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Biotechnology for Biofuels

James J Lischeske, Nathan C Crawford, Erik Kuhn, Nicholas J Nagle, Daniel J Schell, Melvin P Tucker, James D McMillan, Edward J Wolfrum
BACKGROUND: Pretreatment is a critical step in the biochemical conversion of lignocellulosic biomass to fuels and chemicals. Due to the complexity of the physicochemical transformations involved, predictively scaling up technology from bench- to pilot-scale is difficult. This study examines how pretreatment effectiveness under nominally similar reaction conditions is influenced by pretreatment reactor design and scale using four different pretreatment reaction systems ranging from a 3 g batch reactor to a 10 dry-ton/days continuous reactor...
2016: Biotechnology for Biofuels
Whitney D Hollinshead, Sarah Rodriguez, Hector Garcia Martin, George Wang, Edward E K Baidoo, Kenneth L Sale, Jay D Keasling, Aindrila Mukhopadhyay, Yinjie J Tang
BACKGROUND: Glycolysis breakdowns glucose into essential building blocks and ATP/NAD(P)H for the cell, occupying a central role in its growth and bio-production. Among glycolytic pathways, the Entner Doudoroff pathway (EDP) is a more thermodynamically favorable pathway with fewer enzymatic steps than either the Embden-Meyerhof-Parnas pathway (EMPP) or the oxidative pentose phosphate pathway (OPPP). However, Escherichia coli do not use their native EDP for glucose metabolism. RESULTS: Overexpression of edd and eda in E...
2016: Biotechnology for Biofuels
Jiangshan Ma, Keke Zhang, Mei Huang, Stanton B Hector, Bin Liu, Chunyi Tong, Qian Liu, Jiarui Zeng, Yan Gao, Ting Xu, Ying Liu, Xuanming Liu, Yonghua Zhu
BACKGROUND: Lignocellulolytic bacteria have revealed to be a promising source for biofuel production, yet the underlying mechanisms are still worth exploring. Our previous study inferred that the highly efficient lignocellulose degradation by bacterium Pantoea ananatis Sd-1 might involve Fenton chemistry (Fe(2+) + H2O2 + H(+) → Fe(3+) + OH· + H2O), similar to that of white-rot and brown-rot fungi. The aim of this work is to investigate the existence of this Fenton-based oxidation mechanism in the rice straw degradation process of P...
2016: Biotechnology for Biofuels
Kwang Soo Shin, Sangwoo Kim, Sung Kuk Lee
BACKGROUND: Microbial production of oleochemicals has been actively studied in the last decade. Free fatty acids (FFAs) could be converted into a variety of molecules such as industrial products, consumer products, and fuels. FFAs have been produced in metabolically engineered Escherichia coli cells expressing a signal sequence-deficient acyl-CoA thioesterase I ('TesA). Nonetheless, increasing the expression level of 'TesA seems not to be an appropriate approach to scale up FFA production because a certain ratio of each component including fatty acid synthase and 'TesA is required for optimal production of FFAs...
2016: Biotechnology for Biofuels
Simón Menendez-Bravo, Julia Roulet, Martín Sabatini, Santiago Comba, Robert Dunn, Hugo Gramajo, Ana Arabolaza
BACKGROUND: Microbial synthesis of oleochemicals derived from native fatty acid (FA) metabolism has presented significant advances in recent years. Even so, native FA biosynthetic pathways often provide a narrow variety of usually linear hydrocarbons, thus yielding end products with limited structural diversity. To overcome this limitation, we took advantage of a polyketide synthase-based system from Mycobacterium tuberculosis and developed an Escherichia coli platform with the capacity to synthesize multimethyl-branched long-chain esters (MBE) with novel chemical structures...
2016: Biotechnology for Biofuels
Yunpeng Wang, Lei Chen, Weiwen Zhang
BACKGROUND: 3-hydroxypropionic acid (3-HP) is an important platform chemical with a wide range of applications. In our previous study, the biosynthetic pathway of 3-HP was constructed and optimized in cyanobacterium Synechocystis sp. PCC 6803, which led to 3-HP production directly from CO2 at a level of 837.18 mg L(-1) (348.8 mg/g dry cell weight). As the production and accumulation of 3-HP in cells affect cellular metabolism, a better understanding of cellular responses to 3-HP synthesized internally in Synechocystis will be important for further increasing 3-HP productivity in cyanobacterial chassis...
2016: Biotechnology for Biofuels
Martinus J A Daas, Antonius H P van de Weijer, Willem M de Vos, John van der Oost, Richard van Kranenburg
BACKGROUND: Due to the finite nature of global oil resources we are now faced with the challenge of finding renewable resources to produce fuels and chemicals in the future. Lactic acid has great potential as a precursor for the production of bioplastics alternatives to conventional plastics. Efficient lactic acid fermentation from non-food lignocellulosic substrates requires pretreatment and saccharification to generate fermentable sugars. A fermentation process that requires little to no enzyme additions, i...
