Improved ethanol yield and reduced Minimum Ethanol Selling Price (MESP) by modifying low severity dilute acid pretreatment with deacetylation and mechanical refining: 1) Experimental

Chen, Xiaowen; Tao, Ling; Shekiro, Joseph; Mohaghaghi, Ali; Decker, Steve R.; Wang, Weiwei; Smith, Hilary; Park, Sunkyu; Himmel, Michael E.; Tucker, Melvin P.

doi:10.1186/1754-6834-5-60

Cited by 69 publications

(67 citation statements)

References 22 publications

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“…2A, p-coumaric acid, ferulic acid, and glucose all led to mcl-PHA accumulation in P. putida at comparable levels, namely 34-39% cell dry weight (cdw). Acetate, which is quite prevalent in APL due to deacetylation of hemicellulose side chains in caustic conditions (28), is the exception, with only 20% cdw production of mcl-PHAs ( Fig. 2A).…”

Section: Resultsmentioning

confidence: 99%

Lignin valorization through integrated biological funneling and chemical catalysis

Linger

Vardon

Guarnieri

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

715

630

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Lignin is an energy-dense, heterogeneous polymer comprised of phenylpropanoid monomers used by plants for structure, water transport, and defense, and it is the second most abundant biopolymer on Earth after cellulose. In production of fuels and chemicals from biomass, lignin is typically underused as a feedstock and burned for process heat because its inherent heterogeneity and recalcitrance make it difficult to selectively valorize. In nature, however, some organisms have evolved metabolic pathways that enable the utilization of lignin-derived aromatic molecules as carbon sources. Aromatic catabolism typically occurs via upper pathways that act as a "biological funnel" to convert heterogeneous substrates to central intermediates, such as protocatechuate or catechol. These intermediates undergo ring cleavage and are further converted via the β-ketoadipate pathway to central carbon metabolism. Here, we use a natural aromatic-catabolizing organism, Pseudomonas putida KT2440, to demonstrate that these aromatic metabolic pathways can be used to convert both aromatic model compounds and heterogeneous, lignin-enriched streams derived from pilot-scale biomass pretreatment into medium chain-length polyhydroxyalkanoates (mcl-PHAs). mcl-PHAs were then isolated from the cells and demonstrated to be similar in physicochemical properties to conventional carbohydratederived mcl-PHAs, which have applications as bioplastics. In a further demonstration of their utility, mcl-PHAs were catalytically converted to both chemical precursors and fuel-range hydrocarbons. Overall, this work demonstrates that the use of aromatic catabolic pathways enables an approach to valorize lignin by overcoming its inherent heterogeneity to produce fuels, chemicals, and materials. biofuels | lignocellulose | biorefinery | aromatic degradation

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Section: Resultsmentioning

confidence: 99%

Lignin valorization through integrated biological funneling and chemical catalysis

Linger

Vardon

Guarnieri

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

715

630

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“…One strategy is to improve pretreatment and hydrolysis processes using less severe conditions to increase sugar contents while reducing the inhibitor concentrations. Recently, a highly efficient deacetylation and mechanical refining (DMR) process has been developed resulting in low toxicity and high concentration of mixed sugars that are superior for ethanol production by Z. mobilis (Chen et al 2012. Another strategy is to develop robust Z. mobilis strains with enhanced ethanol productivity in the presence of hydrolysate inhibitors.…”

Section: Discussionmentioning

confidence: 99%

Progress and perspective on lignocellulosic hydrolysate inhibitor tolerance improvement in Zymomonas mobilis

Yang

Tang

et al. 2018

Bioresour. Bioprocess.

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Pretreatment is the key step to overcome the recalcitrance of lignocellulosic biomass making sugars available for subsequent enzymatic hydrolysis and microbial fermentation. During the process of pretreatment and enzymatic hydrolysis as well as fermentation, various toxic compounds may be generated with strong inhibition on cell growth and the metabolic capacity of fermenting strains. Zymomonas mobilis is a natural ethanologenic bacterium with many desirable industrial characteristics, but it can also be severely affected by lignocellulosic hydrolysate inhibitors. In this review, analytical methods to identify and quantify potential inhibitory compounds generated during lignocellulose pretreatment and enzymatic hydrolysis were discussed. The effect of hydrolysate inhibitors on Z. mobilis was also summarized as well as corresponding approaches especially the high-throughput ones for the evaluation. Then the strategies to enhance inhibitor tolerance of Z. mobilis were presented, which include both forward and reverse genetics approaches such as classical and novel mutagenesis approaches, adaptive laboratory evolution, as well as genetic and metabolic engineering. Moreover, this review provided perspectives and guidelines for future developments of robust strains for efficient bioethanol or biochemical production from lignocellulosic materials.

