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Journal ArticleDOI

Consolidated briefing of biochemical ethanol production from lignocellulosic biomass

01 Sep 2016-Electronic Journal of Biotechnology (Pontificia Universidad Católica de Valparaíso)-Vol. 23, Iss: 5, pp 44-53
TL;DR: In this paper, a technological analysis of the biochemical method that can be used to produce bioethanol is carried out and a review of current trends and issues is conducted, which is one pathway for crude oil reduction and environmental compliance.
About: This article is published in Electronic Journal of Biotechnology.The article was published on 2016-09-01 and is currently open access. It has received 140 citations till now. The article focuses on the topics: Energy crop & Biomass.
Citations
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Journal ArticleDOI
TL;DR: In this paper, the authors provide an overview of biogas production from lignocellulosic waste, thus providing information toward crucial issues in the biOGas economy.

380 citations


Cites background from "Consolidated briefing of biochemica..."

  • ...Pretreatment must overcome the structural barriers of lignocellulose and its polymers (cellulose and hemicellulose) by subjecting them to microbial breakdown activities, resulting in enhanced biomass degradation and increased biogas yield [73]....

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Journal ArticleDOI
TL;DR: This review provides an overview of the production of second generation bioethanol, which is distinguished from the first generation and subsequent generations of biofuels by its use of lignocellulosic biomass as raw material.
Abstract: In the context of climate change and the depletion of fossil fuels, there is a great need for alternatives to petroleum in the transport sector. This review provides an overview of the production of second generation bioethanol, which is distinguished from the first generation and subsequent generations of biofuels by its use of lignocellulosic biomass as raw material. The structural components of the lignocellulosic biomass such as cellulose, hemicellulose and lignin, are presented along with technological unit steps including pretreatment, enzymatic hydrolysis, fermentation, distillation and dehydration. The purpose of the pretreatment step is to increase the surface area of carbohydrate available for enzymatic saccharification, while minimizing the content of inhibitors. Performing the enzymatic hydrolysis releases fermentable sugars, which are converted by microbial catalysts into ethanol. The hydrolysates obtained after the pretreatment and enzymatic hydrolysis contain a wide spectrum of sugars, predominantly glucose and xylose. Genetically engineered microorganisms are therefore needed to carry out co-fermentation. The excess of harmful inhibitors in the hydrolysate, such as weak organic acids, furan derivatives and phenol components, can be removed by detoxification before fermentation. Effective saccharification further requires using exogenous hemicellulases and cellulolytic enzymes. Conventional species of distiller's yeast are unable to ferment pentoses into ethanol, and only a very few natural microorganisms, including yeast species like Candida shehatae, Pichia (Scheffersomyces) stipitis, and Pachysolen tannophilus, metabolize xylose to ethanol. Enzymatic hydrolysis and fermentation can be performed in a number of ways: by separate saccharification and fermentation, simultaneous saccharification and fermentation or consolidated bioprocessing. Pentose-fermenting microorganisms can be obtained through genetic engineering, by introducing xylose-encoding genes into metabolism of a selected microorganism to optimize its use of xylose accumulated in the hydrolysate.

359 citations


Cites background or methods from "Consolidated briefing of biochemica..."

  • ...Additionally, biocatalysts such as enzymes are applied for the hydrolysis of polysaccharides, and fermentative microorganisms (yeast or bacteria) for fermentation of mixed sugar streams (15)....

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  • ...Lignocellulosic biomass is a promising substrate for bioethanol production, as it is unlikely to become depleted or suffer permanent damage (15)....

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  • ...Such biomass is usually relatively inexpensive as well as readily and locally available (15)....

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  • ...Biochemical conversion is a common technique for producing bioethanol, because of the high selectivity and efficiency of biomass conversion (7,15)....

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  • ...lignocellulosic feedstock) into valuable products, including ethanol (15,54)....

