Potential of Ceiba pentandra (L.) Gaertn. (kapok) fiber as a resource for second generation bioethanol: Parametric optimization and comparative study of various pretreatments prior enzymatic saccharification for sugar production

This study aims to establish a natural cellulosic biomass pretreatment process using ionic liquid (IL) for efficient enzymatic hydrolysis and second generation bioethanol. The IL 1-Butyl-3-methylimidazolium Chloride/FeCl3 ([Bmim]Cl/FeCl3) was selected in view of its low temperature pretreatment ability and the potential of accelerating enzymatic hydrolysis, and it could be recyclable. The yield of reducing sugars from sugarcane residue pretreated with this IL at 80 oC for 1 h reached 46.8% after being enzymatically hydrolyzed for 24 h. Sugarcane residue regenerated were hydrolyzed more easily than that treated with water. The fermentability of the hydrolyzates, obtained after enzymatic saccharification of the regenerated sugarcane residue, was transformed into bioethanol using Candida shehatae. This microbe could absorb glucose and xylose efficiently, and the ethanol production was 0.38 g/g glucose within 30 h fermentation. In conclusion, the metal ionic liquid pretreatment in low temperature shows promise as pretreatment solvent for natural biomass.

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Plant cell walls to ethanol

Biochemical Journal ◽

10.1042/bj20111922 ◽

2012 ◽

Vol 442 (2) ◽

pp. 241-252 ◽

Cited By ~ 133

Author(s):

Douglas B. Jordan ◽

Michael J. Bowman ◽

Jay D. Braker ◽

Bruce S. Dien ◽

Ronald E. Hector ◽

...

Keyword(s):

Plant Cell ◽

Cell Walls ◽

Second Generation ◽

Consolidated Bioprocessing ◽

Enzymatic Saccharification ◽

Crystalline Cellulose ◽

Plant Cell Walls ◽

Second Generation Bioethanol ◽

Single Organism ◽

The Cost

Conversion of plant cell walls to ethanol constitutes second generation bioethanol production. The process consists of several steps: biomass selection/genetic modification, physiochemical pretreatment, enzymatic saccharification, fermentation and separation. Ultimately, it is desirable to combine as many of the biochemical steps as possible in a single organism to achieve CBP (consolidated bioprocessing). A commercially ready CBP organism is currently unreported. Production of second generation bioethanol is hindered by economics, particularly in the cost of pretreatment (including waste management and solvent recovery), the cost of saccharification enzymes (particularly exocellulases and endocellulases displaying kcat ~1 s−1 on crystalline cellulose), and the inefficiency of co-fermentation of 5- and 6-carbon monosaccharides (owing in part to redox cofactor imbalances in Saccharomyces cerevisiae).

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Alternative Lime Pretreatment of Corn Stover for Second-Generation Bioethanol Production

Agronomy ◽

10.3390/agronomy11010155 ◽

2021 ◽

Vol 11 (1) ◽

pp. 155

Author(s):

Iria Fírvida ◽

Pablo G. del Río ◽

Patricia Gullón ◽

Beatriz Gullón ◽

Gil Garrote ◽

...

Keyword(s):

Corn Stover ◽

Second Generation ◽

Solid Phase ◽

Enzymatic Saccharification ◽

Effect Of Temperature ◽

Ethanol Conversion ◽

Second Generation Bioethanol ◽

Lime Pretreatment ◽

Simultaneous Saccharification ◽

Successful Production

In this work, a delignification process, using lime (Ca(OH)2) as an alternative alkali, was evaluated to improve enzymatic saccharification of corn stover cellulose, with the final goal of obtaining second-generation bioethanol. For that, an experimental design was conducted in order to assay the effect of temperature, lime loading, and time on the corn stover fractionation and enzymatic susceptibility of cellulose. Under conditions evaluated, lime pretreatment was selective for the recovery of cellulose (average of 91%) and xylan (average of 75.3%) in the solid phase. In addition, operating in mild conditions, a delignification up to 40% was also attained. On the other hand, a maximal cellulose-to-glucose conversion (CGCMAX) of 89.5% was achieved using the solid, resulting from the treatment carried out at 90 °C for 5 h and lime loading of 0.4 g of Ca(OH)2/g of corn stover. Finally, under selected conditions of pretreatment, 28.7 g/L (or 3.6% v/v) of bioethanol was produced (corresponding to 72.4% of ethanol conversion) by simultaneous saccharification and fermentation. Hence, the process, based on an alternative alkali proposed in this work, allowed the successful production of biofuel from the important and abundant agro-industrial residue of corn stover.

