Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Chapter 8 Cellulose Conversion Cellulose is the earth's most abundant renewable raw material, with about 10-15 t per person produced annually by plants. Most of this cellulose occurs in intimate association with a complex plant structural material called lignin. The resulting lignocelluloses are by far the most prevalent renewable organic materials available for microbialor otherconversions. Cellulose that is not lignif~ed (for instance, nonwoody aquatic plant tissues, some papers, residues from chemical pulp mills, and certain natural fibers such as cotton) may be available in sufficient quantity in some locales to be considered for microbial conversions. A wide range of microorganisms can degrade cellulose. Far fewer species can degrade the natural lignocellu- loses because lignin limits access to the cellulose. In fact, at present, the only currently operative means for converting unmodified lignocellulosics bio- logically is through the production of various mushrooms, which are a good source of protein for human consumption. Pretreatment to disrupt or destroy the lignin barrier permits use of a broader range of microorganisms. Both physical and chemical pretreatments have been developed, but the former requires large amounts of energy. Chem- ical pretreatment might be attractive in some situations, however, and two that are now under investigation seem promising. In one, lignocellulose com- plex is treated with concentrated phosphoric acid, in the other the lignocellu- lose residues are treated with sulfur dioxide gas. In both cases this is followed by neutralization with a base. For some organisms it is necessary to disrupt the lignocellulose complex and remove the lignin; for others removal of lignin is not necessary. Pretreat- ment using easily manipulated reagents and unsophisticated equipment is necessary for a cottage industry. Ambient temperature processing with min- eral acids or alkalis followed by neutralization would meet these require- ments but adds to the cost. Certain fungi, such as the mushrooms, decompose lignin and some can be used effectively for pretreating lignocelluloses. Table 8.1 lists nine microorganisms or processes that are either promising or already in commercial use for the conversion of cellulose or lignocellulose. As shown in Table 8.2, five of these require cellulose or pretreated lignocellu- lose for efficient conversion. The processes vary not only in the type of substrate and the product, but also in the degree of sophistication and in the 142
CELLULOSE CONVERSION 143 present state of knowledge and development. For each process, Table 8.2 lists a specific organisms along with some of the conditions related to its use. In the following pages, each process is discussed in more detail. Volvariel/a Species "Padi-straw" mushrooms (V. volvacea, shown in Figures 8.1 and 8.2, and V. esculenta and F. displasza) are cultivated on rice straw and similar mate- rials in the Orient and Africa. They are of increasing commercial importance, but are also traditionally cultivated by individuals. They show promise of greatly expanded use in grain-growing regions of the tropical world. Produc- tion involves simply inoculating water-soaked straw in flat beds, maintaining moisture at optimum levels, and harvesting the several crops of mushrooms. The mushrooms may be dried for storage and later use. The spent straw is used to inoculate fresh beds and is probably also used as animal feed. Before 1970, rice straws were practically the only material used for the preparation of the medium for the mushroom. Recently, a number of other materials such as water hyacinth, oil-palm nut pericarp, cotton, and ba- nana leaves have been shown to be satisfactory culture material. Undoubtedly many other lignocellulosic agricultural residues could also be used satis- factorily. Kolvariella is primarily a fungus of the tropics and subtropics, the areas that include most of the developing countries. These are also the areas in which land is often considered to be the limiting factor in the production of food. In the case of mushrooms cultivated on agricultural residues, land ceases to be an important factor. According to recent data, 1 m2 of growth space can produce 586 kg of mushrooms per year based on two crops per month. Limitations There are no important limitations to the cultivation of Volvariella species within the environmental range of growth. Research Neecis To support increased growth of Volvariella species for food, the following research efforts are needed: · Determination of the best species and strains for given locations and substrates; · Determination of the optimum environment for each species; and · Evaluation of various substrates for maximum yields of the mushrooms. .
