Agave: The Elixir for Parties and Biofuel?

 

Thu, 10/08/2015 - 10:03am Greg Watry, Digital Reporter Image: T photography/Shutterstock.com Famous for its role in tequila and mezcal production, the agave plant was worshipped by Mexico’s natives long before the Spaniards arrived in the 15th century. The Aztec goddess Mayheul was closely associated with agave, a symbol for life, health, dance and fertility. According to the International Organic Agave Alliance, archeological findings date the plants usage back some 10,000 years. But the broad-leafed, spiky plant may have more use than just supplying a bottle of spirits for a wild weekend revelry. Researchers from the Australian Research Council Centre of Excellence in Plant Cell Walls released a study in PLOS ONE touting the plant as a potential source for biofuel. “Bioethanol yields from agave fermentation could rival the most successful biofuel feedstock crops around the world,” said co-author Prof. Rachel Burton, of the Univ. of Adelaide’s School of Agriculture, Food and Wine. “Importantly, it doesn’t compete with food crops; it’s fast growing so the whole plant could be used rather than just harvesting the leaves; and it is up to 10 times more water efficient than some other crop plants.” Studying Agave americana and Agave tequilana, the researchers found use of the former could yield 4,000 to 13,600 L/ha/yr, and the latter, 4,400 to 14,800 L/ha/yr. If the whole plant is used, that is. Even at the low end, the values surpass theoretical yields from first-generation feedstocks, such as corn, wheat and sugarcane, according to the researchers. The high values double yields from recently investigated biofuel sources, such as poplar, sorghum and switchgrass. Tequila and mezcal are made from the stem tissue of Agave tequilana when the plants are between eight and 12 years old. When heated, the stem tissues release fermentable fructose. However, the leftover leaves, which the researchers say accounts for 66% of the biomass, is discarded. “Waste leaves could generate up to (8,000 L/ha/yr) and increase profit from the agave crop, or, if directly separating and fermenting the juice was more economically viable, up to 4,000 (L/ha/yr) is achievable,” said Burton. Research is in progress to find the best cultivation methods for bioethanol production.   http://www.rdmag.com/articles/2015/10/agave-elixir-parties-and-biofuel

Mould unlocks new route to biofuels

 

Structure of enzymes for hydrocarbons. Credit: Image courtesy of Manchester University Scientists at The University of Manchester have made an important discovery that forms the basis for the development of new applications in biofuels and the sustainable manufacturing of chemicals. Based at the Manchester Institute of Biotechnology (MIB), researchers have identified the exact mechanism and structure of two key enzymes isolated from yeast moulds that together provide a new, cleaner route to the production of hydrocarbons. Published in Nature, the research offers the possibility of replacing the need for oil in current industrial processes with a greener and more sustainable natural process. Lead investigator Professor David Leys, explains the importance of his work: "One of the main challenges our society faces is the dwindling level of oil reserves that we not only depend upon for transport fuels, but also plastics, lubricants, and a wide range of petrochemicals. Solutions that seek to reduce our dependency on fossil oil are urgently needed." He adds: "Whilst the direct production of fuel compounds by living organisms is an attractive process, it is currently not one that is well understood, and although the potential for large-scale biological hydrocarbon production exists, in its current form it would not support industrial application, let alone provide a valid alternative to fossil fuels." Professor Leys and his team investigated in detail the mechanism whereby common yeast mould can produce kerosene-like odours when grown on food containing the preservative sorbic acid. They found that these organisms use a previously unknown modified form of vitamin B2 (flavin) to support the production of volatile hydrocarbons that caused the kerosene smell. Their findings also revealed the same process is used to support synthesis of vitamin Q10 (ubiquinone). Using the Diamond synchrotron source at Harwell, they were able to provide atomic level insights into this bio catalytic process, and reveal it shares similarities with procedures commonly used in chemical synthesis but previously thought not to occur in nature. Professor David Leys says: "Now that we understand how yeast and other microbes can produce very modest amounts of fuel-like compounds through this modified vitamin B2-dependent process, we are in a much better position to try to improve the yield and nature of the compounds produced." In this particular study, published in the journal Nature, researchers focussed on the production of alpha-olefins; a high value, industrially crucial intermediate class of hydrocarbons that are key chemical intermediates in a variety of applications, such as flexible and rigid packaging and pipes, synthetic lubricants used in heavy duty motor and gear oils, surfactants, detergents and lubricant additives. Professor Leys concludes: "This fundamental research builds on the MIB's expertise in enzyme systems and provides the basis for the development of new applications in biofuel and commodity chemical production. The insights from this research offer the possibility of circumventing current industrial processes which are reliant on scarce natural resources." Story Source: The above post is reprinted from materials provided by Manchester University. Note: Materials may be edited for content and length. Journal Reference: Karl A. P. Payne, Mark D. White, Karl Fisher, Basile Khara, Samuel S. Bailey, David Parker, Nicholas J. W. Rattray, Drupad K. Trivedi, Royston Goodacre, Rebecca Beveridge, Perdita Barran, Stephen E. J. Rigby, Nigel S. Scrutton, Sam Hay, David Leys. New cofactor supports α,β-unsaturated acid decarboxylation via 1,3-dipolar cycloaddition. Nature, 2015; DOI: 10.1038/nature14560

