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Chapter 9 and Energy production Contents

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Cellulose ...... $ ...... 240 ...... 240 ...... 241 242 245 Chapter 9 Commodity Chemicals and Energy Production —.

Introduction

In 1982, the U.S. chemical produced Practically all commodity chemicals are cur- about 158 billion pounds (lb) of organic chemicals rently made from and re- (36). About 30 commodity chemicals–defined in sources and are used as precursors for a variety this report as chemicals that sell for less than $1 of materials such as and . The per lb” —constitute the majority of this market , which now imports about 30 per- (see table 39). cent of its petroleum (34), uses about 7 to 8 per- —— cent of its total petroleum and natural gas sup- “(:h[~rnicals with higher value such as \’itamins, food additives, ii ml amino aci(L\, form the suhject of Chapter 7: Speciahv Chemicals ply for the production of commodity chemicals i]l][/ 1<’ood ,.lddifh es ‘1’he difference between “comrnodit:’” and “spc- (10,18,22); the remainder of this supply is used cialt}” chemicals is somewhat fluidlv cietermined hv prire versus as an energy source. quantities produred Some of the compounds descrihed in chapter 7 are considered by some analj~sts to be commodity chemicals. These The ’s reliance on petroleum ln(lude tcgetahle and their dcrit”atives, single cell protein, and fructose. Because of their predominant use as food additives, how- feedstocks raises a number of problems. Two e~’er, these compounds are considered in the earlier chapter. problems are the fluctuating cost and uncertain

Table 39.—Annual Production and Selling Price of the Major Organic Commodity Chemicals in the United States

Production in 1982 Price in 1982 Chemical (billion pounds) (Mb) Major uses ...... 24.7 25.5 derivatives ...... 15.3 26.7 , gas additive, solvents, polyfoams Propylene ...... 12.3 24.0 , isopropanol Ethylene dichloride ...... 10.0 13.7 Benzene ...... 7.9 21.1 , , ., ...... 7.3 10.8 ...... 6.6 30.0 Styrene Vinyl chloride ...... 6.5 22.0 , Styrene ...... 5.9 37.5 Pol yst yrenes ...... 5.3 18,9 p- and o-xylene, gas additive, ...... 5.0 N.A. ...... 4.9 45.0 Formaldehyde ...... 4.7 24.4 Resins Ethylene glycol ...... 4.0 33.0 , p-xylene ...... 3.2 31.0 Synthetic fibers ...... 2.8 26.5 Vinyl and celtulosic acetate ...... 2.7 24.0 Phenol Phenol ...... 2.1 36.0 ...... , . . . 2.0 44.5 Polymers ...... 1.9 37.5 Polyvinyl acetates, alcohols ...... 1.8 40.0 Rubber ...... 1.8 31.0 ...... 1.5 40.5 , urethanes Isopropanol ...... 1.3 32.9 Acetone, solvents Cyclohexane ...... 1.3 25.3 , caprolactum ...... 1.2 57.0 Nylon Acetic anhydride...... 1.1 41.0 Cellulose esters ...... 1.1 25.8 , solubilizer, , solvent, fuel SOURCE Office of Technology Assessment, adapted from D Webber, “Basic Chemical Output Fell Third Year in a Row,” Ctrern. Eng. News, May 2, 1983, pp. 10-13; T C O’Brien, “Feedstock Trends for the Organic Chemical Industry,” Planning Report 15, U.S. Department of Commerce, National Bureau of Standards, April 1983, and Ctrermica/ Marketing Reporter, “Weekly Price Report, ” May 31, 1982, pp. 35-39.