144 MICROBIAL PROCESSES TABLE 8.1 Products of Cellulose- or Lignocellulose-Utilizing Microorganisms Microorganism Product Present Status Volvariella volvacea Human food (mushrooms); Some commercial animal feed use Lentinus edodes Human food (mushrooms); Used commercially Pleurotus sp. Thermoactinomycetes sp. and other thermophilic actinomycetes Ph. an erochae te chrysosponum Trichoderma Reese Clostridium thermocellum Pseudomonas fluorescent var. cellulosoe and similar bacteria Thermophilic Sporocytophaga animal feed Human food (mushrooms); animal feed Human food (SCP); Under research animal feed Used commercially Delignified cellulose Under research for use as feed, fiber, or further conversions Cellulases for converting cellulose to sugars; animal feed (SCP) Cellulases for converting cellulose to sugar; ethanol, acetate, lactate, and H2; animal feed (SCP) Under development Under research Animal feed; cellulases Under research for converting cellulose to sugars Animal feed; ethanol, acetic Under research acid Lentinus edodes The "shiitake" mushroom has been cultivated and used as human food for centuries in China and Japan, where it is commercially produced in what now is a multimillion dollar industry. It is not used much in most developing countries, nor is it popular in the West where the common champignon, Agaricus bisporus (A. brunnescens), is the mushroom of commerce. L. edodes (Figure 8.3) has an important advantage over A. bisporus in that it can be cultivated on wood, mainly but not exclusively on oak (Figure 8.4~. Thus, it has potential for the direct bioconversion of lignif~ed residues and low-quality wood into fungal protein. Wood decayed by L. edodes is quite digestible by ruminants, although this potential use of the organism has received little attention. In general it takes 1~-3 years for the production of the fruit bodies after inoculation in log wood. A new method, involving direct injection of the liquid spawn into log wood, has shortened the fruiting time to about 6 months. With this method, the number of spawning points can be increased.
· - £ ~ Ct C) EM Cal Cal o ~4 Cal o. o Cal o - c) o ._, ._ ._ ._ Cal £ ._ Cal on o o C) ._ JO US C) · _ en Cal C: Cal Cal o Go o ~ _ ~ o o c: 5 I Ct V: CQ ._ ._ _ ._ V) ~ £ Cal ._ Cal ~4 o o Cal ._ Cal Cal ~ Cal Cal Via Cal ~ Cal UP Cal o ~ ~ ~ ~ ~ ~ Ct ~ ~ 3 ~ ~ ~ ~ ~ ~ 1 ~ lo, ._ .~= Is ~ ~ ~ V I: I, ~ ~ ~ o ~ I ~ ~ o ~s, ~ ~ =, O * * * ~ 0 0 0 C) Z Z Z ~ C~ ~ C~7 U~ V~ a~ c C) ~ '_ Q;~ C-- C) ~ ~ = ^ :5 3 0 ,~ a O ~ a ° ^ 0- :~ a ~ a ~ O ,, a c' 3 ~ 0 ~ 3 ~ ~ O a, ~ O ~ O ~ ~ O ~ O O :, ~ O ~ ~ ~ O ~ ~ O ~V ~ O t1) ~ ~ O O C.) ~ O ~ ~ O ~ S: ~ ~ ~ ~ ~ ~ 3 ~ _ _ ~ ~ ~ 3 ~ == 3 ~ ~ ~ .= .= .~4 ~ C;, to 4 ~ ~ ~ V V ~ V V V `. . , C~ ~ C~ o o o C) o o C~ ~ o z Z Z ~ z Z ~ ~ z =. ~ ~; o o; C , S =- ° ° O ' ~ · 145 o ._ ~. c~ o o~ - ._ c, c~ o 4) s s~ ce c~ u, c, u' ._ - o o c: *
146 ..~ ................................... ...... ..... ~3114 MICROBIAL PROCESSES FIGURE 8.1 Fruiting bodies of Volvariella volvacae on straw-cotton waste compost. (Photograph courtesy of S. T. Chang) FIGURE 8.2 The "button" (left) and "egg" stages of Volvariella volvacea. (Photograph courtesy of S. T. Chang)
CELLULOSE CONVERSION 147 FIGURE 8.3 Lentinus edodes fruiting one year after inoculation on bolts of oak wood in Japan. (Photograph courtesy of Y. Hashioka) FIGURE 8.4 Typical arrangements of bolts of oak wood for cultivation of Lentinus edodes (Japan). (Photograph courtesy of Y. Hashioka)