Food and fuel: model for bioenergy feedstock/vegetable double-cropping systems

 

Much attention has been given to dedicated, perennial bioenergy crops to meet the revised Renewable Fuel Standard mandating production of 36 billion gallons of biofuel by the year 2022. Even so, concern remains over the impending need to convert as much as 30 million acres of U.S. crop land, which would include food crops, to land for perennial energy crops in order to meet that demand. Researchers realize that biomass feedstocks will need to come from many different sources, including crop residues, forest residues, and municipal waste, for example, said Marty Williams, a University of Illinois crop scientist and ecologist with the USDA-Agricultural Research Service. The use of double-cropping systems--a winter annual biomass crop is grown then harvested in the spring, followed by a summer annual crop--has been suggested as an additional option. Knowing that many large-seeded vegetables in the Midwest must be planted later than agronomic crops into warmer soils, Williams was interested in the possibility of developing a bioenergy feedstock/vegetable double-cropping system. He explained that no such system had been developed and tested yet. "Some vegetables have relatively short growing seasons, too. Rather than the standard fallow period for certain vegetables, what about integrating a bioenergy crop as a part of a double-cropping system?" Williams said. Williams chose a vegetable crop popular in the state of Illinois, pumpkin, to be used in the double-cropping system study. "We took a fairly simplistic look at comparing this bioenergy/vegetable double-cropping system with traditional vegetable production using processing pumpkin," Williams explained. "Illinois leads the nation in pumpkin production, providing some 90 percent of the processing pumpkin in the United States." Field trials were conducted over three environments. During the study, Williams compared crop productivity and weed communities in four different pumpkin production systems, varying in tillage, cover crop, and bioenergy feedstock/pumpkin double-cropping. A fall-planted rye (Secale cereale) mix was used as the biomass feedstock. "In the end, winter rye may not be the best feedstock crop to use," he explained. "It was more of a model crop for us for our system. It grows well and has several desirable traits. Seed is relatively inexpensive and the plant is hardy." Interestingly, the researchers saw pumpkin yields in the double-cropping system were comparable to conventional pumpkin production. However, the biomass feedstock also yielded an average of 4.4 tons per acre of dry biomass prior to pumpkin planting. "We saw a theoretical yield of 349 gallons of ethanol per acre, and a higher farm gate value than typical pumpkin production," Williams said. "It looks promising," he added. "The biomass yield wasn't as high as something like Miscanthus, but we're producing feedstock and not taking land away from food production. Moreover, the cropping systems were not optimized, such as for soil fertility, so our economic estimates are likely conservative." Overall, the biomass yield was comparable to that of 'Shawnee' switchgrass, but only one-half the yield of a hybrid switchgrass, the study reported. "Perhaps some of our vegetable-cropping systems could contribute to bioenergy production, while still producing veggies," Williams said. "Also, there may be certain vegetable crops that are better suited to double-cropping. Given the potential competition between food and fuel production globally, systems making contributions towards both goals appear worth further consideration," he added. Story Source: The above story is based on materials provided by University of Illinois College of Agricultural, Consumer and Environmental Sciences. The original article was written by Stephanie Henry. Note: Materials may be edited for content and length. Journal Reference: Martin M. Williams. A bioenergy feedstock/vegetable double-cropping system. Industrial Crops and Products, 2014; 59: 223 DOI: 10.1016/j.indcrop.2014.05.025