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Journal ArticleDOI
TL;DR: In this paper, the authors present a review of various approaches made by prominent scientists for efficient utilization of celluloses and hemicelluloses for ethanol production and also describes recent advanced techniques utilized for the same.
Abstract: In response to the scarcity of non-renewable energy sources, sustainable and renewable biofuels from biomass have gained utmost attention. Utilization of lignocellulosic biomass for production of varied energy forms (second generation fuels) like biogas, biodiesel, bioethanol, etc has increased in the past decade. Their properties of being naturally abundant and easily accessible throughout the year, makes them an attractive energy alternative. Efficient pretreatment techniques for effective transformation of lignocelluloses to varied products, by increasing digestibility of celluloses and hemicelluloses can be achieved through acid, alkali treatment, enzymatic hydrolysis, and steam explosion. Idea behind optimizing pretreatment protocol is to maximize release of monosaccharide sugars for conversion to value added products. Tailoring of hydrolytic enzymes through various approaches is well accepted for increasing specific activity of particular enzymatic reaction and can also be clubbed with other pretreatment processes minimizing chemical usage. We at our laboratory are working on optimization of process parameters for enhancing efficiency of saccharification process to obtain maximal monosaccharide sugars that can be converted to bioethanol. Present review compiles various approaches made by prominent scientists for efficient utilization of celluloses and hemicelluloses for ethanol production and also describes recent advanced techniques utilized for the same. Greater emphasis has been led on comparative study on utilization of simple sugars by bacteria and fungi and effect of consolidated bioprocess system on ethanol production from varied agro-industrial wastes.

316 citations

Journal ArticleDOI
TL;DR: A comprehensive and in-depth review on BP for LCB and microalgae biomass by focusing on the relevant overviews and perspectives, technological approaches, mechanisms, influencing factors, and recent research progresses is presented.
Abstract: Biological pretreatment (BP) is a promising approach for treating microalgae and lignocellulosic biomass (LCB) during biofuels production that uses mostly fungal and bacterial strains or their enzymes. Pretreatment with fungi requires long incubation time (weeks to months), whereas, bacterial and enzymatic pretreatments can be completed by only a few hours to days. Nevertheless, fungal pretreatment especially with white-rot fungi (WRF) is predominantly used in BP of biomass for its high efficiency and downstream yields. According to the recent reports, delignification of LCB by WRF may vary between 3% and 72% with a maximum 120% increase in the biofuel yield. Compared to the untreated microalgae biomass, the downstream yields of the respective biofuels were found to be increased by 22–159% after bacterial pretreatment, while enzymatic pretreatment improved as much as 485% of the final yield. Despite the results are promising, exploitation of BP on large scale is still bottlenecked by some technoeconomic hurdles, which need to be overcome through further fundamental and applied researches. This paper presents a comprehensive and in-depth review on BP for LCB and microalgae biomass by focusing on the relevant overviews and perspectives, technological approaches, mechanisms, influencing factors, and recent research progresses. Finally, challenges and future outlooks are discussed in the concluding sections.

278 citations

Journal ArticleDOI
TL;DR: In this article, the role of deep eutectic solvents in biomass processing is discussed, focusing on the impacts of DES on the selectivity of chemical processes and dissolution of biomass.
Abstract: High reliance on crude oil for energy consumption results in the urgent need to explore and develop alternative renewable sources. One of the most promising routes is the transformation of biomass into biofuels and chemicals. The introduction of deep eutectic solvents in 2004 received a considerable amount of attention across different research fields, particularly in biomass processing. The effectiveness of deep eutectic solvents in breaking down the recalcitrant structure in biomass highlights its impact on the transformation of biomass into various value-added products. In addition, deep eutectic solvents are widely regarded as promising “green” solvents due to their low cost, low toxicity, and biodegradable properties. In this paper, some background information on lignocellulosic biomass and deep eutectic solvents is given. Furthermore, the roles of deep eutectic solvents in biomass processing are discussed, focusing on the impacts of deep eutectic solvents on the selectivity of chemical processes and dissolution of biomass. This review also highlights the advantages and limitations of deep eutectic solvents associated with their usage in biomass valorization.

209 citations

References
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Journal ArticleDOI
TL;DR: Simultaneous saccharification and fermentation effectively removes glucose, which is an inhibitor to cellulase activity, thus increasing the yield and rate of cellulose hydrolysis, thereby increasing the cost of ethanol production from lignocellulosic materials.