148 MICROBIAL PROCESSES It also reduces the amount of manual labor and minimizes the loss of wood. The shiitake mushroom is quite perishable, and the best way to preserve its volatile compounds, amino acids, vitamin B content, and texture is by freeze drying. Freeze-dned mushrooms are very close in composition to the original fresh samples. Most of these mushrooms, however, are simply air-dried for storage and marketing. Limitations L. edodes may not be suitable or efficient for use with many available woods. No other limitations are expected within its environmental range. Research bleeds Further study should be focused on: . Evaluation of available wood species; · Selection of best strains for specific substrates; and · Evaluation of L. edodes wood residue as a ruminant feed. Pleurotus Species The "oyster" mushrooms (Pleurotus ostreatus and P. sojor-caju) and other species (P. florida, P. eryngii, P. comucopiae, and P. cystidiosus; Figure 8.5), like L. edodes, preferentially decompose lignin, although they also utilize cel- lulose and other carbohydrate polymers in wood. As many as three successive FIGURE 8.5 Fruiting bodies of Pleurotus cys~diosus, a commercial and popular mushroom in Taiwan. (Photograph courtesy of J. T. Peng)
CELLULOSE CONVERSION 149 harvests on a single substrate batch have been reported. These species have the potential for converting sawmill residue and other low-value wood into protein-rich food for human consumption. All are currently used as food. P. cornucopian is grown commercially in Japan and P. ostreatus is grown com- mercially in Eastern and Western Europe, but they apparently axe little used in developing countries. P. ostreatus and P. Florida have temperature optima near 30°C, making them promising for tropical applications. All can be culti- vated on straw and on mixtures of sawdust, grain, manure, food-processing wastes, and similar substrates with an added nitrogen source such as com- mercial fertilizer. A large spawn inoculum eliminates the need for sterilization as the mycelia quickly take over. Yields vary; the highest reported is 100 percent (1 kg per kg of dry substrate) on banana pseudostems. Limitations Substrates usually need to be pasteurized unless a large inoculum is used. There are no other important limitations within a suitable environmental range. Research Needs The study of Pleurotus sp. should be concentrated on: · Further improvement of cultivation conditions; and · Selection of the best strains for each location and substrate. Thermoactinomyces Species The thermophilic cellulolytic and starch-utilizing actinomycetes provide a unique opportunity for development of a cottage industry for the production of single-cell protein for food or animal feed. They can be grown on high solids (40-60 percent moisture) under conditions of aeration and tempera- ture in which most contaminants cannot compete. At 40-60 percent moisture, the biomass is a thick paste or a damp, friable solid. It can be spread as a thin layer in trays or on fine mesh screens in an incubator. The screens are preferable to trays because both sides are exposed to air. It is necessary to control temperature, moisture content, pH, and oxygen content during growth. The organisms tolerate variations in tempera- ture (50°-65°C), moisture (40-60 percent), pH (6.8-8.5), and oxygen (1-20 percent). All plants and plant wastes are potential substrates for these organisms.
