Recent advances and future directions in plant and yeast engineering to improve lignocellulosic biofuel production
TL;DR: The objective of this review is to discuss the technological advances in engineering lignocellulosic biomass as an economically attractive feedstock and robust microbial platforms as a powerful biofuel producer.
Abstract: Lignocellulosic biofuel has been globally recognized as a renewable energy source with environmental benefits while minimizing the competition between food and fuel supply. Although lignocellulose is a promising renewable feedstock for the sustainable production of transportation fuels, cost-effective conversion technologies are necessary to overcome its inherent recalcitrance that impedes the widespread utilization of lignocellulosic biofuels. Owing to the limited availability of cost-effective and less recalcitrant biomass, the major challenge toward biofuel commercialization includes the biochemical and genetic modification of lignocellulose in energy crops. The development of robust microbial conversion systems capable of converting a broad spectrum of carbon sources derived from biomass feedstocks into a variety of biofuels such as bioethanol, biodiesel, and advanced drop-in biofuels is also of interest in the field of biorefinery. To date, metabolic engineering and synthetic biology have made significant advances in improving the biofuel yield in feedstocks and microbial engineering. The objective of this review is to discuss the technological advances in engineering lignocellulosic biomass as an economically attractive feedstock and robust microbial platforms as a powerful biofuel producer. Finally, integrating engineering strategies and efforts in plant and microbial engineering provides future directions of an interdisciplinary approach to facilitate the commercialization of economically feasible lignocellulosic biofuels.
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TL;DR: In this paper, the importance of integration of lignocellulosic biorefineries with existing petrochemical refineries, the technical challenges of industrialization, SWOT analysis, and future directions have been reviewed.
57 citations
TL;DR: In this paper , the importance of integration of lignocellulosic biorefineries with existing petrochemical refineries, the technical challenges of industrialization, SWOT analysis, and future directions have been reviewed.
57 citations
07 Jan 2021
TL;DR: In this paper, a review article focuses on the recent trends and researches carried out in liquid biofuel production and economy holding its future demand and utilization world-wide, focusing on the appropriate policies, production costing, yield, purity and efficiency to achieve a sustainable energy in future.
Abstract: Fossil depletion is facing critical crisis due to its depletion reserves and increased environmental problems. The utilization of petroleum products by the dense population, urbanization of various geographical areas and industrialization has extremely affected the global economy. Fuels of biological origin such as ethanol, vegetable oil and various biomasses are gaining attention It is therefore important to develop alternative fuels in order to protect the global environment and also to focus on long-term supplies of conventional fuels. These biofuels have greater opportunity to promote agro-industrial development and productivity in large scale. Thus, it is necessary to improvise technology and develop resource sustainability focussing into the appropriate policies, production costing, yield, purity and efficiency creating health, wealth and benefit sharing to achieve a sustainable energy in future. The present review article focuses on the recent trends and researches carried out in liquid biofuel production and economy holding its future demand and utilization world-wide.
35 citations
TL;DR: In this article , a review of the preprocessing procedures utilized previously to biomass thermal conversion techniques, in order to promote the sustainable production of biofuels and other commodities from biomass, is presented.
17 citations
TL;DR: Looking forward, future advances to achieve economically feasible production of lignocellulosic-based biofuels with special focus on designing more efficient metabolic pathways coupled with screening, and engineering of novel enzymes are expected.
Abstract: ABSTRACT Combating climate change and ensuring energy supply to a rapidly growing global population has highlighted the need to replace petroleum fuels with clean, and sustainable renewable fuels. Biofuels offer a solution to safeguard energy security with reduced ecological footprint and process economics. Over the past years, lignocellulosic biomass has become the most preferred raw material for the production of biofuels, such as fuel, alcohol, biodiesel, and biohydrogen. However, the cost-effective conversion of lignocellulose into biofuels remains an unsolved challenge at the industrial scale. Recently, intensive efforts have been made in lignocellulose feedstock and microbial engineering to address this problem. By improving the biological pathways leading to the polysaccharide, lignin, and lipid biosynthesis, limited success has been achieved, and still needs to improve sustainable biofuel production. Impressive success is being achieved by the retouring metabolic pathways of different microbial hosts. Several robust phenotypes, mostly from bacteria and yeast domains, have been successfully constructed with improved substrate spectrum, product yield and sturdiness against hydrolysate toxins. Cyanobacteria is also being explored for metabolic advancement in recent years, however, it also remained underdeveloped to generate commercialized biofuels. The bacterium Escherichia coli and yeast Saccharomyces cerevisiae strains are also being engineered to have cell surfaces displaying hydrolytic enzymes, which holds much promise for near-term scale-up and biorefinery use. Looking forward, future advances to achieve economically feasible production of lignocellulosic-based biofuels with special focus on designing more efficient metabolic pathways coupled with screening, and engineering of novel enzymes. Graphical Abstract
15 citations
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TL;DR: This paper reviews process parameters and their fundamental modes of action for promising pretreatment methods and concludes that pretreatment processing conditions must be tailored to the specific chemical and structural composition of the various, and variable, sources of lignocellulosic biomass.