2016: Biotechnology for Biofuels
Xiujun Zhang, Yinbo Qu, Yuqi Qin
BACKGROUND: Heterochromatin protein 1 (HP1, homologue HepA in Penicillium oxalicum) binding is associated with a highly compact chromatin state accompanied by gene silencing or repression. HP1 loss leads to the derepression of gene expression. We investigated HepA roles in regulating cellulolytic enzyme gene expression, as an increasingly number of studies have suggested that cellulolytic enzyme gene expression is not only regulated by transcription factors, but is also affected by the chromatin status...
2016: Biotechnology for Biofuels
Zhen Chen, Dehua Liu
As an inevitable by-product of the biofuel industry, glycerol is becoming an attractive feedstock for biorefinery due to its abundance, low price and high degree of reduction. Converting crude glycerol into value-added products is important to increase the economic viability of the biofuel industry. Metabolic engineering of industrial strains to improve its performance and to enlarge the product spectrum of glycerol biotransformation process is highly important toward glycerol biorefinery. This review focuses on recent metabolic engineering efforts as well as challenges involved in the utilization of glycerol as feedstock for the production of fuels and chemicals, especially for the production of diols, organic acids and biofuels...
2016: Biotechnology for Biofuels
María Ángeles Bermúdez Alcántara, Justyna Dobruchowska, Parastoo Azadi, Bruno Díez García, Fernando P Molina-Heredia, Francisco Manuel Reyes-Sosa
BACKGROUND: To reduce the cost of the enzymes for the hydrolysis of lignocellulosic biomass, two main strategies have been followed: one, the reduction of enzyme dosing by the use of more efficient and stable enzymatic cocktails; another, to include accessory enzymes in the cocktails to increase yields by reducing the recalcitrant carbohydrate fraction remaining at the end of the process. To guide this second strategy, we have explored the chemical bond composition of different fractions of recalcitrant carbohydrates after enzymatic hydrolysis...
2016: Biotechnology for Biofuels
Thaila Fernanda Dos Reis, Pollyne Borborema Almeida de Lima, Nádia Skorupa Parachin, Fabiana Bombonato Mingossi, Juliana Velasco de Castro Oliveira, Laure Nicolas Annick Ries, Gustavo Henrique Goldman
BACKGROUND: The conversion of lignocellulosic biomass to biofuels (second-generation biofuel production) is an environmentally friendlier alternative to petroleum-based energy sources. Enzymatic deconstruction of lignocellulose, catalyzed by filamentous fungi such as Aspergillus nidulans, releases a mixture of mono- and polysaccharides, including hexose (glucose) and pentose (xylose) sugars, cellodextrins (cellobiose), and xylooligosaccharides (xylobiose). These sugars can subsequently be fermented by yeast cells to ethanol...
2016: Biotechnology for Biofuels
Shuai Zhao, Yu-Si Yan, Qi-Peng He, Lin Yang, Xin Yin, Cheng-Xi Li, Li-Chun Mao, Lu-Sheng Liao, Jin-Qun Huang, Shang-Bo Xie, Qing-Dong Nong, Zheng Zhang, Lei Jing, Ya-Ru Xiong, Cheng-Jie Duan, Jun-Liang Liu, Jia-Xun Feng
BACKGROUND: The filamentous fungus Penicillium oxalicum is a potential alternative to Trichoderma reesei for industrial production of a complete cellulolytic enzyme system for a bio-refinery. Comparative omics approaches can support rational genetic engineering and/or breeding of filamentous fungi with improved cellulase production capacity. In this study, comparative genomic, transcriptomic and secretomic profiling of P. oxalicum HP7-1 and its cellulase and xylanase hyper-producing mutant EU2106 were employed to screen for novel regulators of cellulase and xylanase gene expression...
2016: Biotechnology for Biofuels
Sun Young Choi, Hyun Jeong Lee, Jaeyeon Choi, Jiye Kim, Sang Jun Sim, Youngsoon Um, Yunje Kim, Taek Soon Lee, Jay D Keasling, Han Min Woo
BACKGROUND: Metabolic engineering of cyanobacteria has enabled photosynthetic conversion of CO2 to value-added chemicals as bio-solar cell factories. However, the production levels of isoprenoids in engineered cyanobacteria were quite low, compared to other microbial hosts. Therefore, modular optimization of multiple gene expressions for metabolic engineering of cyanobacteria is required for the production of farnesyl diphosphate-derived isoprenoids from CO2. RESULTS: Here, we engineered Synechococcus elongatus PCC 7942 with modular metabolic pathways consisting of the methylerythritol phosphate pathway enzymes and the amorphadiene synthase for production of amorpha-4,11-diene, resulting in significantly increased levels (23-fold) of amorpha-4,11-diene (19...
