New Approaches in Cellulosic Biomass to Fuels and Chemicals
ID: 3926

Abstract: Susan Leschine

At present, biomass is the only source of liquid transportation fuels that may replace the world's finite supply of oil. Cellulosic ethanol derived from non-food biomass, such as woodchips, switchgrass, and agricultural by-products, is one of the most promising advanced biofuels with major environmental and national security benefits in the form of reduced greenhouse gas emissions and decreased dependence on imported oil. Development of the cellulosic biofuels industry will promote rural growth and create jobs throughout the economy, thus forming a key component of the Green Economy of the future.

Cellulosic ethanol is derived from solar energy captured by photosynthesis and stored in the form of plant biomass. The positive energy return on investment for cellulosic ethanol production results, at least in part, from the fact that the process makes use of the whole plant. However, the recalcitrance of cellulosic biomass to enzymatic processing and the scarcity of effective microbial catalysts capable of fermenting the wide range of carbohydrates found in biomass pose significant impediments to the development of commercially viable technologies for cellulosic ethanol production. To overcome these obstacles, Qteros Inc. is focused on a microbial bioprocessing technology known as Complete Cellulose Conversion (C3), which employs a novel bacterium from forest soil, a strain of Clostridium phytofermentans known as the Q Microbe™. This bacterium possesses exceptional nutritional versatility. It decomposes all fermentable components of biomass, including the hemicellulosic portion, and produces ethanol as its primary fermentation product. Recently, the complete genome sequence of this unique microbial catalyst was determined. Gene expression microarray experiments based on the genome sequence have confirmed the importance of ethanol production in the overall metabolism of the microbe. Additionally, the Q Microbe adjusts its metabolism and the production of degradative enzymes in response to growth substrate. Facile adaptation of metabolism to different feedstocks is a major strength of the C3 technology, allowing the use of mild and environmentally friendly procedures for feedstock pretreatment. The properties of the Q Microbe indicate that it is an ideal organism for use in the C3 process, a biomass conversion scheme in which production of the cellulase enzymes, cellulose decomposition, and fermentation are all consolidated in a single step. The Q Microbe-C3 technology eliminates the need for costly enzymes and simplifies the entire ethanol production process yielding significant economic advantages.



Mai Petersen

Inbicon A/S (a DONG Energy subsidiary) has been operating a large-scale pilot plant (100-1000 kg/h) for the conversion of wheat straw to ethanol since 2005. The focus in process development has been on sustainability and energy efficiency. Therefore all process steps are carried out at high dry matter content (above 25 % water insoluble solids) and without addition of chemicals. To further increase energy efficiency the production of bioethanol is integrated with a power plant.

The process converts cellulose into bioethanol. Lignin is converted into a high-quality solid biofuel which supply the process energy as well as a surplus of heat and power. Hemicellulose is used as a feed molasses but could in the future also be used for additional ethanol production or other valuable products.

At the moment a 4 t/h demonstration plant is constructed. The plant will demonstrate the process from pretreatment of the wheat straw via hydrolysis and SSF to distillation of the ethanol and production of feed molasses and solid biofuel. The biorefinery is going to be inaugurated ultimo 2009 in connection with the United Nations Climate Change Conference 2009 in Copenhagen, Denmark (COP15).

This presentation describes the new demonstration plant, the development of the process and the advantages and challenges of working at high dry matter.



Hideaki Yukawa

In this era of dwindling supplies of cheaply exploitable fossil fuel resources and increased general awareness of the serious implications that fossil fuel-fueled climate change may engender, multi-pronged efforts to promote a shift away from the finite fossil fuel resources are underway. Of these, the biorefinery concept encompasses technologies through which energy and commodity chemicals can be produced from renewable biomass resources. It employs microbial activity on biomass resources in conversion processes that are not very dissimilar to current chemical refineries. Subject to enhanced productivity, the concept’s effect on current fuel and/or commodity chemical production infrastructure could be so significant as to spring an industrial revolution of the 21st century. Biorefinery-related R&D has progressed dramatically as a result of recent advancements in the field of biotechnology, with industry in Japan embracing the concept as a novel basis on which the establishment of a new industry is possible.

