Press release: http://newscenter.lbl.gov/feature-stories/2013/03/29/making-do-with-more-joint-bioenergy-institute-researchers-engineer-plant-cell-walls-to-boost-sugar-yields-for-biofuels/

News article: http://www.biofuelsjournal.com/articles/Joint_Bioenergy_Institute_Researchers_Engineer_Plant_Cell_Walls_to_Boost_Sugar_Yields_For_Biofuels-131490.html

Journal article: http://onlinelibrary.wiley.com/doi/10.1111/pbi.12016/full

Researchers at the U.S. Department of Energy (DOE)'s Joint BioEnergy Institute (JBEI) used the tools of synthetic biology to reduce the lignin content and to enhance polysaccharide deposition in cell walls of genetically engineered plants. The biomass of the engineered plants can be degraded more easily into fermentable sugars for biofuel production.

The polysaccharide sugars in plant cell walls of cellulosic feedstock like grasses and trees are locked within a tough polymer called lignin which reduces the extractability of these sugars and impedes access to degrading enzymes prior to fermentation into ethanol. In order to liberate these sugars from the lignin cage, expensive pretreatments are used. The high cost of pretreatments is a major obstacle to commercialization of cellulosic biofuels.

Reducing the lignin content in lignocellulosic biomass is not an easy feat because it may reduce biomass yield due to a consequent loss of integrity in vessels, the key tissues that transport and distribute water and nutrient from roots to the above-ground parts. In addressing the lignin problem, JBEI scientists have rewired the secondary cell network in the model plant Arabidopsis thaliana by changing the promoter for a key lignin gene. This modification disconnected the expression of the lignin gene from the fiber regulatory network and rewired the lignin biosynthesis for vessel formation. Through promoter modification the mechanism called artificial positive feedback loop (APFL) was also introduced to increase polysaccharide depositions in fibre cells. The result was a healthy engineered plant that accumulates the good stuff (polysaccharide) and reduces the problematic polymer (lignin). Compared to the non-modified plants, the engineered plants exhibited improved sugar releases from enzymatic breakdown of their biomass.

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News article: http://www.ethanolproducer.com/articles/9736/iea-publishes-global-update-of-advanced-cellulosic-projects

IEA Bioenergy Task 39 website: http://demoplants.bioenergy2020.eu/

IEA Report: http://demoplants.bioenergy2020.eu/files/Demoplants_Report_Final.pdf

The International Energy Agency Bioenergy Task 39 group recently published the report titled "Status of Advanced Biofuels Demonstration Facilities in 2012" which highlights the progress made on more than 100 advanced biofuel projects worldwide and the challenges the industry still faces.

The IEA report provides detailed descriptions of a broad range of projects including those that manufacture biofuels from lignocellulosic biomass, plant oils, sugar molecules and carbon dioxide feedstocks. Algae biomass projects are not included in the report. Analysis was conducted based on complete data gathered from 71 actively pursued advanced biofuel projects that use a variety of approaches such as biochemical, thermochemical and chemical technologies.

According to the report, lignocellulosic biofuels production has tripled since 2010 and currently accounts for approximately 140,000 metric tons of fuel per year. The report noted that companies around the world are working to develop and deploy advanced biofuel technologies that feature different feedstocks, pretreatment methods and conversion technologies to produce a variety of fuels, from cellulosic ethanol to drop-in gasoline or biobased jet fuel. Still, the industry is facing several challenges, and as expected, some projects have failed.

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Press release: http://newscenter.lbl.gov/news-releases/2013/04/07/sweet-success/

News article: http://www.ethanolproducer.com/articles/9743/berkeley-researchers-catalyze-more-sugars-from-biomass

Journal article (abstract): http://www.nature.com/nchembio/journal/vaop/ncurrent/full/nchembio.1227.html

Researchers from the University of California (UC) Berkeley and Lawrence Berkeley National Laboratory (Berkeley Lab) have developed a technique that can allow them to design better mixtures of cellulase enzymes that are optimally matched with the structure of particular biomass substrates.

The Berkeley researchers reported in the journal Nature Chemical Biology the results of their study that shed new light on the catalytic activity of cellulases, that degrade cellulosic biomass of grass and wood to release fermentable sugars into ethanol. Mixtures of cellulase enzymes are normally used because individual cellulases interact preferentially with cellulose structures based on their distinct structural organizations. Increasing the fermentable sugar yields from cellulosic biomass can boost biofuel production. A key challenge is to reduce the cost of extracting fermentable sugars by optimizing the collective activity of cellulase enzymes.