Novel pretreatment could cut biofuel costs by 30 percent or more

This is a diagram of a proposed biomass conversion process that integrates CELF pretreatment with Simultaneous Saccharification Fermentation to produce ethanol. Researchers at the University of California, Riverside have invented a novel pretreatment technology that could cut the cost of biofuels production by about 30 percent or more by dramatically reducing the amount of enzymes needed to breakdown the raw materials that form biofuels. As partners in the BioEnergy Science Center (BESC), the team from the Bourns College of Engineering Department of Chemical and Environmental Engineering and Center for Environmental Research and Technology (CE-CERT) have shown that this new operation called Co-solvent Enhanced Lignocellulosic Fractionation (CELF) could eliminate about 90 percent of the enzymes needed for biological conversion of lignocellulosic biomass to fuels compared to prior practice. This development could mean reducing enzyme costs from about $1 per gallon of ethanol to about 10 cents or less. The BioEnergy Science Center is a U.S. Department of Energy Bioenergy Research Center focused on enhancing science and technology to reduce the cost of biomass conversion through support by the Office of Biological and Environmental Research in the Department of Energy Office of Science.. "As recent months have shown, petroleum prices are inherently unstable and will likely return to high prices soon as expensive sources are taken off line," said Professor Charles Wyman, the Ford Motor Company Chair in Environmental Engineering at UC Riverside. "We have created a transformative technology that has the potential to make biofuels an economic sustainable alternative to petroleum-based fuels." The findings by Wyman's research group were outlined in a just published paper, "Co-solvent Pretreatment Reduces Costly Enzyme Requirements for High Sugar and Ethanol Yields from Lignocellulosic Biomass," in the journal ChemSusChem. Co-authors with Wyman are: Thanh Yen Nguyen, Charles M. Cai, and Rajeev Kumar, all of whom are students or research engineers in Wyman's lab. Research by the Wyman team focuses on turning agricultural and forestry residues and other non-edible plant matter, known as lignocellulosic biomass, into liquid transportation fuels. Lignocellulosic biomass is attractive because it is sustainable and abundant and inexpensive compared to oil. For example, lignocellulosic biomass costing about $60?a dry ton is equivalent in unit energy costs to oil at about $20?barrel. (Oil is currently selling for about $55 a barrel but has hovered around the $100 per barrel mark in recent years.) The challenge is to lower the cost of processing low cost biomass sources into fuels. Lignocellulosic biomass is composed of hemicellulose, cellulose, and lignin, and biological processes favored for making liquid biofuels convert the hemicellulose and cellulose into sugars that can in turn be fermented into biofuels. However, the complex structure of lignocellulosic biomass makes it difficult for enzymes to release these sugars, and a pretreatment step using heat and chemicals is needed to reduce this recalcitrance enough to realize the high yields vital to economic success. The lignin left in biomass after most pretreatments presents a particular problem by impeding enzyme access to hemicellulose and cellulose, thereby hurting product yields and requiring more enzyme at a substantial cost. CELF, the pretreatment developed at UC Riverside, solves those problems. In the ChemSusChem paper, the UC Riverside researchers outline laboratory results in which they compared the total achievable combined sugar yields between CELF pretreatment and dilute acid pretreatment, a current leading strategy, coupled with subsequent enzymatic hydrolysis in three timeframes with three levels of enzymes. Using the dilute acid method, the sugar yield was only about 70 percent of the maximum possible after 14 days when two milligrams of enzymes were used. That percentage increased to about 85 percent in 14 days when 15 milligrams of enzymes were added. By contrast, CELF pretreatment increased sugar yields to about 95 percent of the maximum possible regardless of whether two milligrams, five milligrams, or 15 milligrams of enzymes were added. Furthermore, the time required to reach these high yields dropped to five days when five milligrams of enzyme were used and two days when 15 milligrams of enzyme were used. In addition to such drastic cutting of the amount and cost of enzymes needed to realize nearly theoretical sugar yields, CELF is capable of dissolving and extracting up to 90 percent of the lignin in corn stover and even more for woody biomass. After pretreatment and enzymes release of the sugars from hemicellulose and cellulose, previous process strategies have focused on burning the residual lignin, which is a low value proposition. However, lignin has promise as a resource from which to make additional high value chemicals and fuels once it is extracted and depolymerized with CELF. "These findings are very significant because they establish a new pretreatment process that can dramatically reduce enzyme loadings and costs, thereby improving the competitiveness for biological conversion of lignocellulosic biomass to fuels," said Wyman, who has focused on understanding and advancing biofuels technologies for more than 30 years. "Understanding the mechanisms responsible for achieving these intriguing results can also suggest even more powerful paths to improving the economics of converting non-edible biomass into sustainable fuels."