5,860 citations

Journal ArticleDOI
27 Jan 2006-Science
TL;DR: The integration of agroenergy crops and biorefinery manufacturing technologies offers the potential for the development of sustainable biopower and biomaterials that will lead to a new manufacturing paradigm.
Abstract: Biomass represents an abundant carbon-neutral renewable resource for the production of bioenergy and biomaterials, and its enhanced use would address several societal needs. Advances in genetics, biotechnology, process chemistry, and engineering are leading to a new manufacturing concept for converting renewable biomass to valuable fuels and products, generally referred to as the biorefinery. The integration of agroenergy crops and biorefinery manufacturing technologies offers the potential for the development of sustainable biopower and biomaterials that will lead to a new manufacturing paradigm.

5,344 citations


"Consolidated briefing of biochemica..." refers background in this paper

  • ...Nowadays, the depletion of fossil fuels and the environmental compliance regarding the greenhouse gases has attracted the interest in non-conventional fuel from bioresources [1,2,3,4,5]....

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Journal ArticleDOI
09 Feb 2007-Science
TL;DR: Here, the natural resistance of plant cell walls to microbial and enzymatic deconstruction is considered, collectively known as “biomass recalcitrance,” which is largely responsible for the high cost of lignocellulose conversion.
Abstract: Lignocellulosic biomass has long been recognized as a potential sustainable source of mixed sugars for fermentation to biofuels and other biomaterials. Several technologies have been developed during the past 80 years that allow this conversion process to occur, and the clear objective now is to make this process cost-competitive in today's markets. Here, we consider the natural resistance of plant cell walls to microbial and enzymatic deconstruction, collectively known as "biomass recalcitrance." It is this property of plants that is largely responsible for the high cost of lignocellulose conversion. To achieve sustainable energy production, it will be necessary to overcome the chemical and structural properties that have evolved in biomass to prevent its disassembly.

4,035 citations


"Consolidated briefing of biochemica..." refers background in this paper

  • ...Therefore, these technologies are not economically achievable [32,33]....

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Journal ArticleDOI
TL;DR: Steam pretreatment, lime pret treatment, liquid hot water pretreatments and ammonia based Pretreatments are concluded to be pretreatment with high potentials, providing an improved accessibility of the cellulose for hydrolytic enzymes.

3,618 citations


"Consolidated briefing of biochemica..." refers background in this paper

  • ...Compelling pretreatment is fundamental to an efficient enzymatic hydrolysis [111]....

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Journal ArticleDOI
TL;DR: Transportation biofuels such as synfuel hydrocarbons or cellulosic ethanol, if produced from low-input biomass grown on agriculturally marginal land or from waste biomass, could provide much greater supplies and environmental benefits than food-basedBiofuels.
Abstract: Negative environmental consequences of fossil fuels and concerns about petroleum supplies have spurred the search for renewable transportation biofuels. To be a viable alternative, a biofuel should provide a net energy gain, have environmental benefits, be economically competitive, and be producible in large quantities without reducing food supplies. We use these criteria to evaluate, through life-cycle accounting, ethanol from corn grain and biodiesel from soybeans. Ethanol yields 25% more energy than the energy invested in its production, whereas biodiesel yields 93% more. Compared with ethanol, biodiesel releases just 1.0%, 8.3%, and 13% of the agricultural nitrogen, phosphorus, and pesticide pollutants, respectively, per net energy gain. Relative to the fossil fuels they displace, greenhouse gas emissions are reduced 12% by the production and combustion of ethanol and 41% by biodiesel. Biodiesel also releases less air pollutants per net energy gain than ethanol. These advantages of biodiesel over ethanol come from lower agricultural inputs and more efficient conversion of feedstocks to fuel. Neither biofuel can replace much petroleum without impacting food supplies. Even dedicating all U.S. corn and soybean production to biofuels would meet only 12% of gasoline demand and 6% of diesel demand. Until recent increases in petroleum prices, high production costs made biofuels unprofitable without subsidies. Biodiesel provides sufficient environmental advantages to merit subsidy. Transportation biofuels such as synfuel hydrocarbons or cellulosic ethanol, if produced from low-input biomass grown on agriculturally marginal land or from waste biomass, could provide much greater supplies and environmental benefits than food-based biofuels.

2,841 citations


"Consolidated briefing of biochemica..." refers background in this paper

  • ...Nowadays, the depletion of fossil fuels and the environmental compliance regarding the greenhouse gases has attracted the interest in non-conventional fuel from bioresources [1,2,3,4,5]....

    [...]