237 238 ● Commercial Biotechnology: An International Analysis

supplies of petroleum. Commodity chemical companies in the United States, Europe, and Japan prices are especially sensitive to the cost of may have to develop new ways of using commodi- petroleum because feedstock costs typically ty chemicals to produce compounds of greater represent 50 to 75 percent of commodity chemi- value or to move directly to the manufacture of cal costs (6). Other problems of higher value-added chemicals from biomass. In the commodity chemical industry include a cur- any case, a rapid or dramatic shift in feedstock rent overcapacity of production by the capital- use is unlikely; it is much more probable that intensive companies, the high costs there will be a slow transition to the use of of energy associated with “” petroleum biomass as a feedstock in particular instances. into chemical feedstocks, and environmental, safe- ty, and ideological concerns surrounding the use Although nonrenewable resources such as of nonrenewable, fossil resources (6). will probably be adopted earlier, biomass—includ- ing crop and forest product wastes and municipal These well-publicized problems, which increase and agricultural wastes—may provide solutions in urgency with the passing of time, have intensi- to some of the long-term problems associated with fied the search for nonpetroleum feedstocks for chemical and energy production from petroleum. chemical and energy production. The options be- It is technologically possible to produce essentially ing pursued at present include the liquification all commodity chemicals from biomass feedstocks and gasification of coal, the development of syn- such as starch or cellulose, and most commodity thetic fuel from natural gas, and the conversion chemicals can be synthesized biologically (10,24). of biomass* * to fuels and a wide variety of or- A viable biomass feedstock for the production of ganic chemicals. commodity chemicals may be starch. Less than The substitution of natural gas, coal, and other I percent of the U.S. corn crop would be required nonrenewable resources for petroleum are issues to obtain the cornstarch needed to produce a typ- that have been discussed in several previous OTA ical commodity chemical at the rate of I billion reports (28)29,31). Despite the drawbacks outlined lb per year (18). Although a few high-volume in those reports, coal is favored as an alternative chemicals that could be produced from biomass, resource by U.S. petroleum companies, which such as ethanol, can be used for fuel, the volume control 20 percent of U.S. coal production and of biomass needed to produce a nation’s energy 25 percent of US. coal reserves (3,27). Processed would be substantially greater than that needed coal feedstocks fit readily into most petroleum to produce its commodity chemicals. Starch prob- feedstock schemes for the production of commod- ably could not be used for energy production ity chemicals and thus do not require large capital without putting a strain on food and feed uses. investments for new chemical plants. Neverthe- Thus, if biomass is to be used extensively for less, at least one analyst thinks that petroleum will energy production, the biomass source will most continue to be used as a feedstock for commodi- likely be lignocellulose. ty chemicals for some time and that coal will not make a significant impact on the production of Biomass as an alternative to petroleum for U.S. chemicals until the 21st century (22). energy production was described in OTA’S July 1980 report Energy From Biological Processes It appears that countries with substantial inex- (30). As emphasized in that report, substantial pensive supplies of petroleum, such as Mexico and societal change, i.e., more public support and a , are turning to the production of higher priority for research on biomass use in the commodity chemicals as a way of adding value U.S. Departments of and Energy pro- to their resources, Thus, countries with petro- grams, will be necessary if biomass is to become leum may begin to control the price of these a viable alternative to petroleum as a source of chemicals. Because such countries may be able energy in the near future. At present, the level to produce commodity chemicals at a lower price, of U.S. public support for biomass research is not

● ● Biomass is all organic matter that grows by the photosynthetic high. Furthermore, Federal support of applied re- cent’ersion of solar energy. search and development (R&D) programs for al- Ch. 9—Commodity Chemicals and Energy Production 239 ternative fuel sources has been plummeting in the technology might improve the efficiency of bio- recent climate of intense fiscal scrutiny. mass conversion, thus facilitating the transition to the use of biomass resources. The advances A shift from petrochemical processes to bio- biotechnology could provide for the improved processes for the production of commodity chem- growth of plants used for biomass conversion are icals will be difficult because of the existing in- discussed in Chapter 6: Agriculture. frastructure of chemical and energy production. This infrastructure allows a barrel of to be con- Since commodity chemicals represent only a verted to products in a highly integrated system small portion of today’s U.S. petroleum consump- in which the byproduct of one reaction may form tion, a transition to biomass-based commodity the substrate for another reaction. Most chemi- chemical production without a concurrent tran- cals derived from biomass cannot yet compete sition to biomass-based energy production will not economically. with chemicals made from oil in this substantially reduce the country’s dependence on infrastructure. petrochemical resources. For moving the United States toward the goal of reduced reliance on im- AS the costs of bioprocesses are reduced ported, nonrenewable resources, a unified ap- through R&D, however, a transition to biomass proach to chemical and fuel production will be resources may become a more realistic proposi- necessary. tion. This chapter examines ways in which bio-