Toward the next biofuel: Secrets of Fistulifera solaris

 

February 2, 2015 American Society of Plant Biologists Biofuels are an attractive alternative to fossil fuels, but a key challenge in efforts to develop carbon-neutral, large-scale methods to produce biofuels is finding the right organism for the job. One emerging candidate is the microalga Fistulifera solaris. An international collaboration of scientists has revealed the genome of F. solaris and provided exciting hints at the roots of its ability to grow and produce oil at the same time. Biofuels made from plant-produced oils are an attractive alternative to fossil fuels. However, the enormous amount of arable land needed for production and the competition between their uses as food/feed and fuel present obstacles to the production of biofuels from crops. These considerations have led to focus on microalgae as oil producers. Microalgae are tiny photosynthetic organisms found in both ocean water and freshwater. They grow quickly in liquid culture and can produce high levels of oils. In fact, the omega-3 fatty acids present in fish are actually produced by microalgae that are eaten by the fish. Institutions throughout the world have generated collections of wild microalgae in efforts to find species with desirable characteristics. One such microalga is a species of diatom called Fistulifera solaris, which is emerging as a promising candidate for next-generation biofuel technology. Diatoms are microscopic algae that are major contributors to marine ecosystems; they are also the basis of diatomaceous earth, which is used by gardeners as a natural pest deterrent. Not only does F. solaris grow quickly and produce high levels of oils, it does both at the same time, unlike other oil-producing microalgae that produce their highest amounts of oil at stages when they grow slowly, if at all. These characteristics make F. solaris an excellent candidate for batch culture (see figure) to produce biomass from which oil for biofuels can be harvested. F. solaris was originally isolated from samples taken at the junction of two rivers in Japan. A collaboration of scientists in Japan and France aimed to elucidate the molecular underpinnings of simultaneous growth and oil production by sequencing the genome of F. solaris and also cataloguing the transcriptome -- providing a read-out of all genes expressed at a given time. Lead scientist Dr. Tsuyoshi Tanaka of the Division of Biotechnology and Life Science in the Institute of Engineering at Tokyo University of Agriculture and Technology, highlights the need for this information, saying "Biofuel production using photosynthetic organisms such as microalgae is one of the most promising approaches to generating sustainable energy. However, the molecular functions of organisms such as oleaginous microalgae remain unclear, thus hampering efforts to improve productivity." Tokyo University of Agriculture and Technology. Story Source: The above story is based on materials provided by American Society of Plant Biologists. Note: Materials may be edited for content and length. Journal Reference: Tsuyoshi Tanaka, Yoshiaki Maeda, Alaguraj Veluchamy, Michihiro Tanaka, Heni Abida, Eric Maréchal, Chris Bowler, Masaki Muto, Yoshihiko Sunaga, Masayoshi Tanaka, Tomoko Yoshino, Takeaki Taniguchi, Yorikane Fukuda, Michiko Nemoto, Mitsufumi Matsumoto, Pui Shan Wong, Sachiyo Aburatani, Wataru Fujibuchi. Oil Accumulation by the Oleaginous DiatomFistulifera solarisas Revealed by the Genome and Transcriptome. The Plant Cell Online, 2015; tpc.114.135194 DOI: 10.1105/tpc.114.135194