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Optimization of sugar production from Durian seeds via alkaline hydrolysis for second-generation bioethanol production

Clean Energy ◽

10.1093/ce/zkab020 ◽

2021 ◽

Vol 5 (2) ◽

pp. 375-386

Author(s):

Theofany Harley Chriswardana ◽

Yheni Mulyaningsih ◽

Yhana Mulyaningsih ◽

Aditiya Harjon Bahar ◽

Teuku Meurah Indra Riayatsyah

Keyword(s):

Alkaline Hydrolysis ◽

Second Generation ◽

Quadratic Model ◽

Sugar Production ◽

Bioethanol Production ◽

Hydrolysis Time ◽

Tropical Country ◽

Second Generation Bioethanol ◽

Hydrolysis Temperature ◽

Optimized Conditions

Abstract As one way to eliminate the issues found in the preceding generation, feedstock exploration in second-generation bioethanol production remains an issue, especially for a tropical country such as Indonesia. From exotic fruit by-products, durian holds a promising perspective that rests on its abundance, superb carbohydrate content and limited usage until now. This work presents the first-ever utilization of durian seeds for sugar production under optimized conditions through alkaline hydrolysis. A simple form of sugar was extracted by varying four parameters, namely substrate loading, NaOH concentration, hydrolysis time and hydrolysis temperature. Response surface methodology based on the Box-Behnken design was employed to outline the most optimum parameter values. Analysis of variance revealed that the quadratic model fit the data appropriately with the order of significance as substrate loading > hydrolysis time > NaOH concentration > hydrolysis temperature. The optimized conditions for reducing sugar yield, as high as 2.140 g/L, corresponded to <50 g/L substrate loading, 0.522 M NaOH, 60 minutes of hydrolysis time and 80oC hydrolysis temperature. The possible ethanol content of 1.094 g/L was also expected under optimized conditions, demonstrating great potential in second-generation bioethanol production. Second-generation bioethanol production from a non-edible feedstock (durian seeds) is optimized by varying key parameters in the alkaline hydrolysis process, showing high yields of fermentable sugars.

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Second Generation Bioethanol: Challenges and Perspectives

Journal of Biotechnology ◽

10.1016/j.jbiotec.2010.10.006 ◽

2010 ◽

Vol 150 ◽

pp. 553-553

Author(s):

Andre Koltermann

Keyword(s):

Second Generation ◽

Second Generation Bioethanol

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Identification of the major fermentation inhibitors of recombinant 2G yeasts in diverse lignocellulose hydrolysates

Biotechnology for Biofuels ◽

10.1186/s13068-021-01935-9 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Gert Vanmarcke ◽

Mekonnen M. Demeke ◽

Maria R. Foulquié-Moreno ◽

Johan M. Thevelein

Keyword(s):

Second Generation ◽

Industrial Process ◽

Superior Performance ◽

Fermentation Inhibitors ◽

Inhibitor Tolerance ◽

Xylose Consumption ◽

Process Economics ◽

Partial Inhibition ◽

Second Generation Bioethanol ◽

Lignocellulose Hydrolysates

Abstract Background Presence of inhibitory chemicals in lignocellulose hydrolysates is a major hurdle for production of second-generation bioethanol. Especially cheaper pre-treatment methods that ensure an economical viable production process generate high levels of these inhibitory chemicals. The effect of several of these inhibitors has been extensively studied with non-xylose-fermenting laboratory strains, in synthetic media, and usually as single inhibitors, or with inhibitor concentrations much higher than those found in lignocellulose hydrolysates. However, the relevance of individual inhibitors in inhibitor-rich lignocellulose hydrolysates has remained unclear. Results The relative importance for inhibition of ethanol fermentation by two industrial second-generation yeast strains in five lignocellulose hydrolysates, from bagasse, corn cobs and spruce, has now been investigated by spiking higher concentrations of each compound in a concentration range relevant for industrial hydrolysates. The strongest inhibition was observed with industrially relevant concentrations of furfural causing partial inhibition of both D-glucose and D-xylose consumption. Addition of 3 or 6 g/L furfural strongly reduced the ethanol titer obtained with strain MD4 in all hydrolysates evaluated, in a range of 34 to 51% and of 77 to 86%, respectively. This was followed by 5-hydroxymethylfurfural, acetic acid and formic acid, for which in general, industrially relevant concentrations caused partial inhibition of D-xylose fermentation. On the other hand, spiking with levulinic acid, 4-hydroxybenzaldehyde, 4-hydroxybenzoic acid or vanillin caused little inhibition compared to unspiked hydrolysate. The further evolved MD4 strain generally showed superior performance compared to the previously developed strain GSE16-T18. Conclusion The results highlight the importance of individual inhibitor evaluation in a medium containing a genuine mix of inhibitors as well as the ethanol that is produced by the fermentation. They also highlight the potential of increasing yeast inhibitor tolerance for improving industrial process economics.

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