Biomass resources

The United States has abundant biomass re- This chapter emphasizes the use of the two sources. The largest potential amount of cellulosic most abundant feedstocks from biomass: starch biomass is from cropland residues such as corn and cellulose. Starch and cellulose are both poly- stover and cereal straw, * although the potential mers of glucose units [6- simple sugars) amount of cellulosic biomass from forest re- which, when hydrolyzed, yield glucose molecules sources is also quite large. About 550 million dry (see fig. 24). These glucose sugars provide the tons of hgnocelhdose are easily collected and avail- starting point for biological chemical production, able for conversion to chemicals each year. In for example, the transformation of glucose to eth- addition, some percentage of the 190 million dry anol. Other derivatives of biomass, such as vege- tons of corn produced yearly could be converted table oils, are used in bioprocesses, and those to starch and used for chemical production (21). resources are considered in Chapter 7: Specialty Chemicals and Food Additives. Parameters used to determine the optimal kind of biomass used in microbial systems include One drawback to the use of biomass as a feed- availability of the biomass, its energy content per stock for commodity chemical and energy pro- dry weight, the amount of energy that must be duction is its relatively low energy content per expended to achieve the desired products, the unit dry weight. Dry cellulose biomass, for exam- environmental impact of the process, and the ple, yields roughly 16 million Btu per ton and amenability of the material to conversion by ex- cornstarch yields 15 million Btu per ton, whereas isting microbial systems. Ultimately, biomass re- petroleum yields 40 to 50 million Btu per ton. sources that minimize usurpation of food sources Thus, the energy yield per unit of weight is lower are sought (e.g., nonfeed crops grown on extant for biomass than for petroleum. Furthermore, the arable land). costs of transporting biomass to a factory may bean important economic consideration. Raw ma- terial and transportation costs are particularly im- “Agricultural residues left On the soil aid in the sustainahilit~ of portant in the production of commodity chemi- soil. ‘I-he emrironmental impact of the remo~’al of these residues must be studied more thoroughly in order to determine whether agri- cals, because of the low value added to the feed- cultural wastes are, in fart, true wastes, stock in the synthesis of final products. .—— ——.

240 ● Commercial Biotechnology: An International Analysis

Figure 24.—Polysaccharides of Biomass: Figure 25.– Trends in World Grains Production Starch and Cellulose (million metric tons)

67/68 69/70 71/72 73174 75/76 77178 79/80 81182 Years

SOURCE: Off Ice of Technology Assessment, adapted from CPC, Int., 1983.

and this trend is expected to continue through the end of the century as the result of yield im- provement and an expansion of acreage planted (19). Furthermore, the price of corn has remained relatively constant over the past decade, especially when compared to the nearly tenfold increase in the price of oil over the same period of time. The utilization of U.S. corn has changed over the past 10 years. A decrease in U.S. meat con- sumption caused a concurrent decrease in the amount of corn used for animal feed, while at the same time, technological advances increased corn yields. Consequently, the export market for U.S. corn has risen from 15 percent of the crop to 35 percent. Since U.S. corn production is expected to increase and meat consumption is expected to decrease, U.S. farmers will need new markets for SOURCE Office of Technology Assessment. their corn. Commodity chemical production from a starch feedstock could provide a market for U.S. Starch corn. The potential for industrial use of starch from corn alone is large, and an increase in the Starch, a molecule composed of many hundreds industrial use of corn would probably aid in sup- of glucose units bound together in branched or porting farm prices. Currently, only about 7 per- unbranched chains, is the principal carbohydrate cent of the corn produced in the United States storage product of higher plants and is readily is processed into cornstarch (7,19). Figure 26 sug- available from such crops as corn and potatoes. gests that 14 percent of the 1990 corn crop could In 1979, the United States produced about 666 go to chemical production, and enough corn billion lb of grain from six major cereal crops, and would still be available for other uses. this grain contained 470 billion lb of starch. The Because of its high volubility in and ease major grain produced, corn, contained 316 billion of hydrolysis into individual glucose units, starch lb of starch (10), which could provide 285 billion is highly amenable to bioprocessing and may be lb of glucose. an ideal feedstock for chemical production. The As shown in figure 25, world grain production use of starch for both chemical and fuel produc- has increased steadily over the past several years, tion, however, might be at the expense of its use Ch. 9—Commodity Chemicals and Energy Production ● 241

Figure 26.— Trends in U.S. Corn Utilization in food production. Starch may not be produced in large enough quantities to be used both as a source of food and a source of energy. *

