scholarly journals Recent advances in bioethanol production from lignocelluloses: a comprehensive review with a focus on enzyme engineering and designer biocatalysts

2020 ◽  
Vol 7 (4) ◽  
pp. 1267-1295
Author(s):  
Yogita Lugani ◽  
Rohit Rai ◽  
Ashish A. Prabhu ◽  
Poonam Maan ◽  
Meenu Hans ◽  
...  
Keyword(s):  
Enzymatic Saccharification ◽  
Strain Improvement ◽  
Deep Eutectic Solvents ◽  
Enzyme Engineering ◽  
Bioethanol Production ◽  
Green Solvents ◽  
Promising Alternative ◽  
Biofuel Policy ◽  
Recent Advances ◽  
Ethanol Yields

Many countries have their biofuel policy programs in place as part of their overall strategy to achieve sustainable development. Among biofuels, bioethanol as a promising alternative to gasoline is of substantial interest. However, there is limited availability of a sufficient quantity of bioethanol to meet demands due to bottlenecks in the present technologies to convert non-edible feedstocks, including lignocelluloses. This review article presents and critically discusses the recent advances in the pretreatment of lignocellulosic biomass, with a focus on the use of green solvents, including ionic liquids and deep eutectic solvents, followed by enzymatic saccharification using auxiliary proteins for the efficient saccharification of pretreated biomass. Different techniques used in strain improvement strategies to develop hyper-producing deregulated lignocellulolytic strains are also compared and discussed. The advanced techniques employed for fermentation of mixed sugars contained in lignocellulosic hydrolysates for maximizing bioethanol production are summarized with an emphasis on pathway and transporters engineering for xylose assimilation. Further, the integration of different steps is suggested and discussed for efficient biomass utilization and improved ethanol yields and productivity.

scholarly journals Aqueous Ammonia With Sodium Sulfite Pretreatment For Enhancing Enzymatic Saccharification and Bioethanol Production of Sugarcane Bagasse

2021 ◽  
Author(s):  
Minxia Zeng ◽  
Baoying Tang ◽  
Peijin Li ◽  
Zhiquan Liang ◽  
Xiaozhen Li ◽  
...  
Keyword(s):  
Sugarcane Bagasse ◽  
Aqueous Ammonia ◽  
Sodium Sulfite ◽  
Enzymatic Saccharification ◽  
Total Sugar ◽  
Bioethanol Production ◽  
Promising Alternative ◽  
Separate Hydrolysis And Fermentation ◽  
Ethanol Yields ◽  
Total Sugar Concentration

Abstract Background: Bioethanol is considered as a promising alternative fuel. Lignocellulosic biomass can be used for the production of bioethanol, but its recalcitrant structure makes it difficult to be utilized. Thus, proper pretreatment is a crucial step to break this structure and enhance enzymatic saccharification. Aqueous ammonia with sodium sulfite pretreatment (AAWSSP) was first applied to enhance the enzymatic saccharification and bioethanol production of sugarcane bagasse (SCB) in this research.Results: Response surface methodology was applied to optimize the conditions of pretreatment. Under optimal parameters, 16.92 g/L of total sugar concentration (P1 SCB: 202.08℃, 11.06% aqueous ammonia, 13.37% sodium sulfite, 1.22 h) and 0.51 g/g of total sugar yield (P2 SCB: 199.47℃, 10.17% aqueous ammonia, 13.11% sodium sulfite, 1.17 h) were achieved, respectively. The results of ethanol fermentation showed that separate hydrolysis and fermentation performed better than that of simultaneous saccharification and fermentation, and the maximum ethanol yields of 143.30 g/kg for P1 SCB and 145.33 g/kg for P2 SCB, were obtained, respectively. Conclusions: This research indicated that aqueous ammonia and sodium sulfite in pretreatment solution might have a synergistic effect on delignification and enzymatic saccharification. AAWSSP might be a prospective method for enhancing enzymatic saccharification and bioethanol production of SCB, which provided new guidance for the bio-refinery of lignocellulose.

scholarly journals Valorisation of bambara and cowpea haulms for bioethanol production

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.

