Industry Takes Another Look at Biomass 

New Policies Encourage Growth Of Technology 

Genetic Engineering News v.21, n.5, 1mar01

Gail Dutton

In an effort to help stimulate biomass research and development among biotech firms, the Biotechnology Industry Organization (BIO; Washington, D.C.) is developing new bio-based policy proposals for the Bush Administration and Congress. Unlike the Clinton Administration's plans to stimulate the biomass industry, the BIO initiative addresses two key factors necessary to make biomass successful: the development of more effective enzymes and the construction of large-scale biorefineries.

"Recent increases in gasoline, home heating oil and natural gas prices have made everyone aware of how critical it is for us to develop new sources of energy," says Brent Erickson, director of BIO's industrial and environmental biotechnology section. "BIO member companies are using genetic research to produce enzymes that will convert abundant agricultural biomass into fuels, plastics and other bio-based products:"

Biomass Conversion

Biomass conversion has been gaining ground since the 1980s, but it is just now beginning to become commercially feasible. For example, the U.S. Department of Energy (DOE) and the U.S. Department of Agriculture have allocated about $250 million for biomass projects, according to lack Huttner, chair, of the Biomass R&D technical advisory council and vp, corporate communications and public affairs, at Genencor International Inc. (Rochester, NY).

The reason for such interest, asserts Pat McCroskey, Ph.D., senior director of business development for Diversa Corp. (San Diego), is a convergence of improved proteomics data, new enhancement techniques borrowed from drug discovery and a strong agricultural lobby.

"There is an opportunity to take cheap raw materials and convert them to useful monomers that are combined to make longer chained polymers that are used downstream to make ethanol or other products," he says.

Specifically, it is becoming possible to design highly effective enzymes that have the potential of reducing enzyme costs by tenfold.

"Enzyme technology is a key part of the equation," Erickson insists. "But, we also must build biorefineries that are fully integrated industrial facilities capable of transforming not just corn, but the cellulosic biomass, into a full range of products. We can learn from the petroleum industry"

If renewable feedstock is to be an economic reality, that will encourage the development of plants that are engineered to support biorefineries. That means genetically engineered plants, for example, that may contain higher than normal sugar or starch content, or that actually make plastics precursors within their stalks.

Fuel production is only one of a myriad of possible products that can be produced from biomass. For instance, scientists at Genencor International in Palo Alto, CA, are using a $17 million NREL grant awarded April 2000 to develop routes to low-cost fermentable sugars.

More recently, it has licensed

technology from Protein Polymer Technologies Inc. (San Diego) to advance beyond ethanol to use biomass as the feedstock in a wide range of products that includes high performance fibers, electronic chips, optical switches and other nanomaterials.

Improved Enzymes

Enzyme improvement typically focuses on target recognition, control mechanisms and actions.

"To bring [improved enzymes] to market, Genencor is developing techniques for expressing proteins with cost/benefit ratios commensurate with industrial uses, and thereby can make bio-based materials to serve a market," explains Karl Sanford, Ph.D., VP of technology development.

Currently, the goal is to develop enzymes with improved expression systems and higher specific activity that will provide a 10-fold improvement when compared to existing commercial enzymes. This work is part of a $16 million award from NREL/DOE to Genencor last June.

The company already has demonstrated some success. A 1999 venture with DuPont (Wilmington, DE) yielded a 500-fold improvement in productivity by combining enzymes from two different microorganisms into one production strain to produce a 1,3 propanediol (3G or PDO), a monomer that enhances the stretch-recovery properties of a type of polyester known as 3GT.

Likewise, a joint project with Eastman Chemical Company (Kingsport, TN) yielded a totally aqueous process for making ascorbic acid from glucose that removed several steps from the traditional chemical synthesis of vitamin C.

Its work with Protein Polymer Technologies holds the promise of creating novel materials and new functionalities for existing materials. The process to create those materials owes much to the predictive capabilities of protein folding when using repeat protein motifs, thus allowing the design template to take on a more defined structure, Dr. Sanford explains: "We're building on 18 years of work to build a biomaterial development platform."