150 MICROBIAL PROCESSES Starchy materials such as cassava, banana, potato, and corn starch can be used directly, while cellulosic materials require pretreatment. The extent and kind of pretreatment depends upon the substrate. Waste newspaper usually con- tains lignocellulose and may require pretreatment. Soft woods contain more lignin and may require more extensive pretreatment than hardwoods. The lignin content of all fibrous plants increases with age. Therefore, young suc- culent plants may be utilized without pretreatment, while mature plants of the same species will require pretreatment. Removal of the lignin is not necessary for cellulose utilization and growth, but the lignocellulose complex must be ruptured, so cellulolytic enzymes can penetrate and hydrolyze the cellulose. Without pretreatment, cellulose utilization is much less complete. Using this organism on various starch and cellulose substrates would be labor intensive but would require minimal capital and technology. The pro- cess is no more complicated than making cheese or wine. It can be carried out under clean but nonsterile conditions. However, an environment should be selected in which undesirable contaminants cannot grow. Thermophilic actinomycetes such as Thermoactinomyces sp. have the fol- lowing characteristics, making them good candidates for a cottage industry: . They grow at 55°-65° C. Twenty-four hours or more of growth at this temperature range results in a pasteurized product in which most known pathogens would be destroyed. . They grow rapidly, with a minimum of growth requirements. Fermenta- tion should be complete within a few days. · If proper control of temperature and moisture is exercised, thermo- philic actinomycetes will be the predominant if not the only organism present. Only actinomycetes, thermophilic bacteria, and a few algae grow above 55°C. If the moisture content is kept in the range of 40-60 percent, other bacteria cannot compete effectively. Thermophilic algae will not be a problem in dark growth chambers. · Nutrients and seed culture can be added from a prepackaged mix, just as yeast is now prepared for bread and wine making. · A variety of inexpensive organic and inorganic nitrogen sources can be used. · Temperature and moisture can be manually controlled by moving trays to different incubators or to different parts of the same incubator. Limitations Thermoactinomyces sp. does not efficiently utilize lignin-cellulose com- plex found in most plants. A pretreatment of the substrate may be needed in some cases. "Farmer's lung" is a possible occurrence; it is caused by inhalation of large numbers of spores, and is an allergic response rather than an infection
CELLULOSE CONVERSION 151 caused by colonization of the respiratory tract. The symptoms are cate- gorized as hyperactivity pneumonitis or extrinsic allergic alveolitis. If condi- tions are maintained so that the product remains moist, spore inhalation can be minimized. Thermophilic actinomycetes have not been reported to pro- duce aflatoxins or other mycotoxins, as have many of the higher fungi. Research bleeds The following research efforts should be emphasized: · Composition analysis of the single-cell protein product; · Nutritional evaluation of the product; · A detailed description of the construction and operation of a low- technology incubator; · Preparation of a culture and nutrient packet; and · A description of methods for use and preservation of the product. Phanerochaete chrysosporium A ubiquitous wood-decay fungus that inhabits the northern hemisphere is called, variously, Peniophora "G." Ch7ysosponum pminosum, C. Iignorum, Sporotrichum pulverulentum, S. pruinosum, and P. chrysosporium. It is one of the organisms most damaging to stored wood chips, and, like Pleurotus sp. and L. edodes, decomposes all components of wood. Among the several hundred species of lignocellulose-destroying fungi, P. chrysosporium is unusual in that: 1) it produces copious quantities of asexual spores, malting it easy to handle; 2) it is thermotolerant, growing optimally at 35°-40°C, but also growing well at 25°C; 3) it grows very rapidly and is an aggressive com- petitor; and 4)it decomposes lignin as rapidly as any organism thus far studied. Therefore, P. chrysosporium has been selected for detailed study of lignin degradation and the microbial processing of wood. This fungus should be studied further for converting wood-processing residues and other signified wastes. The selective degradation of lignin caused by the fungus increases rumen digestibility, and the fungal mycelium adds protein. Partial decay of wood wastes by P. chrysosporium should render them suitable for ruminant feed or for further digestion to sugars by cellu- lolytic enzymes (see discussion of Trichoderma reesei below) or by bacteria. The fungus has been fed to fish and rats as the sole protein source with no adverse effects. Limitation Some substrates might have to be pasteurized for successful growth of the organism.