The researchers employed the technique known as PALM (Photo-Activated Localization Microscopy ) where target enzymes are tagged with molecules that emit light when activated by weak ultraviolet light. By photoactivating individual cellulase enzymes, the researchers were able to track their specific locations as they bind with the cellulose substrates. Their results showed that cellulases exhibit specificities to different cellulose structures, ranging from the highly ordered to the highly disordered. They also developed a means to show that a valuable synergy can be generated by combining cellulases that bind to similar but not identical cellulose structural organizations.

The said technique can be used to determine the optimum combination of cellulases by matching them to the structural organizations of particular biomass substrates. This will increase the efficiency of cellulose breakdown into fermentable sugar, which in turn will help reduce biofuel production costs.

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News article: http://phys.org/news/2013-04-enzymes-horse-feces-secrets-biofuel.html

Scientists from the USA have reported the isolation of a new fungal species from a horse's digestive tract  which exhibited high enzymatic activity against cellulose and lignocelluloses materials.

The enzymatic breakdown of cellulose intermeshed with the tough lignin polymer in biomass feedstock is a bottleneck in biofuel conversion. Researchers have turned to the digestive systems of large herbivores like cows and horses in search for microbial enzymes that can efficiently degrade the cellulose and lignocellulose substrates into simple sugars to be fermented into ethanol. Previous investigations have focused on gut bacteria, but researchers believe that gut fungi represent an important source of robust cellulose digesters that secrete unique and powerful enzyme complexes.

One recent study by researchers at the University of California (UC) Santa Barbara and their collaborators from the Massachusetts Institute of Technology and Harvard University focused on gut fungi living in the intestinal tracts of horses which can digest lignin-rich grasses.

In their report presented at the 245th National Meeting & Exposition of the American Chemical Society, the researchers described the isolation of a new species of anaerobic gut fungus and the subsequent discovery of novel biomass-degrading or "cellulolytic" enzymes that it produces. By analyzing the fungus's transcriptome - the collection of protein-encoding genetic material – the research team was able to directly identify and assemble the genes coding for enzymes capable of breaking down cellulose and lignocelluloses substrates. The team is now seeking to identify from this collection the most active enzymes and to transfer the fungal genes that produce such enzymes to yeasts for large-scale industrial production.

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News article: http://phys.org/news/2013-04-cost-saving-ethanol-butanola-alternative-gasoline.html

A UK research team reported the discovery of a new family of catalysts that enables highly selective conversion of ethanol into n-butanol – a more energy efficient alternative fuel for transportation.

Butanol has emerged as an advanced alternative fuel that can replace ethanol in gasoline blends because of its higher energy content and hence better fuel mileage. Recent research efforts have focused on exploring biosynthetic pathways for butanol production but these are hampered by very low conversion rates. Researchers are currently looking into catalytic processes that can upgrade more readily available ethanol to butanol. Catalysts speed up the chemical conversion by lowering the energy required to jumpstart reactions. Many ethanol producers eagerly look forward to these catalytic conversion technologies because these would require less retrofitting to produce butanol. Catalytic processes, however, are challenged by modest selectivity in most cases.

In line with this fundamental advance, University of Bristol (UK) researchers have developed homogeneous ruthenium diphosphine catalysts for upgrading ethanol to butanol, as reported at the 245th National Meeting & Exposition of the American Chemical Society. Preliminary analysis suggests that these new catalysts are better than previously used catalysts since it has selectivity to n-butanol, reaching more than 95 percent conversion. The new catalysts could reduce the cost of converting conventional ethanol plants for butanol production. With the new catalysts, the ethanol produced by conventional method could simply be upgraded to butanol with an additional reaction step.

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Press release: http://news.ucdavis.edu/search/news_detail.lasso?id=10543

Journal article: http://pubs.acs.org/doi/full/10.1021/cb300573r

Researchers at the University of California (UC), Davis have discovered several small bioactive compounds that increase oil productivity in green microscopic algae, a potential source of biodiesel and other "green" fuels. The full research paper appears online in the journal ACS Chemical Biology.

The UC Davis researchers took an approach similar to that used for therapeutic drug discovery to modulate lipid pathways in commercially viable oil-producing microalgae. This approach identified the chemical triggers for growth and oil production based on a microplate screening consisting of a pilot collection of bioactive molecules and four oleaginous microalgae strains which have been previously described as valuable for commercial biofuel applications. The lead compounds from the microplate screening were further monitored in larger cultures and the lipids produced were quantified and characterized.

The researchers identified several small molecules that significantly increased lipid productivity and may serve as promising probes of microalgae lipid pathways. Based on large culture experiments, they estimated that lipid productivity increased by up to 84 percent without decreasing the growth rate. Some of these chemical triggers would be cost-effective when scaled up to a 50,000 liter pond, according to their calculation. Among the promising compounds identified were common antioxidants such as epigallocatechin gallate, found in green tea, and butylated hydroxyanisole (BHA), a common food preservative.