Existing bioethanol production processes, based on corn and soy beans, have increased acreage of the crops grown for biofuels, resulting in increased food prices. Moreover, inefficiencies inherent in current corn-based bioethanol production mean that they not only cannot satisfy the growing demand for bioethanol, but their effect on the environment may not be positive. There is therefore a need to develop tomorrow’s production technology, in which bioethanol is produced from cellulosic biomass. The new technology must be high-yielding, capable of simultaneous utilization of pentose and hexose sugars, and resistant to fermentation inhibitors derived from lignocellulose degradation.

The RITE bioprocess is based on a novel concept that enables highly efficient production of a variety of biochemicals using microbial cells whose growth is artificially arrested. In essence, the growth-arrested, genetically modified Corynebacterium glutamicum cells used in the bioprocess function like inorganic catalysts of chemical processes. It is, therefore, possible to fill a reactor to a high density with microbial cells and continuously supply the biomass-derived substrates (sugars) to the reactor to carry out the reaction at high speed. As a result, productivity (space time yield; STY) of the RITE bioprocess is much higher than that of conventional bioprocesses and is comparable to that of chemical processes. In contrast, the productivity of conventional bioprocesses is microbial growth-dependent, implying significantly lower STY compared to chemical processes. In most biorefinery-related R&D, microbial functions can be radically improved through advances in post-genome technology; however, there is a limit as to how much of the costs arising from microbial cell growth can be lowered. By being growth-independent, the RITE bioprocess avoids such limitations, making chemicals and energy production using the bioprocess highly economically viable.

In collaboration with Honda R&D Co. Ltd., we aim for early industrial application of the RITE bioprocess in bioethanol production. A pilot plant built in the premises of Honda R&D Co. Ltd. will enable us to get the engineering data necessary for industrialization.

In this presentation, our current studies on biofuel production will be discussed.



Christopher Voigt

We have been working on two inventions. The first is the development of a yeast fermentation to convert biomass to methyl halides (methyl chloride, methyl bromide, and methyl iodide). Using zeolite based catalysts, this building block molecule can be cheaply converted to commodity chemicals (benzene, toluene, xylene, ethylene, propylene, methanol, DME), as well as liquid fuels (gasoline, TMB). The catalysts have existed since the early 1970s. For example, ZSM-5 is used to convert methyl halides to gasoline. Using tools from Synthetic Biology, we have developed a strain of yeast that can produce 200 mg/L-hr of methyl iodide from sugar. We can also produce high yields of methyl chloride and methyl bromide.

In a second project, we have developed a co-culture system for cellulose degradation that utilizes both a yeast and a bacterium. The bacterium is able to eat relevant sources of biomass, including switchgrass, poplar, corn stover, and bagasse and is unique in that most of the carbon is excreted in the form of acetate and ethanol. These metabolites can then be consumed by a yeast, which then produces the desired product. There is a double negative feedback loop in this synthetic symbiotic relationship, which stabilizes the populations in a fermentation. We have demonstrated that this system can produce high titers of methyl halide from switchgrass, poplar, bagasse, and corn stover.









Moderator: Kevin Gray, Qteros (United States)

Presenter 1: The IBUS process - Demonstration of a biorefinery working at very high dry matter
Mai Petersen, Inbicon A/S, (Denmark)  [Confirmed]

Presenter 2: Biofuel/Commodity chemical Production by Simultaneous Utilization of Mixed Sugars 
Hideaki Yukawa, RITE, (Japan)  [Confirmed]

Presenter 3: Methyl Halide Production in Bacteria and Yeast 
Christopher Voigt, UCSF, (United States)  [Confirmed]

Presenter 4 (if necessary): Complete Cellulosic Conversion of Biomass to Ethanol in a Single Step Process 
Susan Leschine, Qteros, (United States)  [Confirmed]

Panel Organizer:
Matthew Carr, Biotechnology Industry Organization, (United States)

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