scholarly journals Diverse Banana Pseudostems and Rachis Are Distinctive for Edible Carbohydrates and Lignocellulose Saccharification towards High Bioethanol Production under Chemical and Liquid Hot Water Pretreatments

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3870
Author(s):  
Jingyang Li ◽  
Fei Liu ◽  
Hua Yu ◽  
Yuqi Li ◽  
Shiguang Zhou ◽  
...  
Keyword(s):  
Soluble Sugars ◽  
Enzymatic Saccharification ◽  
Hot Water ◽  
Biofuel Production ◽  
Bioenergy Crops ◽  
Bioethanol Production ◽  
Factors Affecting ◽  
Liquid Hot Water ◽  
Biomass Processing ◽  
Banana Crops

Banana is a major fruit crop throughout the world with abundant lignocellulose in the pseudostem and rachis residues for biofuel production. In this study, we collected a total of 11 pseudostems and rachis samples that were originally derived from different genetic types and ecological locations of banana crops and then examined largely varied edible carbohydrates (soluble sugars, starch) and lignocellulose compositions. By performing chemical (H2SO4, NaOH) and liquid hot water (LHW) pretreatments, we also found a remarkable variation in biomass enzymatic saccharification and bioethanol production among all banana samples examined. Consequently, this study identified a desirable banana (Refen1, subgroup Pisang Awak) crop containing large amounts of edible carbohydrates and completely digestible lignocellulose, which could be combined to achieve the highest bioethanol yields of 31–38% (% dry matter), compared with previously reported ones in other bioenergy crops. Chemical analysis further indicated that the cellulose CrI and lignin G-monomer should be two major recalcitrant factors affecting biomass enzymatic saccharification in banana pseudostems and rachis. Therefore, this study not only examined rich edible carbohydrates for food in the banana pseudostems but also detected digestible lignocellulose for bioethanol production in rachis tissue, providing a strategy applicable for genetic breeding and biomass processing in banana crops.

Strategies for metal colloidal nancrystal synthesis in sustainable media

2019 ◽  
Author(s):  
◽  
Nakara Bhawawet
Keyword(s):  
Deep Eutectic Solvents ◽  
Chemical Processes ◽  
Green Solvents ◽  
University Of Missouri ◽  
Synthetic Strategy ◽  
Metal Colloid ◽  
Gold Precursor ◽  
Nanocrystal Synthesis ◽  
Sustainable Media ◽  
Colloid Synthesis

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Over the past decades, the Green Chemistry and Sustainability concept has aroused researchers to denounce their traditional ways of thinking regarding chemical processes to address the challenges relevant to global environmental concerns. The concept has demonstrated how fundamental scientific methodologies can protect human health and the environment in an economically beneficial manner. In academia and industry, the use of green solvents, such as water, supercritical fluids, ionic liquids (ILs) and deep eutectic solvents (DESs), has then become desirable in chemical processes. In the field of green nanochemistry, ILs and DESs have acquired courtesy as sustainable media for nanomaterials synthesis. There have been attempts to employ such eco-friendly fluids to synthesize, and additionally, control size and shapes of nanomaterials, where the field has been gaining intense interests as the morphology dictates the properties and functionalities of such nanomaterials. This dissertation reports strategies for metal colloidal nanocrystal synthesis in sustainable media and aims to build a foundation for understanding how to tailor eco-friendly IL and DES fluids to control the growth of metal nanocrystals. Chapter 1 explores research reporting strategies used for metal colloid synthesis in ILs and DESs. In Chapter 2, we have developed a strategy to replace a common organic solvent with an IL to prepare monodisperse gold nanoparticles (AuNPs) by a very fast microwave method. The pyrrolidinium IL used in the work demonstrates its capability to be efficiently recovered and reused for carrying out nanoscale synthesis iteratively. The work highlights the incompatibility of imidazolium ILs for the select nanoscale synthetic strategy. For Chapter 3, we have demonstrated a control over nanoparticle size and shape generated at an aqueous-organic interface. We have shown that an interfacial photoreduction leads to the production of spherical and wire-like nanostructures, respectively, when the IL employed involves a coordinated and non-coordinated IL anion, respectively. Next, Chapter 4 has focused on exploitation of a purposefully designed IL-inspired surfactant, acting dually as a reducing and stabilizing agent, for facile and controllable AuNP formation. The reported synthetic method is simple and rapid, using only a gold precursor and the surfactant. Coinage AuNPs can be obtained very fast, while predominantly triangular-shaped AuNPs can also be achieved by tuning parameters, such as the ratio of surfactant to the gold precursor, temperature, implementing a time delay before heating, and an addition of a directing agent. Finally, Chapter 5 outlines zwitterionic deep eutectic solvents (ZDESs) as novel media for metal nanocrystal synthesis, to expand portfolio of available DESs as the field is relatively new compared to that of IL.