Sweet Smell of Success: JBEI Researchers Boost Methyl Ketone Production in E. coli

 

Lynn Yarris - December 1, 2014 Methyl ketones were discovered more than a century ago in the aromatic evergreen rue plant. They are now used to provide scents in essential oils and flavoring in cheese, but JBEI research shows they could also serve as advanced biofuels. (Image from Wikimedia Commons) Two years ago, researchers at the U.S. Department of Energy’s Joint BioEnergy Institute (JBEI) engineered Escherichia coli (E. coli) bacteria to convert glucose into significant quantities of methyl ketones, a class of chemical compounds primarily used for fragrances and flavors, but highly promising as clean, green and renewable blending agents for diesel fuel. Now, after further genetic modifications, they have managed to dramatically boost the E.coli’s methyl ketone production 160-fold. “We’re encouraged that we could make such a large improvement in methyl ketone production with a relatively small number of genetic modifications,” says Harry Beller, a JBEI microbiologist who led this study. “We believe we can further improve production using the knowledge gained from in vitro studies of our novel metabolic pathway.” Beller, who directs the Biofuels Pathways department for JBEI’s Fuels Synthesis Division, and is also a senior scientist with Berkeley Lab’s Earth Sciences Division, is the corresponding author of a paper describing this work in the journal Metabolic Engineering. The paper is titled “Substantial improvements in methyl ketone production in E. coli and insights on the pathway from in vitro studies.” Co-authors are Ee-Been Goh, Edward Baidoo, Helcio Burd, Taek Soon Lee and Jay Keasling. Methyl ketones are naturally occurring compounds discovered more than a century ago in the aromatic evergreen plant known as rue. Since then they’ve been found to be common in tomatoes and other plants, as well as insects and microorganisms. Today they are used to provide scents in essential oils and flavoring in cheese and other dairy products. Although native E. coli make virtually undetectable quantities of methyl ketones, Beller, co-author Goh and their colleagues have been able to overcome this deficiency using the tools of synthetic biology. The research of Harry Beller (foreground) and Ee-Been Goh of the Joint BioEnergy Institute is boosting the production of methyl ketones by engineered strains of E.coli. (Photo by Roy Kaltschmidt, Berkeley Lab) “In our original effort, for methyl ketone production we made two major modifications to E. coli,” Beller says. “First we modified specific steps in beta-oxidation, the metabolic pathway that E. coli uses to break down fatty acids, and then we increased the expression of a native E. coli enzyme called FadM. These two modifications combined to greatly enhance the production of methyl ketones.” In their latest effort, Beller, Goh and their colleagues made further modifications that included balancing the overexpression of two other E. coli enzymes, fadR and fadD, to increase fatty acid flux into the pathway; consolidating two plasmid pathways into one; optimizing codon usage for pathway genes not native to E. coli; and knocking out key acetate production pathways. The results led to a methyl ketone titer of 3.4 grams/liter after approximately 45 hours of fed-batch fermentation with glucose. This is about 40-percent of the maximum theoretical yield for methyl ketones. “Although the improved production is still not at a commercial level in the biofuel market, it is near a commercial level for use in flavor and fragrances, where certain methyl ketones are much more highly valued than they would be in the biofuel market,” Beller says. “It may be possible for a company to sell a small percentage of methyl ketones in the flavor and fragrance market and use the profits to enhance the economic viability of the production of methyl ketones as biofuels.” The in vitro studies carried out by Beller and Goh provided insights into the pathway, some of which point to even further production gains. One key finding was the confirmation that a decarboxylase enzyme is not required for this methyl ketone pathway. “Several different metabolic pathways have been developed in the past couple of years for methyl ketone production in E. coli, a couple of which use decarboxylase enzymes to catalyze the last step of the pathway,” Beller says. “Our methyl ketone pathway is performing quite a bit better than these other pathways, but it does not include a native or added decarboxylase.” The in vitro studies also addressed concerns about the FadM enzyme being somewhat “promiscuous” in its hydrolyzing (thioesterase) activities. Beller and Goh found that FadM can act on intermediates in the methyl ketone pathway and effectively reduce the flux of carbon to the final methyl ketone products. However, they say that with some informed metabolic engineering, this need not be a problem and knowledge of the phenomenon could even be used to enhance production. “In all likelihood, there is a sweet spot in the level of expression of the FadM enzyme that will allow for maximal production of methyl ketones without siphoning away metabolic intermediates,” Beller says. This research was supported by JBEI through the U.S. Department of Energy’s Office of Science. Additional Information For more information about Harry Beller and his research go here For more information about JBEI go here JBEI is one of three Bioenergy Research Centers established by the DOE’s Office of Science in 2007. It is a scientific partnership led by Berkeley Lab and includes the Sandia National Laboratories, the University of California campuses of Berkeley and Davis, the Carnegie Institution for Science, and the Lawrence Livermore National Laboratory. DOE’s Bioenergy Research Centers support multidisciplinary, multi-institutional research teams pursuing the fundamental scientific breakthroughs needed to make production of cellulosic biofuels, or biofuels from nonfood plant fiber, cost-effective on a national scale. Lawrence Berkeley National Laboratory addresses the world’s most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab’s scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy’s Office of Science. For more, visit www.lbl.gov. source of this article : www.lbl.gov.