Lignocellulose

Lignocellulose is composed of cellulose, an un- branched chain of glucose units, lignin, a linked of aromatic molecules, and hemicellulose, a composed mainly of 5-carbon sugars. This structure provides the rigidity necessary for cellulose’s primary function, the support of plants. Because of its wide availability, lignocellulose has the potential to be the most important of all the raw materials for use in bioprocessing. Current- ly, however, several problems impede the use of lignocellulose on a large scale. Lignocellulose is highly insoluble in water and its rigid structure makes cellulose much more difficult than starch to hydrolyze to individual sugars. Furthermore, most microaganisms cannot utilize lignocellulose 1980/81 7230 million bushels directly without its having been pretreated either chemically or physically. Despite the considerable , advances made in both chemical and enzymatic seed, hydrolysis techniques, the cost of glucose derived from cellulose is still much higher than that de- rived from starch. The inherently diffuse nature of lignocellulose resources means that very high collection costs, especially in energy and manpower, will be en- countered in any attempt at large-scale utilization, These considerations have given rise to the con- cept that the utilization of lignocellulose for energy will be feasible only through a widespread network of smaller manufacturing facilities that draw on local resources and supply local needs. Indeed, this pattern has already been established for farm-scale alcohol production from corn. An alternative to multiple small-scale production units

*As detailed in OTA’S July 1980 report Energv From Bio]ogica/ Processes (30), starch could be used to produce approximately 1 1990 billion to 2 billion gal of ethanol in the United States each year (about 9760 million bushels 1 to 2 percent d U.S. gasoline consumption) before food prices might begin to rise. 242 Commercial Biotechnology: An International Analysis

is the concept of centralized, intensive lignocel- prospects for success, but the development with lulose production on so+-died “energy planta- biotechnology of more effective biological agents tions.” The potential ecological problems and high- for lignocellulose utilization could radically ly questionable economics have detracted from change this picture.

Conversion of biomass to commodity chemicals —

As noted above, there are numerous types of Figure 27.—Convers!on of Biomass to Commodity biomass resources, including lignocellulosic prod- Chemicals ucts and feed crops such as corn. Because of the varying compositions of these raw materials, dif- A. Starch biomass ferent methods are used in rendering them into Corn useful chemicals. Nevertheless, all microbial con- Oil version of biomass to marketable chemicals is a 1 * muhistep process that includes: Germ ● pretreatment (particularly with lignocellu- Gluten losic biomass), ● hydrolysis (saccharification) to produce hex- Starch I ose (6-carbon) and pentose (5-carbon) sugars, * ● bioprocessing of these sugars by specific * * micro-organisms to give commodity chemi- Dextrose Syrups Starch products cals, ● subsequent bioprocessing or chemical reac- tions to produce secondary commodity chem- B. Lignocellulosic biomass icals, and ● separation and purification of end products. Lignocellulose * Figure 27 is a schematic summary of the multistep 1 processes for the conversion of starch and ligno- cellulosic biomass to commodity chemicals. Al- though figure 27 emphasizes the microbial steps that could be used for these processes and appli- t # # Cellulose Hemicellulose Lignin cations of biotechnology to them, it should be noted that a variety of chemical syntheses can also *I *1 be used to convert the components of biomass into useful chemicals (9,10,17,18).