scholarly journals Green aqueous biphasic systems containing deep eutectic solvents and sodium salts for the extraction of protein

RSC Advances ◽  
2017 ◽  
Vol 7 (78) ◽  
pp. 49361-49367 ◽  
Author(s):  
Jingyu Pang ◽  
Xiaofang Sha ◽  
Yanhong Chao ◽  
Guangying Chen ◽  
Changri Han ◽  
...  
Keyword(s):  
Deep Eutectic Solvents ◽  
Green Solvents ◽  
Sodium Salts ◽  
Aqueous Biphasic Systems ◽  
New Type ◽  
Aqueous Biphasic ◽  
Biphasic Systems

Deep eutectic solvents (DESs), a new type of green solvents, were applied for the extraction of proteins with aqueous biphasic systems (ABSs) in this study.

Enzymatic saccharification of agar waste from Gracilaria verrucosa and Gelidium latifolium for bioethanol production

2017 ◽  
Vol 29 (6) ◽  
pp. 3201-3209 ◽  
Author(s):  
Maria Dyah Nur Meinita ◽  
Bintang Marhaeni ◽  
Yong-Ki Hong ◽  
Gwi-Taek Jeong
Keyword(s):  
Enzymatic Saccharification ◽  
Gracilaria Verrucosa ◽  
Bioethanol Production ◽  
Gelidium Latifolium

scholarly journals Investigation of Base-free Copper-Catalysed Azide–Alkyne Click Cycloadditions (CuAAc) in Natural Deep Eutectic Solvents as Green and Catalytic Reaction Media

2021 ◽  
Author(s):  
Salvatore V. Giofrè ◽  
Matteo Tiecco ◽  
Angelo Ferlazzo ◽  
Roberto Romeo ◽  
Gianluca Ciancaleoni ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Materials Science ◽  
Cycloaddition Reaction ◽  
Deep Eutectic Solvents ◽  
Green Solvents ◽  
Experimental Conditions ◽  
Active Reaction ◽  
Natural Deep Eutectic Solvents ◽  
Catalytic Intermediates ◽  
Reaction Media

<p>The click cycloaddition reaction of azides and alkynes affording 1,2,3-triazoles is a widely used and effective chemical transformation, applied to obtain relevant products in medicine, biology and materials science. In this work, a set of Natural Deep Eutectic Solvents (NADESs) as green and “active” reaction media, has been investigated in the copper-catalysed azide–alkyne cycloaddition reactions (CuAAc). The use of these innovative solvents has shown to improve the reaction effectiveness, giving excellent yields. NADESs proved to be “active” in these transformations for the absence of added bases in all the performed reactions and in several cases, for their reducing capabilities. The reactions outcomes were rationalized by DFT calculations which demonstrated the involvement of H-bonds between DESs and alkynes as well as a stabilization of copper catalytic intermediates. The green experimental conditions, namely the absence of a base, the low temperatures, the lowering of reagents and the possibility of recycling of the green solvents, outline the great potential of NADESs for CuAAc and in general, for green organic synthesis. </p>

Bioethanol production by enzymatic saccharification ofSalix viminalisvar.giganteabiomass

2014 ◽  
Vol 10 (2) ◽  
pp. 67-72
Author(s):  
Hak-Gon Kim ◽  
Hyun-Jin Song ◽  
Mi-Jin Jeong ◽  
Young-Long Seo ◽  
Jae-Kyung Yang ◽  
...  
Keyword(s):  
Enzymatic Saccharification ◽  
Bioethanol Production
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