The biomethane market needs clear frame conditions for further growth, experts urge

 

September 11, 2014

Helmholtz Centre For Environmental Research - UFZ

Biomethane as a substitute for the fossil energy carrier natural gas offers a variety of options and applications for a sustainable energy supply. Nevertheless, a consequent market penetration is still pending because of a lack of standardized and transnational frame conditions. Scientists have now summarized how the biomethane market developed in the IEA (International Energy Agency) member states and which factors are necessary for further growing.

---

According to the report around 280 biogas upgrading plants in different countries with a production capacity of around 100,000 Nm³/h of biomethane are already in operation.

Biomethane as a substitute for the fossil energy carrier natural gas offers a variety of options and applications for a sustainable energy supply. Nevertheless, a consequent market penetration is still pending because of a lack of standardized and transnational frame conditions. Scientists of the Helmholtz Centre for Environmental Research (UFZ) and the German Biomass Research Centre (DBFZ) and other Members of the IEA Task 37 (Energy from Biogas) and the Task 40 (Sustainable Bioenergy Trade) just summarized how the biomethane market developed in the IEA (International Energy Agency) member states and which factors are necessary for further growing.

In most of the IEA member states the fossil energy carrier natural gas still plays an important and increasing role in the national energy supply. This is due to a well-developed infrastructure of gas networks, gas stations, and various modes of transportation by e.g. vessels. However, mainly due to the significantly lower greenhouse gas emissions, the energy security and the protection of finite resources, several countries initiated support programs for biomethane (methane from biomass). This is due to a well-developed infrastructure of gas networks, gas stations, and various modes of transport by tanker trucks or ships. Still have, mainly due to the significantly lower greenhouse gas emissions, energy security and the protection of finite resources already several countries initiated the gradual transition from fossil natural gas resource on renewable energy sources biomethane (methane from biomass).