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“…The use of dilute alkaline deacetylation combined with low acid pretreatment process steps has shown improvements in ethanol yields and calculated MESP for cellulosic ethanol production [27,28]. Acetyl groups in the hemicellulose are liberated and removed as acetic acid by sodium hydroxide during deacetylation, greatly reducing inhibition from acetate to improve hydrolysis and fermentation performance (in the context of ethanol production; implications for hydrocarbon production are noted below).…”

Section: Overviewmentioning

confidence: 99%

Process Design and Economics for the Conversion of Lignocellulosic Biomass to Hydrocarbons: Dilute-Acid and Enzymatic Deconstruction of Biomass to Sugars and Biological Conversion of Sugars to Hydrocarbons

Davis¹,

Tao²,

Tan³

et al. 2013

307

569

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The U.S. Department of Energy (DOE) promotes the production of a range of liquid fuels and fuel blendstocks from lignocellulosic biomass feedstocks by funding fundamental and applied research that advances the state of technology in biomass collection, conversion, and sustainability. As part of its involvement in this program, the National Renewable Energy Laboratory (NREL) investigates the conceptual production economics of these fuels.Between 1999 and 2012, NREL conducted a campaign to quantify the economic implications associated with measured conversion performance for the biochemical production of cellulosic ethanol, with a formal program between 2007-2012 to set cost goals and to benchmark annual performance toward achieving these goals, namely the pilot-scale demonstration by 2012 of biochemical ethanol production at a price competitive with petroleum gasoline based on modeled assumptions for an "n th " plant biorefinery. This goal was successfully achieved through NREL's 2012 pilot plant demonstration runs, representing the culmination of NREL research focused specifically on cellulosic ethanol, and a benchmark for industry to leverage as it commercializes the technology. This important milestone also represented a transition toward a new Program focus on infrastructure-compatible hydrocarbon biofuel pathways, and the establishment of new research directions and cost goals across a number of potential conversion technologies.This report describes in detail one potential conversion process to hydrocarbon products by way of biological conversion of lignocellulosic-derived sugars. The pathway model leverages expertise established over time in core conversion and process integration research at NREL, while adding in new technology areas primarily for hydrocarbon production and associated processing logistics. The overarching process design converts biomass to a hydrocarbon intermediate, represented here as a free fatty acid, using dilute-acid pretreatment, enzymatic saccharification, and bioconversion. Ancillary areas-feed handling, hydrolysate conditioning, product recovery and upgrading (hydrotreating) to a final blendstock material, wastewater treatment, lignin combustion, and utilities-are also included in the design. Detailed material and energy balances and capital and operating costs for this baseline process are also documented.This benchmark case study techno-economic model provides a production cost for a cellulosic renewable diesel blendstock (RDB) that can be used as a baseline to assess its competitiveness and market potential. It can also be used to quantify the economic impact of individual conversion performance targets and prioritize these in terms of their potential to reduce cost. The analysis presented here also includes consideration of the life-cycle implications of the baseline process model, by tracking sustainability metrics for the modeled biorefinery, including greenhouse gas (GHG) emissions, fossil energy demand, and consumptive water use.Building on prior design reports for bioch...

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Improved ethanol yield and reduced Minimum Ethanol Selling Price (MESP) by modifying low severity dilute acid pretreatment with deacetylation and mechanical refining: 1) Experimental

Cited by 69 publications

References 22 publications

Lignin valorization through integrated biological funneling and chemical catalysis

Lignin valorization through integrated biological funneling and chemical catalysis

Progress and perspective on lignocellulosic hydrolysate inhibitor tolerance improvement in Zymomonas mobilis

Process Design and Economics for the Conversion of Lignocellulosic Biomass to Hydrocarbons: Dilute-Acid and Enzymatic Deconstruction of Biomass to Sugars and Biological Conversion of Sugars to Hydrocarbons

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