosic Feedstocks ◽

Wild Yeasts ◽

Alkaline Delignification ◽

Maximum Utilization

Abstract The production of second generation (2G) ethanol remains an interesting proposition for the implementation of sustainable and net carbon-neutral energy systems. 2G makes use of renewable lignocellulosic feedstocks, generating fermentable sugars that are converted to ethanol or other bio-based products. To be economically viable, 2G biorefineries must make use of all processing streams, including the less desirable C5 sugar stream. In this work, a strategy of sequential acid and alkaline pretreatment of the lignocellulosic feedstock switchgrass for improvement of fermentable sugar yield, and the subsequent utilization of wild yeasts for co-fermentation of its C5-C6 sugar streams are presented. Hemicellulose-enriched hydrolysates, obtained by dilute acid pretreatment of switchgrass, were fermented by a newly-isolated wild Scheffersomyces parashehatae strain–UFMG-HM-60.1b; corresponding ethanol yield (YPS) and volumetric productivity (QP) were 0.19 g/g and 0.16 g/L h, respectively. Afterwards, the remaining switchgrass cellulignin fraction was subjected to optimized alkaline delignification at 152 ºC for 30 min. The delignified solid fraction was subjected to contiguous enzymatic saccharification and fermentation, releasing a C6 sugar stream in which Saccharomyces cerevisiae 174 strain displayed a productivity of 0.46 g/g (YPS) and 0.70 g/L h (QP), whereas the S. parashehatae UFMG-HM-60.1b presented YPS and QP of 0.29 g/g and 0.38 g/L h, respectively. Upon combining the conversion of hemicellulose (37%) and cellulose-derived sugars (57%), the S. parashehatae strain provided higher yield (94%) than the generic S. cerevisiae (90%). Henceforth, our integrated pretreatment and co-fermentation process provides a pathway for maximum utilization of the switchgrass carbohydrates for 2G ethanol production.

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Dilute acid pretreatment of pine needles of Pinus roxburghii by response surface methodology for bioethanol production by separate hydrolysis and fermentation

Biomass Conversion and Biorefinery ◽

10.1007/s13399-019-00433-1 ◽

2019 ◽

Vol 10 (1) ◽

pp. 95-106 ◽

Cited By ~ 3

Author(s):

Parvez Singh Slathia ◽

Neelu Raina ◽

Asha Kiran ◽

Rizem Kour ◽

Deepali Bhagat ◽

...

Keyword(s):

Response Surface Methodology ◽

Response Surface ◽

Pine Needles ◽

Dilute Acid Pretreatment ◽

Bioethanol Production ◽

Dilute Acid ◽

Acid Pretreatment ◽

Pinus Roxburghii ◽

Separate Hydrolysis And Fermentation

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Genetic Engineering of Enterobacter asburiae Strain JDR-1 for Efficient Production of Ethanol from Hemicellulose Hydrolysates

Applied and Environmental Microbiology ◽

10.1128/aem.01180-09 ◽

2009 ◽

Vol 75 (18) ◽

pp. 5743-5749 ◽

Cited By ~ 15

Author(s):

Changhao Bi ◽

Xueli Zhang ◽

Lonnie O. Ingram ◽

James F. Preston

Keyword(s):

Ethanol Yield ◽

Maximum Yield ◽

Pyruvate Decarboxylase ◽

Dry Weight ◽

Dilute Acid Pretreatment ◽

Efficient Production ◽

Dilute Acid ◽

Acid Pretreatment ◽

Acid Fermentation ◽

Enterobacter Asburiae

ABSTRACT Dilute acid pretreatment is an established method for hydrolyzing the methylglucuronoxylans of hemicellulose to release fermentable xylose. In addition to xylose, this process releases the aldouronate methylglucuronoxylose, which cannot be metabolized by current ethanologenic biocatalysts. Enterobacter asburiae JDR-1, isolated from colonized wood, was found to efficiently ferment both methylglucuronoxylose and xylose in acid hydrolysates of sweet gum xylan, producing predominantly ethanol and acetate. Transformation of E. asburiae JDR-1 with pLOI555 or pLOI297, each containing the PET operon containing pyruvate decarboxylase (pdc) and alcohol dehydrogenase B (adhB) genes derived from Zymomonas mobilis, replaced mixed-acid fermentation with homoethanol fermentation. Deletion of the pyruvate formate lyase (pflB) gene further increased the ethanol yield, resulting in a stable E. asburiae E1(pLOI555) strain that efficiently utilized both xylose and methylglucuronoxylose in dilute acid hydrolysates of sweet gum xylan. Ethanol was produced from xylan hydrolysate by E. asburiae E1(pLOI555) with a yield that was 99% of the theoretical maximum yield and at a rate of 0.11 g ethanol/g (dry weight) cells/h, which was 1.57 times the yield and 1.48 times the rate obtained with the ethanologenic strain Escherichia coli KO11. This engineered derivative of E. asburiae JDR-1 that is able to ferment the predominant hexoses and pentoses derived from both hemicellulose and cellulose fractions is a promising subject for development as an ethanologenic biocatalyst for production of fuels and chemicals from agricultural residues and energy crops.