Pretreatment * = Possible microbiological step

Before either starch or lignocellulosic biomass SOURCE: Office of Technology Assessment can be used as feedstocks for bioprocesses, they must be pretreated in preparation for hydrolysis. Starch from corn requires little pretreatment. Lig- STARCH nocellulosic materials such as wood, however, de- The United States relies primarily on corn for mand extensive pretreatment to make cellulose starch feedstocks. About 500 million bushels are and hemicellulose available for hydrolysis. processed by corn refiners yearly to produce Ch. 9—Commodity Chemicals and Energy Production ● 243 cornstarch products. In the production of corn- fied, but efforts to use micro-organisms for de- starch, refiners employ a process known as “corn lignification are hampered by the fact that lignin wet milling” in which corn kernels are cleaned, metabolizes are toxic to these micro-organisms. soaked in warm, dilute acid, and ground to yield Thus, more work remains to be done before bio- a slurry composed of starch, protein, and oil. delignification and other methods of biological Much of the starch is further converted to sweet- pretreatment are competitive with the current- eners, such as glucose and high fructose corn ly used chemical or mechanical pretreatment syrup (7). Cornstarch is the milling product that methods. Were more information available on could be used to make commodity chemicals. these micro-organisms, biotechnology could be used to improve their efficiency. The pretreatment of starch requires minimum inputs of acid and heat. Energy requirements are Hydrolysis low compared with the potential energy gained, and almost all byproducts are marketable. Com- STARCH bined with starch thinning and saccharification costs (see below), corn wet milling is estimated Enzymes from microbial systems are widely to yield monomeric sugar at a cost of 12¢lb (at used industrially to catalyze hydrolysis of starch $3.40/bushel of corn) (21). into sugars. * Batch bioprocesses are used for hydrolysis. Three enzymes, alpha -amylase, beta- LIGNOCELLULOSE amylase, and glucoamylase, are used to hydrolyze the starch chains to yield complete hydrolysis and Methods used to pretreat lignocellulosic bio- the formation of glucose (15). The largest indus- mass include chemical pretreatment in acids and trial use of enzymes is in the corn wet milling bases, steam explosion, and mechanical grinding. industry. These methods, described in OTA’S July 1980 bio- mass report (30), add substantially to the costs in- The major U.S. corn refiners have ongoing ac- volved in using lignocellulosic biomass as a chem- tive research programs for the improvement of ical resource. enzymatic degradative processes, and these man- ufacturers have made major advances in the areas In the future, biodelignification (the biological of bioprocessing and enzyme immobilization. degradation of lignin) by micro-organisms may These manufacturers have continued their efforts prove useful in the pretreatment of lignocellulosic toward improvement of enzymes by using new biomass (8,24). Biodelignification results in remov- biotechnology (32). al of lignin, exposing the crystalline cellulose and lowering the costs of mechanical pretreatment. CELLULOSE At present, however, biodelignification is an in- adequate, expensive means of pretreatment, and The well-ordered crystalline structure of cel- it is not used in the pilot projects for use of ligno- lulose necessitates harsher treatments than those cellulose currently underway. As yet, there are used for starch. Whereas hemicellulose is readi- no valuable uses for lignin. Uses must be found ly hydrolyzed into its 5-carbon sugars under mild for lignin derivatives before these processes will conditions, the hydrolysis of cellulose requires be commercially viable (2). strong acids, heat, and pressure. These conditions lead to the formation of byproducts which must Several groups are working toward obtaining be separated and utilized to minimize the overall faster biodelignification using mixed cultures of costs of lignocellulose use. In addition, the acid micro-organisms, but microbial reaction rates at used for the hydrolysis of cellulose must be neu- present do not approach those needed for eco- tralized before the mixture is used for bioprocess - nomic feasibility. With use of the best candidate, ing, a requirement that raises the cost of hydrol- the degradative mold Chysosporium pruinosum, ysis. 40 percent of lignin remains intact after 30 days of treatment (l). At least 20 strains of bacteria that ‘For further discussion of these enzymes, see Chapter 7: Specialtbv have Iignodegradative abilities have been identi- Chemicals and Food Additi\’es. 244 Commercial Biotechnology: An International Analysis

The use of enzymes known as cellulases (and Another possibility for a biotechnological im- microorganisms that produce cellulases) to hy- provement is to transfer the ability to utilize the drolyze cellulose, either alone or in conjunction 5-carbon sugars from hemicellulose into cellulose- with chemical treatment, offers an increasingly utilizing microorganisms. A third possibility is im- popular alternative to chemical methods of hy- proving the specificity of organisms that can uti- drolysis. Cellulose is the most abundant biological lize lignocellulose directly, e.g., Clostridium ther- compound on earth, and a myriad of micro- mocellum. The “wild types” of these micro- organisms employ cellulases to obtain energy for organisms produce a range of products, typical- growth from the resulting glucose molecules. Re- ly ethanol and several organic acids. This varied search efforts to improve cellulase activity by synthesis results in low yields for each product mutagenesis and selection of cellulolytic (cellulose- and great difficulties in subsequent recovery and degrading) microa-ganisms have yielded mutant purification. Genetic mechanisms could be used strains of microa-ganisms (particularly fungi) that to select for high production of any one of the produce cellulases with higher tolerance to glu- products. cose (the product of hydrolysis that inhibits cel- lulase activity), increased efficiency and reaction Microbial production of commodity rate, and better functioning at the elevated tem- chemicals peratures and high acidities used in industrial bio- processes (l). Some commodity chemicals, including ethanol and acetic acid, are now produced in the United The enzymatic activity of cellulases has been States with microbial bioprocesses (9), while other improving over the past several years, and in chemicals, such as ethylene and propylene, will some cases, the time needed for saccharification probably continue to be made from petroleum and subsequent bioprocessing to produce ethanol feedstocks because of lower production costs. The from cellulose has been reduced several fold (11). commodity chemicals that are attractive targets Despite these improvements, however, the activi- for production from biomass include ethanol, ace- ty of cellulases does not begin to compare with tone, isopropanol, acetic acid, , pro- the activities of amylases, which are about 1,000 panoic acid, fumaric acid, , 2,3-butanediol, times more catalytically efficient (5). methyl ethyl ketone, glycerin, tetrahydrofuran, and adipic acid (9,18). Additionally, some chemi- Although research into the molecular biology cals, such as lactic and levulinic acids, could be of cellulases is in its early stages, biotechnology used as intermediates in the synthesis of polymers is being used to improve the cellulase-catalyzed that might replace petrochemically derived poly- hydrolysis of cellulosic biomass in several ways. mers (18). Two challenges for biotechnological approaches to cellulase production are increasing the low ac- Because the chemical composition of biomass tivity of the cellulase and making sure the entire differs from that of petroleum and because micro- cellulase gene complex is expressed. Processes organisms are capable of a wide range of activi- that optimize cellulase activity and efficiency are ties, it maybe that the most important commodity prerequisite to the use of lignocellulosic biomass chemicals produced from biomass till be, not resources. chemicals that directly substitute for petrochem- icals, but other chemicals that together define a Researchers at the National Research Council new structure for the chemical industry. Micro- of Ottawa, Canada, the University of British Co- organisms used to produce organic chemicals lumbia, the University of North Carolina, and Cor- could be used with micro-organisms that fix ni- nell are using recombinant DNA (rDNA) tech- trogen to produce nitrogenous chemicals, either niques to clone cellulase genes from several higher value-added compounds or , a micro-organisms into bacteria that may be in- high volume commodity chemical. Other micro- duced to produce cellulase in large quantities (20). organisms, such as the methanogens or the micro- Similarly, researchers at the U.S. Department of organisms that metabolize sulfide, may Agriculture are cloning celhdase genes from the be used to produce sulfur-containing chemicals fungus Penicillium funiculosum (12). (14). Ch. 9—Commodity Chemicals and Energy Production ● 245