The newly published study "Biomethane -- status and factors affecting market development and trade," gives an up-to-date and comprehensive overview of the production technologies of biomethane (upgrading of biogas and Bio-SNG), the grid injection and the use in various IEA member states. Moreover, besides the description of the framework, the options and needs for the development of larger biomethane supply strategies are also illustrated. The authors finalize the study with concrete recommendations how the remaining barriers can be removed and the market development can be promoted step by step.

Greenhouse gas reduction potential of more than 80 percent

Due to the benefits (i) independence from natural gas imports, (ii) the strengthening of rural areas, (iii) and its promising application areas (fuel, cogeneration, heat), biomethane is considered as a promising alternative to fossil fuels. As far as the final composition of the biomethane is consistent with the various natural gas quality levels in the market it can serve as a substitute for natural gas. In addition, biomethane can also be transported and stored as natural gas. Last but not least, greenhouse gas emissions, depending on the plant design and operation as well as the accounting method, can be reduced in comparison to fossil fuels by more than 80 percent. The study already stated a transnational increasing interest in biomethane. According to the report around 280 biogas upgrading plants in different countries with a production capacity of around 100,000 Nm³/h of biomethane are already in operation.

Transnational frame conditions are required

A transnational biomethane market is, according to the study, still at the beginning. However, various strategies, investment programs, funding and utilization concepts have been adopted in the investigated countries. Due to the complex supply chain there are various ecological, economic, administrative and political barriers for a market implementation of biomethane. For a sustainable and international implementation appropriate technical standards, sustainability requirements and political as well as financial support (compensation / promotion / preference), in order to significantly advance the development of an international biomethane trade, are necessary.

Further information: http://www.bioenergytrade.org/downloads/t40-t37-biomethane-2014.pdf

---

Story Source:

The above story is based on materials provided by Helmholtz Centre For Environmental Research - UFZ. Note: Materials may be edited for content and length.

The plant that only grows when the going's good

---

Scientists have identified a new mutant plant that accumulates excessive amounts of starch, which could help to boost crop yields and increase the productivity of plants grown for biofuels.

Researchers from the Max Planck Institute of Molecular Plant Physiology looked for excessive starch accumulators in the model plant Arabidopsis thaliana that had been mutated using Agrobacterium tumefaciens. In one of the mutant plants, the starch granules were significantly larger compared to the controls. Christened NEX1 (meaning NOVEL STARCH EXCESS 1), the researchers believe that the mutation may have affected an enzyme involved in starch degradation. Alternatively, the starch granules themselves may be abnormal and resistant to being broken down for fuel.

Usually, plants that store excessive amounts of starch are much smaller, as less sucrose is available to fuel growth. Remarkably, nex1 mutants are a similar size to normal, non-mutagenised plants.

Dr Maria Grazia Annunziata, who led the study says: "In appearance, the nex1 mutant does not differ from normal plants however the starch granules are generally larger." It also appears that nex1 plants restrict their growing period to the daytime, allowing them to retain their starch reserves. Normally, plants draw on their starch reserves at night, causing the granules to shrink. In the nex1 mutant, the starch granules remain the same size throughout the night, suggesting that growth is suspended until the daytime. Combining high growth rates with large starch reserves is highly desirable for crops that are used both as silage and to feed humans, such as maize.

The researchers are currently investigating the secret of the nex1 mutant by comparing the expression of genes involved in starch metabolism in nex1 and normal plants.

This research was presented at the Society for Experimental Biology Annual Meeting 2014 held at Manchester University, UK, from the 1st - 4th of July.

Straw from oilseed as a new source of biofuels

 

May 23 / 2014

Norwich BioScience Institutes

Straw from crops such as wheat, barley, oats and oilseed rape is seen as a potential source of biomass for second generation biofuel production. Currently the UK produces around 12 million tonnes of straw. Although much is used for animal bedding, mushroom compost and energy generation, there still exists a vast surplus. Preliminary lab findings are pointing at ways that the process of turning straw from oilseed rape into biofuel could be made more efficient, as well as how the straw itself could be improved.