2016: Biotechnology for Biofuels
Ceren Alkim, Debora Trichez, Yvan Cam, Lucie Spina, Jean Marie François, Thomas Walther
BACKGROUND: Glycolic acid (GA) is a two-carbon hydroxyacid with applications in the cosmetic, textile, and medical industry. Microbial GA production from all sugars can be achieved by engineering the natural glyoxylate shunt. The synthetic (d)-xylulose-1 phosphate (X1P) pathway provides a complementary route to produce GA from (d)-xylose. The simultaneous operation of the X1P and glyoxylate pathways increases the theoretical GA yield from xylose by 20 %, which may strongly improve GA production from hemicellulosic hydrolysates...
2016: Biotechnology for Biofuels
Olivia A Thompson, Gary M Hawkins, Steven W Gorsich, Joy Doran-Peterson
BACKGROUND: Lignocellulosic biomass continues to be investigated as a viable source for bioethanol production. However, the pretreatment process generates inhibitory compounds that impair the growth and fermentation performance of microorganisms such as Saccharomyces cerevisiae. Pinewood specifically has been shown to be challenging in obtaining industrially relevant ethanol titers. An industrial S. cerevisiae strain was subjected to directed evolution and adaptation in pretreated pine biomass and resultant strains, GHP1 and GHP4, exhibited improved growth and fermentative ability on pretreated pine in the presence of related inhibitory compounds...
2016: Biotechnology for Biofuels
Mikako Tachioka, Naohisa Sugimoto, Akihiko Nakamura, Naoki Sunagawa, Takuya Ishida, Taku Uchiyama, Kiyohiko Igarashi, Masahiro Samejima
BACKGROUND: Random mutagenesis is a powerful technique to obtain mutant proteins with different properties from the wild-type molecule. Error-prone PCR is often employed for random mutagenesis in bacterial protein expression systems, but has rarely been used in the methylotrophic yeast Pichia pastoris system, despite its significant advantages, mainly because large (μg-level) amounts of plasmids are required for transformation. RESULTS: We developed a quick and easy technique for random mutagenesis in P...
2016: Biotechnology for Biofuels
Zhiguo Liu, Wei Liao, Yan Liu
BACKGROUND: Animal wastes are of particular environmental concern due to greenhouse gases emissions, odor problem, and potential water contamination. Anaerobic digestion (AD) is an effective and widely used technology to treat them for bioenergy production. However, the sustainability of AD is compromised by two by-products of the nutrient-rich liquid digestate and the fiber-rich solid digestate. To overcome these limitations, this paper demonstrates a biorefinery concept to fully utilize animal wastes and create a new value-added route for animal waste management...
2016: Biotechnology for Biofuels
Liqun Jiang, Nannan Wu, Anqing Zheng, Zengli Zhao, Fang He, Haibin Li
BACKGROUND: Fermentable sugars are important intermediates in the biological conversion of biomass. Hemicellulose and amorphous cellulose are easily hydrolyzed to fermentable sugars in dilute acid, whereas crystalline cellulose is more difficult to be hydrolyzed. Cellulose fast pyrolysis is an alternative method to liberate valuable fermentable sugars from biomass. The amount of levoglucosan generated from lignocellulose by fast pyrolysis is usually lower than the theoretical yield based on the cellulose fraction...
2016: Biotechnology for Biofuels
Mike Robert Allwright, Adrienne Payne, Giovanni Emiliani, Suzanne Milner, Maud Viger, Franchesca Rouse, Joost J B Keurentjes, Aurélie Bérard, Henning Wildhagen, Patricia Faivre-Rampant, Andrea Polle, Michele Morgante, Gail Taylor
BACKGROUND: Second generation (2G) bioenergy from lignocellulosic feedstocks has the potential to develop as a sustainable source of renewable energy; however, significant hurdles still remain for large-scale commercialisation. Populus is considered as a promising 2G feedstock and understanding the genetic basis of biomass yield and feedstock quality are a research priority in this model tree species. RESULTS: We report the first coppiced biomass study for 714 members of a wide population of European black poplar (Populus nigra L...
2016: Biotechnology for Biofuels
R Adam Thompson, Sanjeev Dahal, Sergio Garcia, Intawat Nookaew, Cong T Trinh
BACKGROUND: Clostridium thermocellum is a gram-positive thermophile that can directly convert lignocellulosic material into biofuels. The metabolism of C. thermocellum contains many branches and redundancies which limit biofuel production, and typical genetic techniques are time-consuming. Further, the genome sequence of a genetically tractable strain C. thermocellum DSM 1313 has been recently sequenced and annotated. Therefore, developing a comprehensive, predictive, genome-scale metabolic model of DSM 1313 is desired for elucidating its complex phenotypes and facilitating model-guided metabolic engineering...
2016: Biotechnology for Biofuels
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