The aerobic and anaerobic microbial pathways responsible for these reactions are listed in table leading to a number of important compounds are 40. Knowledge of biochemical pathways for the shown in figure 28. Some of the micro-organisms synthesis of particular chemicals will lead to the

Figure 28.—Metabolic Pathways for Formation of Various Chemicals

? 6X)*

SOURCE T K Ng, R M Busche. C C. McDonald, et al “ProductIon of Feedstock Chemicals.” Science 219:733.740, 1983 246 “ Commercial Biotechnology: An International Analysis

Table 40.—Potentially Important Bioprocessing Systems for the Production of Commodity Chemicals

Micro-organism Carbon source(s) Major fermentation product(s) Saccharomyces cerevisiae...... Glucose Ethanol Saccharomyces cerevisiae...... Glucose GI ycerol Zymomonas mobilis ...... Glucose Ethanol C/ostridium thermocellum ...... Glucose, Ethanol, acetic acid C/ostridium thermosaccharo/yticum...... Lactic acid Glucose, xylose, ethanol, acetic acid C/ostridium thermohydrosu/furicum...... Glucose, xylose Ethanol, acetic acid, lactic acid Schizosaccharomyces pombe ...... Xylulose Ethanol K/uyveromyces Iactis ...... Xylulose Ethanol Pachysolen tannophilus ...... Glucose, xylose Ethanol Thermobacteroides saccharolyticum ...... Xylose, glucose Ethanol Thermoanaerobacter ethano/icus ...... Glucose, xylose Ethanol, acetic acid, lactic acid C/ostridium acetobuty/icum...... Glucose, xylose, arabinose Acetone, butanol C/ostridium aurianticum ...... Glucose Isopropanol C/ostridium thermoaceticum ...... Glucose, fructose, xylose Acetic acid Clostridium propionicum ...... Alanine Propionic acid, acetic acid, Aeromonas hydrophilic. , ...... Xylose Ethanol, 2,3-butanediol Dunaliella sp...... Carbon dioxide Glycerol Aspergil/us niger ...... Glucose Citric acid Aerobacter aerogenes ...... Glucose 2,3-butanediol Bacillus polymyxa ...... Glucose 2,3-butanediol

SOURCE Office of Technology Assessment, from T. K. Ng, R. M. Busche, C. C. McDonaldt et al., “Production of Feedstock Chemicals,” Science 219:733.740, 1963; J C. Linden and A Moreira, “Anaerobic Production of Chemicals,” Bask Biology of New Deve/o~rnerrts In Blotec/mo/o~y (New York: Plenum Press, 1963); and D I C Wang, Massachusetts Institute of Technology, personal communication, 19S2.