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The influence of ferrous sulfate utilization on the sugar yields from dilute-acid pretreatment of softwood for bioethanol production

Bioresource Technology ◽

10.1016/j.biortech.2010.08.077 ◽

2011 ◽

Vol 102 (2) ◽

pp. 1103-1108 ◽

Cited By ~ 27

Author(s):

Sanam Monavari ◽

Mats Galbe ◽

Guido Zacchi

Keyword(s):

Ferrous Sulfate ◽

Dilute Acid Pretreatment ◽

Bioethanol Production ◽

Dilute Acid ◽

Acid Pretreatment

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Valorisation of bambara and cowpea haulms for bioethanol production

10.51415/10321/3607 ◽

2020 ◽

Author(s):

◽

Somiame Itseme Okuofu

Keyword(s):

Ethanol Yield ◽

Promising Result ◽

Choline Chloride ◽

Deep Eutectic Solvent ◽

Enzymatic Saccharification ◽

Deep Eutectic Solvents ◽

Sugar Yield ◽

Dilute Acid Pretreatment ◽

Bioethanol Production ◽

Dilute Acid

Bambara and cowpea are important pulses grown in semi-arid South Africa due to their balanced nutrient profile and drought resilient capacity. The haulm is the lignocellulosic residue obtained after grain harvest and are rich in carbohydrates. However, these haulms are underutilised and under researched. The aim of the study, therefore, was to investigate the potential to valorise bambara haulms (BGH) and cowpea haulms (CH) to bioethanol which is the most promising biofuel with commercial prospects currently. The structural and chemical composition of BGH and CH was elucidated using techniques such as compositional analysis, XRD, FTIR, ICP-AES, and SEM. Results indicated a volatile matter and fixed carbon mass fraction of 77.70% and 13.15% (w/w) in BGH and 76.16% and 16.26% (w/w) in CH respectively. The polysaccharides make up the largest fraction (51%), followed by extractives (> 20%), while the lignin in BGH (12%) and CH (10%) was low. X-ray diffraction pattern showed a higher percentage of amorphous regions in BGH (78%) than CH (56%). CH was then subjected to dilute acid pretreatment (DAP) to enhance biosugar production for bioethanol fermentation. The effects of operational factors for DAP including temperature, time, and acid concentration on sugar yield and inhibitor formation was investigated and optimised using response surface methodology (RSM). The solid recovered after DAP was subjected to prehydrolysis with simultaneous saccharification and fermentation (PSSF). In addition, the pretreatment hydrolysate was detoxified and fermented to ethanol using cocultures of Saccharomyces cerevisiae BY4743 and Scheffersomyces stipitis wild type (PsY633). A total ethanol titre of 15.67 g/L was obtained corresponding to 75% conversion efficiency. On the other hand, BGH was subjected to deep eutectic solvent (DES) pretreatment. Five deep eutectic solvents were prepared and screened for their effectiveness in improving enzymatic sugar yield. This was achieved by pretreating BGH with each DES followed by a 48 h enzymatic saccharification. Choline chloride – lactic acid (ChCl-LA) treatment provided the most promising result and was further optimised by investigating the effect of different temperatures and time on cellulose loss and enzymatic sugar yield. ChCl-LA pretreatment at 100°C for 1 h was observed to be the best condition for maximum sugar recovery. The hydrolysate thus obtained was concentrated and fermented for 72 h with S. cerevisiae BY4743. A maximum ethanol yield of 11.57 g/L was obtained. From the results, it is evident that bambara and cowpea haulm are promising substrates for bioethanol production. Dilute acid hydrolysis was shown to be effective in the pretreatment of CH with over 85% of the theoretical sugar recoverable for conversion to bioethanol. In addition, deep eutectic solvents are effective media for breaking the recalcitrance in BGH to achieve high sugar yield for conversion to bioethanol. However, further studies are required to reduce cellulose loss during pretreatment to improve bioethanol yield.

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CELLULOSIC BIOETHANOL PRODUCTION FROM ULVA LACTUCA MACROALGAE

Cellulose Chemistry and Technology ◽

10.35812/cellulosechemtechnol.2021.55.51 ◽

2021 ◽

Vol 55 (5-6) ◽

pp. 629-635

Author(s):

AMINA ALLOUACHE ◽

AZIZA MAJDA ◽

AHMED ZAID TOUDERT ◽

ABDELTIF AMRANE ◽

MERCEDES BALLESTEROS

Keyword(s):

Enzymatic Hydrolysis ◽

Fossil Fuels ◽

Ethanol Yield ◽

Lignin Content ◽

Arable Land ◽

Ulva Lactuca ◽

Marine Macroalgae ◽

Bioethanol Production ◽

Acid Pretreatment ◽

Total Glucose

Nowadays, the use of biofuels has become an unavoidable solution to the depletion of fossil fuels and global warming. The controversy over the use of food crops for the production of the first-generation biofuels and deforestation caused by the second-generation ones has forced the transition to the third generation of biofuels, which avoids the use of arable land and edible products, and does not threaten biodiversity. This generation is based on the marine and freshwater biomass, which has the advantages of being abundant or even invasive, easy to cultivate and having a good energetic potential. Bioethanol production from Ulva lactuca, a local marine macroalgae collected from the west coast of Algiers, was examined in this study. Ulva lactuca showed a good energetic potential due to its carbohydrate-rich content: 9.57% of cellulose, 6.9% of hemicellulose and low lignin content of 5.11%. Ethanol was produced following the separate hydrolysis and fermentation process (SHF), preceded by a thermal acid pretreatment at 120 °C during 15 min. Enzymatic hydrolysis was performed using a commercial cellulase (Celluclast 1.5 L), which saccharified the cellulose contained in the green seaweed, releasing about 85.01% of the total glucose, corresponding to 7.21 g/L after 96 h of enzymatic hydrolysis at pH 5 and 45 °C. About 3.52 g/L of ethanol was produced after 48 h of fermentation using Saccharomyces cerevisiae at 30 °C and pH 5, leading to a high ethanol yield of 0.41 g of ethanol/g of glucose.

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