6,110 citations
TL;DR: In this paper, a review of cost effective technologies and the processes to convert biomass into useful liquid bio-fuels and bioproducts, with particular focus on some biorefinery concepts based on different feedstocks aiming at the integral utilization of these feedstocks for the production of value added chemicals.
Abstract: Sustainable economic and industrial growth requires safe, sustainable resources of energy. For the future re-arrangement of a sustainable economy to biological raw materials, completely new approaches in research and development, production, and economy are necessary. The ‘first-generation’ biofuels appear unsustainable because of the potential stress that their production places on food commodities. For organic chemicals and materials these needs to follow a biorefinery model under environmentally sustainable conditions. Where these operate at present, their product range is largely limited to simple materials (i.e. cellulose, ethanol, and biofuels). Second generation biorefineries need to build on the need for sustainable chemical products through modern and proven green chemical technologies such as bioprocessing including pyrolysis, Fisher Tropsch, and other catalytic processes in order to make more complex molecules and materials on which a future sustainable society will be based. This review focus on cost effective technologies and the processes to convert biomass into useful liquid biofuels and bioproducts, with particular focus on some biorefinery concepts based on different feedstocks aiming at the integral utilization of these feedstocks for the production of value added chemicals.
2,814 citations
TL;DR: Lignin is the generic term for a large group of aromatic polymers resulting from the oxidative combinatorial coupling of 4-hydroxyphenylpropanoids, deposited predominantly in the walls of secondarily thickened cells, making them lignin-like polymers.
Abstract: Lignin is the generic term for a large group of aromatic polymers resulting from the oxidative combinatorial coupling of 4-hydroxyphenylpropanoids ([Boerjan et al., 2003][1]; [Ralph et al., 2004][2]). These polymers are deposited predominantly in the walls of secondarily thickened cells, making them
1,956 citations
TL;DR: In this article, a detailed review has been conducted to highlight different related aspects to the biodiesel industry, including, biodiesel feedstocks, extraction and production methods, properties and qualities of biodiesel, problems and potential solutions of using vegetable oil, advantages and disadvantages of biodies, the economical viability and finally the future of the future biodiesel.
Abstract: As the fossil fuels are depleting day by day, there is a need to find out an alternative fuel to fulfill the energy demand of the world. Biodiesel is one of the best available resources that have come to the forefront recently. In this paper, a detailed review has been conducted to highlight different related aspects to biodiesel industry. These aspects include, biodiesel feedstocks, extraction and production methods, properties and qualities of biodiesel, problems and potential solutions of using vegetable oil, advantages and disadvantages of biodiesel, the economical viability and finally the future of biodiesel. The literature reviewed was selective and critical. Highly rated journals in scientific indexes were the preferred choice, although other non-indexed publications, such as Scientific Research and Essays or some internal reports from highly reputed organizations such as International Energy Agency (IEA), Energy Information Administration (EIA) and British Petroleum (BP) have also been cited. Based on the overview presented, it is clear that the search for beneficial biodiesel sources should focus on feedstocks that do not compete with food crops, do not lead to land-clearing and provide greenhouse-gas reductions. These feedstocks include non-edible oils such as Jatropha curcas and Calophyllum inophyllum , and more recently microalgae and genetically engineered plants such as poplar and switchgrass have emerged to be very promising feedstocks for biodiesel production. It has been found that feedstock alone represents more than 75% of the overall biodiesel production cost. Therefore, selecting the best feedstock is vital to ensure low production cost. It has also been found that the continuity in transesterification process is another choice to minimize the production cost. Biodiesel is currently not economically feasible, and more research and technological development are needed. Thus supporting policies are important to promote biodiesel research and make their prices competitive with other conventional sources of energy. Currently, biodiesel can be more effective if used as a complement to other energy sources.
1,496 citations
TL;DR: The inhibitory effect on ethanol production by yeast and bacteria is presented and the inhibition of volumetric ethanol productivity was found to depend on the amount of methoxyl substituents and hence hydrophobicity (log P).
Abstract: An overview of the different inhibitors formed by pre-treatment of lignocellulosic materials and their inhibition of ethanol production in yeast and bacteria is given. Different high temperature physical pre-treatment methods are available to render the carbohydrates in lignocellulose accessible for ethanol fermentation. The resulting hydrolyzsates contain substances inhibitory to fermentation—depending on both the raw material (biomass) and the pre-treatment applied. An overview of the inhibitory effect on ethanol production by yeast and bacteria is presented. Apart from furans formed by sugar degradation, phenol monomers from lignin degradation are important co-factors in hydrolysate inhibition, and inhibitory effects of these aromatic compounds on different ethanol producing microorganisms is reviewed. The furans and phenols generally inhibited growth and ethanol production rate (QEtOH) but not the ethanol yields (YEtOH) in Saccharomyces cerevisiae. Within the same phenol functional group (aldehyde, ketone, and acid) the inhibition of volumetric ethanol productivity was found to depend on the amount of methoxyl substituents and hence hydrophobicity (log P). Many pentose-utilizing strains Escherichia coli, Pichia stipititis, and Zymomonas mobilis produce ethanol in concentrated hemicellulose liquors but detoxification by overliming is needed. Thermoanaerobacter mathranii A3M3 can grow on pentoses and produce ethanol in hydrolysate without any need for detoxification.
1,427 citations