identification of the genes that control the syn- cy of sugar utilization; faster rates of production; thesis of these chemicals. With such knowledge, tolerance to higher temperatures, so that separa- it will be possible in some instances to employ tion and purification methods (which often re- rDNA technology or cell fusion methodology to quire elevated temperatures) can be coupled with yield microorganisms with improved bioconver- bioprocesses; * * selected drug tolerance, so that sion efficiencies. Improvements of these micro- growth of contaminant bacteria can be inhibited organisms by genetic manipulation at present are by drug treatment; and better growth on a variety limited to a few cases. Examples include the de- of biomass sources (26). Another major need is velopment of a pseudomonas putida plasmid that the identification of plasmids that can be used as codes for proteins that hydroxylate chemicals and vectors for the transmission of useful genetic the development of rDNA plasmids in E3cherichia information. coli that provide the genes that code for enzymes that convert fumarate to succinate (21). In developing commercial bioprocesses, a ma- jor need is for micro-organisms with character- istics such as tolerance to increased levels of prod- ucts during bioprocess reactions;* better efficien-

“The most commonly used micro+xganism for ethanol fermen- tation is yeast, which tolerates ethanol concentrations up to about ● ● A combination of bioprocmsing and purification could be imple- 12 percent. Since the purification of ethanol from such dilute solu - mented whereby products are continuously removed and coUected. tions is costly, a desirable goal is to develop organisms (and thus In this case, the high temperatures would minimize contamination emem=) whose to]era~e to end products is higher. Such organisms by other organisms and avoid product concentrations high enough could be used as hosts for cloned bioconversion genes. to kill the micm-organisms (13,37). Ch. 9—Commodity Chemicals and Energy Production ● 247

International research activities

Biomass-related research in the United States Differing emphasis is placed on the biological is conducted by the Department of Energy (DOE), production of chemicals and fuels by the govern- the National Science Foundation, and private com- ments of foreign countries. The panies. Programs within DOE include the Biomass funds biotechnological applications to chemical - program, which examines the production processes through several govern- technical feasibility of innovative biomass feed- mental departments. The Canadian Development stock production and conversion technology; the Corporation is pursuing technology develop- Alcohol Fuels program; and the Biological Ener- ment for producing ethanol from aspen wood gy Research program (within DOE’s Office of Ba- ($21 million over 5 years), and several other sic Energy Science), which funds research on ge- Canadian Government agencies are addressing netic manipulation of plants for increased biomass chemical and energy production from biomass. production and of micro-oganisms for improved Japan, France, and Sweden also have Govern- bioprocessing. DOE’s Energy Conversion and ment-funded programs pursuing the use of bio- Utilization Technologies (ECUT) group recently mass as a feedstock for chemicals and energy (33). started a program in biocatalysis specifically in Profiles of recent U.S. patent activity indicate response to the potential use of rDNA organisms widespread attention by private inventors and in chemical production processes. The goal of this companies in the United States and other coun- generic applied research program is to build “bio- tries to biomass conversion, particularly in areas technology to enable industry to displace related to hydrolysis of starch to sugar, the pro- a significant level of nonrenewable resource re- duction of higher value-added chemicals such quirements by [the year] 2000” (33). The ECUT as amino acids from microbial systems, and im- program focuses on research on scale-up of bio- provements in bioprocess systems such as en- processes, monitoring continuous bioprocesses, zyme immobilization (32). Organizations with the bioreactor design, and downstream product sep- most U.S. patents in starch hydrolysis and related aration. bioprocesses include CPC International Inc. (U.S.), The Reagan administration’s proposed fiscal with 21; A. E. Staley Manufacturing Co. (LJ.S.), year 1984 budget is not generous to biomass con- with 18; A. J. Reynolds Tobacco Co. (U.S.), with version for energy programs. The budget re- 8; France’s National Agency for the Funding of quests $17.3 million to support ‘(fundamental Research (L’ Agence Nationale de lralorisation de R&D” in this area, a small increase of $1.3 million la Recherche); Anheuser-Busch, Inc. (U.S.), and Ha- (8.1 percent) from fiscal year 1983. Alcohol fuels yashibara Biochemical Laboratories, Inc. (Japan), R&D, formerly budgeted separately, would be with 7 each; and Novo Industri A/S (Denmark) and combined with biomass energy programs (25), Miles Laboratories Inc. (U.S.), with 5 each (32). Since some of this R&D relates to studies of mi- Even though patents in starch hydrolysis do not crobial chemical production, any change in Fed- give a conclusive view of future biotechnological eral support for R&D of biomass energy will ef- applications to the commodity chemical industry, fectively alter R&D for biological commodity they do indicate that U.S. companies are the pre- chemical production. The only DOE program spe- dominant developers of the bioprocess technology cifically directed toward the use of new biotech- underlying the utilization of starch biomass. nology, the ECUT program, received no funding for fiscal year 1984. _