152 Research Needs MICROBIAL PROCESSES Further study on P. chrysosporium should have the following goals: · Determining optimum conditions for delignification of specific sub- strates: · Evaluating properties of products; · Selecting superior strains and achieving genetic improvement; and Establishing sterility requirements. . Trichoderma reesei A number of fungi are cellulolytic, but only a few produce cell-free en- zymes in sufficient quantity to be of value in degrading cellulose. Tri- choderma reesei forms a stable cellulase system that is capable of extensive degradation of cellulose. T. reesei grows rapidly on simple media and does not require supplemental growth factors. In agitated culture, it produces short mycelial threads; rarely does it form pellets on carbohydrates. It is a strong acid producer and will grow under pH conditions as low as 2.5; during actual enzyme production, the medium can be adjusted to pH 3, thus minimizing contamination. Media can be inoculated with a spore suspension or with a small volume of cellulose- containing mycelia. To obtain the highest yield of enzyme, interfering substances such as lignin must be removed and the cellulose pretreated. The cellulases of T. reesei have been studied more extensively than those from other organisms. There is extensive literature on conditions of grows for enzyme production, enzyme isolation and purification, and properties of isolated enzymes. If a commercial process for large-scale use of cellulase enzymes is developed, it will probably use T. reesei. Little research has been done on SCP production by T. reesei. The protein content and amino acid profile are similar to the microfung~ in that the protein is limited in sulfur-containing amino acids. The value of the protein from T. reesei in hum art nutrition has not been reported. Limitations The use of Trichoderma reesei will most likely be limited to the produc- tion of enzymes from pretreated cellulosic material. This will require fer- menters and fermenter technology that may not be available in some devel-
CELLULOSE CONVERSION 153 oping countries. Native lignocellulose would require pretreatment, such as deli~ification. If T. reesei is grown under nonsterile conditions there is a danger of contamination by mycotoxin-producing fungi. Research bleeds Many basic and pilot-plant studies have been completed. But more work will be needed, especially on: · Production of cellulase from Trzchoderw~a reesei by the koji process; and · Methods for increasing enzyme production, substrate-enzyme suscepti- bility, and enzyme recovery after use. Other Species* Some gram-negative, aerobic bacteria such as those in the genera Pseudo- monas and Xanthomonas as well as gram-positive Cellulomonas species utilize cellulose but do not utilize lignin; therefore, some form of pretreatment before fermentation is required. These bacteria grow rapidly at room temper- ature (20°-30°C), are obligate aerobes, and usually require yeast extract or some growth factors. These nonspore-forming bacteria are readily digested by livestock. The amino acid composition is similar to that of other bacteria and constitutes a source of nutritional protein. Co-fermentation of mesquite wood with P. fluorescences and a yeast, Can- dida utilis, has been conducted. The protein yield of Cellulomonas has been increased by co-fermentation of cellulose with Alcaligenes faecalis and with Cellulomonas flavigena and Xanthomonas campestris. Apparently, co-fermen- tation with a noncellulolytic organism increases the rate of utilization of soluble sugars produced by hydrolysis of cellulose. Limitations The bacteria mentioned above grow at pH levels of 6.5-8.0 and the fer- mentations are subject to contamination by noncellulolytic bacteria as well as pathogens; therefore, aseptic conditions must be maintained throughout the fermentation. The need for pretreatment, either chemical or biological, in- *See also discussion of SCP production in Chapter 2.
154 MICROBIAL PROCESSES creases the cost of protein produced. These bacteria are small (about 1,u x 0.5,u) and must be harvested by differential centrifugation or recovered on very fine filters. Research Needs Research is reseeded to: o Determine the effect of lignin on cellulose utilization; and · Evaluate pretreatment needs for specific substrates such as bagasse, waste paper, and various woods. References and Suggested Reading Vo/variella Species Chang, S. T. 1965. How to grow straw mushrooms. Quarterly Journal of the Taiwan Museu m (Taipei). 1 8: 4 7 7-4 8 7. 1977. The straw mushroom as a good source of food protein in Southeast Asia. Paper presented at the Fifth International Conference on Global Impacts of Applied Microbiology, November 21-25, 1977, Bangkok, Thailand. , and Hayes, W. A. 1978. The biology and cultivation of edible mushrooms. New York: Academic Press. Chua, S. E., and Ho, S. Y. 1973. Cultivation of straw mushrooms. World Crops 25:90- 91. Gray, W. D. 1970. The use of fungi as food and in food processing. West Palm Beach, Florida: CRC Press. Ho, Ming-shu. 1972. Straw mushroom cultivation in plastic houses. Mushroom Science 8: 257-263. Singer, R. 1961. Mushrooms and truffles. Bedfordshire, England: Leonard Hill Books distributed in the United States by John Wiley and Sons (World Crop Books), New York. , Len tin us edodes Species Akiyama, H.; Akiyama, R.; Akiyama, I.; Kato, A.; and Nakazawa, K. 1974. The new cultivation of shiitake in a short period. Mushroom Science 9:423-434. Gray, W. D. 1970. The use of fungi as food and in food processing. West Palm Beach, Florida: CRC Press. Singer, R. 1961. Mushrooms and truffles. Bedfordshire, England: Leonard Hill Books, distributed in the United States by John Wiley and Sons (World Crop Books), New York. Pleurotus Species Block, S. S., et al. 1959. Experiments in the cultivation of Pleurotus ostreatus. Mush- room Science 4:309-325. Gray, W. D. 1970. The use of fungi as food and in food processing. West Palm Beach, Florida: CRC Press. Kaneshiro, T. 1976. Lignocellulosic agricultural wastes degraded by Pleurotus ostreatus. Developments in Industrial Microbiology 18:591-597.