Enzyme Efficiency

Novozymes Biotech, Inc (Davis, CA) in January won a $14.8 million, three-year contract from the DOE to develop high efficiency enzymes to lower the costs of converting biomass into fermentable sugars that, in turn, will be converted into ethanol bio-based products.

To be efficient, "enzyme costs need to be about 5 cents per gallon of ethanol produced," says Glenn Nedwin, Novozymes' president, citing research conducted at the National Renewable Energy Laboratory (Golden, CO). Today, he says, enzyme costs are about 45 cents per gallon of ethanol.

The process uses much of the technology used in drug discovery: protein expression assays, microarrays, proteomics, fermentation research, high throughput screening, and high level gene expression, Nedwin says. The issue is that those technologies are very expensive.

Costs can be recouped in drug development, which tends to yield high-end pharmaceuticals. When the product is a commodity chemical, however, it becomes cost effective only with external funding, like that provided by the DOE.

The goal is to convert more of the cellulose in corn stover and, eventually, rice straw, bagasse, wood chips, and paper into glucose. Additionally, about 15% of the cellulose to glucose conversion in corn starch processing is wasted.

The other big issue relates to the feedstock itself, Nedwin says. Specifically, "The collection and transportation of the biomass to be converted will be costly. A successful process will likely require the construction of a local ethanol plant near the biomass collection site."

Diversa is at the planning stages, looking at green waste and paper waste development options. There is a good chance the company will concentrate upon paper waste because the infrastructure to collect it is already in place through paper recycling centers, and because of the glut of waste paper in the U.S. "Corn doesn't have that advantage," Dr. McCroskey says.

Companies, in general, are aiming for a 10-fold improvement in enzyme efficiency, but, according to Dr. McCroskey, a 100-fold increase is needed to make biomass conversion viable. The traditional route towards such improvements is to go to the environment to discover new enzymes, he says, but, "less than 0.1 % of those enzymes can be duplicated in the lab:'

Diversa, in contrast, is engineering enzymes for specific conditions, in the same the way drugs are engineered.

"We take a sample-from Yellowstone National Park, for example-and extract all of the DNA. That's 5,000 to 10,000 organisms and billions of genes per sample," says Dr. McCroskey.

"We create DNA libraries and develop assays, for the desired characteristics, screening one billion genes per day." At that point, Diversa can begin to modify the molecular structure of the enzymes.

Modifying Diversity

"Once we identify a protein, we [have the option to] change each of the 20 known amino acids, looking at all possible changes to increase its stability," he says. Changing each amino acid is an option; gene reassembly is another.

Diversa also is beginning to explore the whole-cell method of catalyst development. Traditionally, industrial processes isolate enzymatic reactions into multistep synthesis. The whole-cell method allows that multistep process to occur in one step, by combining the relevant enzymes in a single cell.

The key, of course, is to choose enzymes that don't inhibit necessary reactions. "If you can overcome that, the whole-cell method is more effective and may offer commodity pricing," Dr. McCroskey says. "This isn't ready for commercialization," he adds.

Diversa currently is working with Celanese Ltd. (Corpus Christi, TX) for whole-cell optimization opportunities for commodity and specialty chemical applications.

Cargill Dow 11c (Minnetonka, MN) expects to finish construction this year on its bio-based, polylactide manufacturing facility in Blair, NE. The plant will use corn as the initial feedstock but any starch could be used, according to Michael O'Brien, communications director. Cargill Dow is focusing on improving the fermentation process, but results are highly proprietary.

Each of these enzyme enhancement projects builds upon years of research but, ultimately, success may depend as much upon distribution systems and logistics as it does good science. As Dr. Sanford notes, "Biomass includes quite a bit of material-bark, leaves, corn stalks, etc."

Eventually, Dr. McCroskey adds, it may include transgenic plants that have no value except for their cellulose (e.g., plants that are more than 80% cellulose, or plants that produce the final product themselves). Whatever types of plants are used, says Dr. Stanford, "We need to have a conception of materials in local geographies. Therefore, corn is a likely first candidate for biomass conversion plants."