248 ● Commercial Biotechnology: An International Analysis

Conclusion

The production of low-value-added, high-vol- products may foster other bioprocess develop- ume commodity chemicals demands the use of ment. In order for this transition to take place, the most economic production schemes available. however, either the costs of producing these The most economic schemes for chemical and products must be reduced (about 20 to 40 per- energy production at present favor the use of cent of their existing costs) or the price of petrochemical feedstocks. In the future, however, petroleum must rise. Reducing the costs of pro- decreasing petroleum supplies, increasing oil duction of chemicals from biomass is a prerequi- prices, and technological advances in biomass site to commercial success in all case studies thus utilization may foster a transition to the use of far. feedstocks derived from biomass. Such a transi- U.S. Government support for applications of tion is not expected to occur on an industrywide biotechnology to the conversion of biomass is de- scale in the near future, but bioprocesses are creasing, while high levels of government support being used to produce significant amounts of fuel- are provided in several competitor countries, par- grade ethanol from corn and other crops econom- ticularly Japan and the United Kingdom. U.S. com- ically. panies appear to be active in developing certain Because of the potential for disruption of the biotechnological applications, but most of this ac- existing industrial structure, the complex inter- tivity as reflected in patents is concentrated in relationships that characterize the production of applications to starch conversion, with primary commodity chemicals will affect the success of emphasis on higher value chemicals which are the introduction of particular compounds pro- expected to be produced before biomass-based duced by microbial bioprocesses. Projected bio- commodity chemicals are made. Some companies processing costs of commodity chemicals and the in the united States and other countries are ac- structure of the chemical industry have been in- tive in bioprocess development, but given the cur- vestigated by B. O. Palsson, et al, (23). These in- rent slow pace of R&D in microbial systems that vestigators concluded that the potential exists for perform the chemical conversions, these proc- a smooth introduction of four microbial products esses will not be applicable in the chemical in- (ethanol, isopropanol, n-butanol, and 2,3-butanoO dustry for some years. into the U.S. chemical industry, and that these

Priorities for future research *

Biotechnology will be a key factor in develop- production of commodity chemicals because ing economic processes for the conversion of bio- incremental improvements in bioprocess mass to commodity chemicals. A number of pri- technology will be readily reflected in the orities for research that will improve the efficien- price of these chemicals. cy of the conversion of biomass to useful chemi- ● screening programs to identify micro-orga- cals can be identified: nisms (and their biochemical pathways) use- ful to processes such as commodity chemical ● bioprocess improvements, including the use synthesis, cellulose hydrolysis, lignin degrada- of immobilized cell and enzyme systems and tion, and catalysis of reactions that utilize by- improved separation and recovery meth- products that are currently unmarketable; ods, * * an area especially important to the ● developing host/vector systems that facilitate “k!anj of these suggestions are from Rabson and Rogers (24), increased production of commodity chemi- ● ‘See Chapter 3: 7he Technologim for a more extensi~’e discus- cals by gene amplification and increased gene sion. expression of desired products and that allow Ch. 9—Commodity Chemicals and Energy Production ● 249 ——

the transfer of genes into industrially impor- ● understanding the genetics and biosynthetic tant micro-organisms; pathways for the production of commodity ● understanding the structure and function of chemicals, especially for the strict anaerobic the cellulase and ligninolytic activities of bacteria such as the methanogens and the micro-organisms; clostridia; ● understanding the mechanism of survival of ● understanding microbial interactions in micro-organisms in extreme environments, mixed cultures; and such as high temperature, high pressure, ● developing an efficient pretreatment system acid, or salt; for lignocellulose. ● understanding the mechanism of cell toler- ance to alcohols, organic acids, and other or- ganic chemicals;

Chapter 9 references*

*1.

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3. 13. 4.

.5. 14. *b,.

1.5. 4.

8, 16.

17. :)

* 18. 10

19.

11 ~().

*21. 250 . Commercial Biotechnology: An lnternational Analysis

25< 33

26, 34

35.

27, 36

28. 37

29