---

Pilot Steam Explosion Unit in the Biorefinery Centre.

The bright yellow fields of oilseed rape are a familiar sight at this time of year, but for scientists what lies beneath is just as exciting.

Researchers at the Institute of Food Research are looking at how to turn straw from oilseed rape into biofuel. Preliminary findings are pointing at ways the process could be made more efficient, as well as how the straw itself could be improved.

Straw from crops such as wheat, barley, oats and oilseed rape is seen as a potential source of biomass for second generation biofuel production. Currently the UK produces around 12 million tonnes of straw. Although much is used for animal bedding, mushroom compost and energy generation, there still exists a vast surplus.

Straw contains a mix of sugars that could be used as a source of biofuels that do not compete with food production but instead represent a sustainable way of utilizing waste. However, the sugars are in a form that makes them inaccessible to the enzymes that release them for conversion into biofuels, so pre-treatments are needed. The pre-treatments make the complex carbohydrates more accessible to enzymes that convert them to glucose, in a process called saccharification. This is then fermented by yeast into ethanol.

Using the facilities at the Biorefinery Centre on the Norwich Research Park, Professor Keith Waldron and his team have been looking at the steps needed to unlock the sugars tied up in the tough straw structure. In particular, they have looked at the pre-treatment stage, focusing on steam explosion, which involves 'pressure-cooking' the biomass, to drive a number of chemical reactions. A rapid pressure-release then causes the material to be ripped open, to further improve accessibility.

They varied the temperature and duration of steam explosion and then used a variety of physical and biochemical techniques to characterise what effects varying the pre-treatments had on the different types of sugars before and after saccharification.

The amount of cellulose converted to glucose increased with the severity of the pretreatment. Saccharification efficiency is also associated with the loss of specific sugars, and subsequent formation of sugar breakdown products.

In a further study funded by the BBSRC / EPSRC Integrated Biorefining Research and Technology Club, the scientists discovered the key factors that determine the efficiency of saccharification. One particular compound, uronic acid, limited the rate at which enzymes worked. The final sugar yield was closely related to the removal of xylan, a common component of plant cell walls. The abundance of lignin, a 'woody' cell wall component, was positively related to the amount of available sugars.

These findings will help improve the efficiency by which straw can be converted to biofuels. For example, adding enzymes that more effectively remove xylan should improve yield. Controlling the level of lignin in the material should also help.

It may even be possible to improve the straw itself, for example to reduce the uronic acid content in the biomass, as suggested by these findings. In the main, oilseed rape has been bred to improve oilseed yield and disease resistance, without paying much attention to the straw. The IFR is working with colleagues at the University of York and the John Innes Centre to see whether there are ways of breeding more "biofuel-ready" varieties of oilseed rape, with the same yields of oilseed but with more amenable straw. In addition, a full understanding of the polysaccharides and other compounds made available during pretreatment may mean other valuable co-products, like platform chemicals, may be viably produced from the surplus straw.

---

Story Source:

The above story is based on materials provided by Norwich BioScience Institutes. Note: Materials may be edited for content and length.

---

Journal References:

1. Ian P. Wood, Adam Elliston, Sam R.A. Collins, David Wilson, Ian Bancroft, Keith W. Waldron. Steam explosion of oilseed rape straw: Establishing key determinants of saccharification efficiency. Bioresource Technology, 2014; 162: 175 DOI: 10.1016/j.biortech.2014.03.115
2. Peter Ryden, Alizée Gautier, Nikolaus Wellner, Henri S. Tapp, Svein J. Horn, Vincent G.H. Eijsink, Keith W. Waldron. Changes in the composition of the main polysaccharide groups of oil seed rape straw following steam explosion and saccharification. Biomass and Bioenergy, 2014; 61: 121 DOI: 10.1016/j.biombioe.2013.12.003