CELLULOSE CONVERSION 155 Singer, R. 1961. Mushrooms and truffles. Bedfordshire, England: Leonard Hill Books, distributed in the United States by John Wiley and Sons (World Crop Books), New York. Zadrazil, F. 1976. The ecology and industrial production of Pleurotus ostreatus, P. florida, P. cornucopian, and P. eryngii. Mushroom Science (London) 9 (Part-1): 621-652. Thermoactinomyces Species Bellamy, W. D. 1974. Single cell proteins from cellulosic wastes. Biotechnology and Bioengzneering 16:869. . 1976. Production of single-cell protein for animal feed from lignocellulose wastes. World Animal Review 18: 39. . 1977. Cellulose and lignocellulose digestion by thermophilic actinomyces for single-cell protein production. Developments in Industrial Microbiology 8:249-254. Blyth, E. 1973. Farmer's lung disease in actinomvcetales. In Actinr~mvretal~.v rharart~r- ,, ~ . . . . istics and practical importance, G. S. Sykes and F. A. Skinner, eds., pp. 261-276. New York: Academic Press. Crawford, D. L. 1974. Growth of Thermomonospora fusca on lignocellulose pulps of varying lignin content. Canadian Journal of Micro biology 20:1069-1072. ; E. McCoy; J. M. Harkin; and P. Jones. 1973. Production of microbial protein from waste cellulose by Thermomonospora fusca, a thermophilic actinomycete. Bio- technology and Bioengzneering 14:833-843. Gray, W. D. 1970. The use of fungi as food and in food processing. West Palm Beach, Florida: CRC Press. Hesseltine, C. W. 1972. Solid state fermentations. Biotechnology and Bioengineering 14:517-532. Imrie, F. 1975. Single-cell protein from agricultural wastes. New Scientist 66:458. Stutzenberger, F. J. 1972. Cellulolytic activity of Thermomonospora curvata: nutritional requirements for cellulase production Applied Microbiology 24:77-82. Terui, G.; Shibasaki, I.; and Mochiguki T. 1958. Studies on high-heap aeration process as applied to some industrial fermentations: II. General description of the improved process. Osaka University Technology Reports 3: 214. Phanerochaete chrysosporium Ander, P., and Eriksson, K.-E. 1977. Lignin degradation and utilization by microorgan- isms. Archives of Microbiology 109:1-15. Burdsall, H. H., Jr., and Eslyn, W. E. 1974. A new Phanerochaete with a Chrysosponum imperfect state. Mycotaxon 1 :123-133. Eriksson, K.-E., and Pettersson, B. 1972. Extracellular enzyme system utilized by the fungus Chrysosporium li~corum for the breakdown of cellulose. In Biodetenoration of materials: Proceedings of the International Biodeterioration Symposium, 2nd, Lunteren, The Netherlands. A. Harry Walters and E. H. Hueck-Van Der Plas, eds., Vol. 2, pp. 116-120. New York: John Wiley and Sons. Hofsten, B. V., and Hofsten, A. V. 1974. Ultrastructure of a thermotolerant basidio- mycete possibly suitable for production of food protein. Applied Microbiology 27:1 142-1 148. Kirk, T. K.; Yang, H. H.; and Keyser, P. 1978. The chemistry and physiology of the fungal degradation of lignin. In Developments in Industrial Microbiology, Proceedings of the Annual Meeting, August 21-26, 1977, Michigan State University, Lansing, Michigan, L. A. Underkofler, ea., pp. 51-61. Arlington, Virginia: American Institute of Biological Sciences. Trichoderma reesei Gaden, E. L., Jr.; Mandels, M.; Reese, E. T.; and Spano, L. A., eds. 1976. Enzymatic conversion of cellulosic materials: technology and applications. New York: John Wiley and Sons.
