scholarly journals Improved ethanol yield and reduced minimum ethanol selling price (MESP) by modifying low severity dilute acid pretreatment with deacetylation and mechanical refining: 2) Techno-economic analysis

2012 ◽  
Vol 5 (1) ◽  
pp. 69 ◽  
Author(s):  
Ling Tao ◽  
Xiaowen Chen ◽  
Andy Aden ◽  
Eric Kuhn ◽  
Michael E Himmel ◽  
...  
Keyword(s):  
Economic Analysis ◽  
Ethanol Yield ◽  
Dilute Acid Pretreatment ◽  
Selling Price ◽  
Dilute Acid ◽  
Acid Pretreatment ◽  
Mechanical Refining ◽  
Minimum Ethanol Selling Price

scholarly journals Genetic Engineering of Enterobacter asburiae Strain JDR-1 for Efficient Production of Ethanol from Hemicellulose Hydrolysates

2009 ◽  
Vol 75 (18) ◽  
pp. 5743-5749 ◽  
Author(s):  
Changhao Bi ◽  
Xueli Zhang ◽  
Lonnie O. Ingram ◽  
James F. Preston
Keyword(s):  
Ethanol Yield ◽  
Maximum Yield ◽  
Pyruvate Decarboxylase ◽  
Dry Weight ◽  
Dilute Acid Pretreatment ◽  
Efficient Production ◽  
Dilute Acid ◽  
Acid Pretreatment ◽  
Acid Fermentation ◽  
Enterobacter Asburiae

ABSTRACT Dilute acid pretreatment is an established method for hydrolyzing the methylglucuronoxylans of hemicellulose to release fermentable xylose. In addition to xylose, this process releases the aldouronate methylglucuronoxylose, which cannot be metabolized by current ethanologenic biocatalysts. Enterobacter asburiae JDR-1, isolated from colonized wood, was found to efficiently ferment both methylglucuronoxylose and xylose in acid hydrolysates of sweet gum xylan, producing predominantly ethanol and acetate. Transformation of E. asburiae JDR-1 with pLOI555 or pLOI297, each containing the PET operon containing pyruvate decarboxylase (pdc) and alcohol dehydrogenase B (adhB) genes derived from Zymomonas mobilis, replaced mixed-acid fermentation with homoethanol fermentation. Deletion of the pyruvate formate lyase (pflB) gene further increased the ethanol yield, resulting in a stable E. asburiae E1(pLOI555) strain that efficiently utilized both xylose and methylglucuronoxylose in dilute acid hydrolysates of sweet gum xylan. Ethanol was produced from xylan hydrolysate by E. asburiae E1(pLOI555) with a yield that was 99% of the theoretical maximum yield and at a rate of 0.11 g ethanol/g (dry weight) cells/h, which was 1.57 times the yield and 1.48 times the rate obtained with the ethanologenic strain Escherichia coli KO11. This engineered derivative of E. asburiae JDR-1 that is able to ferment the predominant hexoses and pentoses derived from both hemicellulose and cellulose fractions is a promising subject for development as an ethanologenic biocatalyst for production of fuels and chemicals from agricultural residues and energy crops.

scholarly journals Understanding the effects of different residual lignin fractions in acid-pretreated bamboo residues on its enzymatic digestibility

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Wenqian Lin ◽  
Jinlai Yang ◽  
Yayue Zheng ◽  
Caoxing Huang ◽  
Qiang Yong
Keyword(s):  
Enzymatic Hydrolysis ◽  
Negative Impact ◽  
Dilute Acid Pretreatment ◽  
Residual Lignin ◽  
Dilute Acid ◽  
Enzymatic Digestibility ◽  
Acid Pretreatment ◽  
Organic Reagents ◽  
Milled Wood Lignin ◽  
Affinity Constants

Abstract Background During the dilute acid pretreatment process, the resulting pseudo-lignin and lignin droplets deposited on the surface of lignocellulose and inhibit the enzymatic digestibility of cellulose in lignocellulose. However, how these lignins interact with cellulase enzymes and then affect enzymatic hydrolysis is still unknown. In this work, different fractions of surface lignin (SL) obtained from dilute acid-pretreated bamboo residues (DAP-BR) were extracted by various organic reagents and the residual lignin in extracted DAP-BR was obtained by the milled wood lignin (MWL) method. All of the lignin fractions obtained from DAP-BR were used to investigate the mechanism for interaction between lignin and cellulase using surface plasmon resonance (SPR) technology to understand how they affect enzymatic hydrolysis Results The results showed that removing surface lignin significantly decreased the yield for enzymatic hydrolysis DAP-BR from 36.5% to 18.6%. The addition of MWL samples to Avicel inhibited its enzymatic hydrolysis, while different SL samples showed slight increases in enzymatic digestibility. Due to the higher molecular weight and hydrophobicity of MWL samples versus SL samples, a stronger affinity for MWL (KD = 6.8–24.7 nM) was found versus that of SL (KD = 39.4–52.6 nM) by SPR analysis. The affinity constants of all tested lignins exhibited good correlations (r > 0.6) with the effects on enzymatic digestibility of extracted DAP-BR and Avicel. Conclusions This work revealed that the surface lignin on DAP-BR is necessary for maintaining enzyme digestibility levels, and its removal has a negative impact on substrate digestibility.

scholarly journals A Process Study of Lactic Acid Production from Phragmites australis Straw by a Thermophilic Bacillus coagulans Strain under Non-Sterilized Conditions

Processes ◽  
2018 ◽  
Vol 6 (10) ◽  
pp. 175 ◽  
Author(s):  
Yuming Zhang ◽  
Mengran Li ◽  
Tian Nie ◽  
Zhihua Ni
Keyword(s):  
Lactic Acid ◽  
Phragmites Australis ◽  
Lactic Acid Production ◽  
Scale Up ◽  
Bacillus Coagulans ◽  
Dilute Acid Pretreatment ◽  
Integrated Process ◽  
Dilute Acid ◽  
Acid Pretreatment ◽  
Process Study

Phragmites australis straw (PAS) is an abundant and renewable wetland lignocellulose. Bacillus coagulans IPE22 is a robust thermophilic strain with pentose-utilizing capability and excellent resistance to growth inhibitors. This work is focused on the process study of lactic acid (LA) production from P. australis lignocellulose which has not been attempted previously. By virtue of thermophilic feature of strain IPE22, two fermentation processes (i.e., separated process and integrated process), were developed and compared under non-sterilized conditions. The integrated process combined dilute-acid pretreatment, hemicellulosic hydrolysates fermentation, and cellulose utilization. Sugars derived from hemicellulosic hydrolysates and cellulose enzymatic hydrolysis were efficiently fermented to LA in a single vessel. Using the integrated process, 41.06 g LA was produced from 100 g dry PAS. The established integrated process results in great savings in terms of time and labor, and the fermentation process under non-sterilized conditions is easy to scale up for economical production of lactic acid from PAS.

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