156 MICROBIAL PROCESSES Mandels, M., and Web er, J. 1969. The production of cellulases. In Cellulases and their application. Advances in Chemistry Series, No. 95, pp. 391-414. Washington, D.C.: American Chemical Society. Other Species Bruit, C., and Kushner, J. J. 1976. Cellulase induction and the use of cellulose as a preferred growth substrate by Cellvibrio gilvus. Canadian Journal of A'ficrobiology 22: 1777-1787. Dunlop, C. E. 1975. Production of single-cell protein from insoluble agricultural wastes by mesophiles. In Single-cell protein II. S. R. Tannenbaum and D. E. Wana. eds.. 7 ~ ~ _ _ ~ ~ ~ pp. 244-267. Cambridge, Massachusetts: Massachusetts Institute of Technology Press. Han, Y. W., and Callihan, C. D. 1974. Cellulose fermentation: effect of substrate pre- treatment on microbial growth. Applied Microbiology 27:159-165. Thayer, D. W. 1976. A submerged culture process for production of cattle feed from mesquite wood. Developments in Industrial Microbiology 17: 1779-1789. Research Contacts and Culture Sources Volveriella Species Romeo V. Alicbusan, Science Research Supervisor and Head, Microbiological Research Department, National Institute of Science and Technology, Manila, lThe Philippines. S. T. Chang, Department of Biology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong. Yoshio Hashioka, 2337 Shinkano Naka, Kagamigahara City, Gifu, Japan James P. San Antonio, Genetics and Germ Plasm Institute, Vegetable Laboratory, BARC-W, U.S. Department of Agriculture, Science and Education Administration, Beltsville, Maryland 20705, U.S.A. Lung-chi Wu, Campbell Institute for Agricultural Research, Napoleon, Ohio 43545, U.S.A. Pleurotus Species Gerlind Eger, Institut fux Pharmazeutische Technologie, Universitat Marburg, Marbacher Weg 6, 355 Marburg, West Germany. S. C. Jong, Mycology Department, American Tvne. C~,lt',re. (~nile.r~tinn Drive. Rockville. Marvland 28052 U.S.A. ~ .r r~ .. , 12301 Parklawn 7 ~ J. T. Peng, Mushroom Research Laboratory, Taiwan Agricultural Research Institute, Taipei, Taiwan, R.O.C. James P. San Antonio, Genetics and Germ Plasm Institute, Vegetable Laboratory, BARC-W, U.S. Department of Agriculture, Science and Education Administration, Beltsville, Maryland 20705, U.S.A. Thermoactinomyces Species Cellulose- or starchutilizing thermophilic actinomycetes can easily be isolated from any compost pile by culturing on starch agar or cellulose agar plates at 55°- 65°C. W. D. Bellamy, Department of Food Science, Cornell University, Ithaca, New York, 14853, U.S.A. D. L. Crawford, Department of Bacteriology and Biochemistry, University of Idaho, Moscow, Idaho 83843, U.S.A. Phanerochaete chrysosporium Karl-Erik Eriksson, Swedish Forest Products Research Laboratory, Noc 5064, S-114 86 Stockholm, Sweden.
CELLULOSE CONVERSION 157 T. Kent Kirk, Forest Service, U.S. Department of Agriculture, Forest Products Labora- tory, P.O. Box 5130, Madison, Wisconsin 53705, U.S.A. Trichoderma reesei Elwyn Reese, Food Science Laboratory, U.S. Army, Natick Research and Development Command, Natick, Massachusetts 01760, U.S.A. Other Species V. R. Srinivasan, Department of Microbiology, Louisiana State University, Baton Rouge, Louisiana 70803, U.S.A. D. W. Thayer, Department of Biological Sciences and Food Nutrition, Texas Tech- nological University, Lubbock, Texas 79409, U.S.A.
