Gums Produced by Fungi Industrial Utilization J. R. SANBORN' Arthur D. Little, Inc.,Cambridge, Mass.
B
OTAKICAL literature is rich in referenceb to uses of fungi as food and also in the manufacture of many useful products. In the Orient there is extensive cultivation of fungi for edible purposes (1). The palatability and possible nutritive value of growth agglomerates produced by many types of microorganism have aroused widespread interest (4, 6, 7 , 11). Investigations have revealed the special value of the carbohydrates, fats, proteins, minerals, growth accessory factors, and aromatic and flavoring substances produced by fungi. Although the formations of higher fungi have, in the past. received major consideration, the agglomerates constructed by filamentous fungi, yeastlike forms, and bacteria undoubtedly hold far greater economic possibilities. The comparative eaie of cultivation and control over conditions of growth and production renders the utilization of lower fungi distinctly advantageous. The object of this paper is to bring to the attention of workers in industrial microbiology the value of fungus growth masses and the feasibility and economy of processes for their utilization. These masses include gelatinous, slimy, viscous, leathery, or rubbery growth formations, many of which are commonly referred to as gums.
Utilization of Fungus Agglomerates Pellicles produced by several species have long been recognized as a source of commercially valuable products. It has also been known that fleshy bracket fungi can be converted into a pulp suitable for the production of useful films and membranes. Fungi of this type have been dried, reduced to a fine powder, and agitated with iolvents forming uniform, rubber-like masseq ( 8 ) . A method developed in Germany for the manufacture of a leather substitute from tanned membranes composed of microorganisms utilized such species as Bacterium xylinum (Acetobarter xylinus), Bacterium xylinoides, and Mucor boidin (6). Early observations also indicated the possibility of producing from slimy growths semi-transparent, parchment-like sheetq. Pioneers in the art of paper-making noted the behavior of objectionable maSses of gum or slime carried by pulp streams to papermaking machine.. occasionally resulting in the conversion of such niasqes to glazed, semi-transparent 1
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films frequently apparent in finished paper. Species belonging to the genera Mucor, Penicillium, Oidium, and Monilia are often responsible for objectionable formations. Cultivated in media composed of inexpensive ingredients, certain of these types produce abundant quantities of gum.: possesing economically useful properties. A number of yeastlike fungi admirably adapted to commercial cultivation have already been utilized in the production of semi-transparent sheets (9,10). Growth masses develop rapidly in the form of gelatinous clots and, during the first four weeks of incubation, may be used for sheet manufacture. Gums a t this stage are rubbery, compact, and eaqily manipulated. Older cultures become sticky and difficult to handle. A preferred species, resembling Oidium Zactis, produces high yields of gum from glucose, glycerol, and mannose. Laboratory culture. in potato decoction and glycerol form, in four weeks from 200 cc. of this medium in shallow layers, thick growth masses weighing 80 to 100 grams. These growths are gelatinous, containing approximately 90 per cent of water. iilthough thi. organiim has not been cultivated commercially, it is reasonable to expect that yields on a plant vale nill, on a coinparal)le ba*ic, be considerably larger. 1189
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Gum Yields from Various Media Although certain types of pellicle become characteristically hard and matted, the gelatinous clot produced by this gumforming Oidium has an important bearing upon further commercial applications. For example, the gum suspension may, through its gelatinizing action, materially enhance the usefulness of many fibrous structures. In fulfilling this function, adhesive and cohesive properties are usually combined. Properly manipulated and applied, the suspensions provide mucilaginous surfaces for finely divided coating material..
YIELDS OFOlDlUM GUM IN VARfOUS MEDIA POTATO DECOCTION. 200 CC(FRITZ.3) r
DO.+ LACTOSE
10%
DO.+ SUCROSE 10% DO.* D E X T R I N
IO$
DO.+ MALTOSE
IOd
DO.+ ETHYL ALCOHOL 3% FINE SLOP FROM STARCH
Used as intermediate layer.*, they bind efficiently sheets Of widely varying types. In much of this work advantage is taken of the valuable i n d a t i n g properties possessed by certain types of fungus grnwth. Search for microorganisms whose growth agglomerates present favorable possibilities for industrial uses invariably reveals numerous species which grow in rank profusion upon certain laborat'ory media. The isolations may include gummy varieties of such organiwis a- Escherichia leporis. Aerobacter aerogenes, Bacillus vulgatus, Oidium lactis, Oidium pullulans, Monilia candida, Aspergillus fumigatus, Mucor racernosus, Penicillium guttulosuin. The synthetic activitieof yeasts, because of their intinlate relation to the coii>triic.tive processes under consideration and t,heir close asociaticiii in food preparation with other orgaiii.qnis, mnit also figure prominently in industrial utilization. Indeed, the enorinoils developments in manufacture of yeast' is one of the conspicuous advances in food industrieF. In 1930 it TVRS reportd that
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the total production in this country of compressed yeast equaled 230 million pounds per year ( 2 ) . The figure for 1931, which includes yeast and other leavening compounds, approached 335 million pounds (12). Several kinds of low-cost raw materials are available for the cultivation of these organisms, such as waste sulfite liquor. molaqses, distillery slop, cereal mashes, slop from starch manufacture, wood residues, and corn sirup. Potato mash and glucose for the cultivation of Oidium impose a cost of approximately one cent per pound on the freshly prepared agglomerate- containing 90 per cent of water. Although more or lesc coinplete removal of water would effect a substantial increase in cost, some of the uses which have been suggested for the material undoubtedly justify the added expense of handling If additional nitrogen is required, the inorganic forms usually iufice, though wastes from industrial plants may be uqed. It I< poi4ble to describe the growths produced by one or niore of the following terms: stringy, creamy, gelatinous, paqty, doughy, leathery, rubbery, or crusty. The material% may be manipulated or treated to meet the varying demandof indu-try. Cellulose or rubber industries may, for example, find ready uses for gummy products as binders, adhesive*, coating agents, and oil- or grease-proofing media. The value of growth agglomerates in the manufacture of animal feedi ha\ heen repeatedly demonstrated. Positive evidence is alp(, accumulating which points to their peculiar adaptability tu hunian nutrition and food preparation. Results obtainec' Yuggest unusual applications for the future in the manufacture of flavoring or odorous materials and as sources for valuable chemicals. It is even possible to develop certain specialty articlee which may be rendered particularly desirable becauqe of the activities of microorganisms.
Literature Cited Uyson, G. M., Pharm. J.,121, 375 (1928). Frey, c. N., ISD.EXG.CHEM.,22, 1154 (1930). Fritz, Trans. R o y . SOC.Can.,17, 200 (1923). Hellens, 0. v., Finsk. L&kares. Handl., 55,408-34; Zentr. Biochem. Biophus., 15, 483 (1914). Herrog, R. O., U. S.P a t e n t 1,141,545 (1915). Loewy 3nd von der Heide. Berliner klin. Wochschr., 52, IiOO 11915) K a e t h , F. C., U. 5 . P a t e n t 1,632,312 (1927). Russian P a t e n t 11,305 (1926). Sanhorn, J. R., ISD. ESQ. CriEx, 26, 532 (1934). Stinborn, J. R., U.S.P a t e n t 2,026,253 (1935). Skinner, ,J. T., Peterson, W, H.. and Stcenbock. I I . , Rioch,em Z . . 267, 169 (1933). U. S . D e p t . Commerce, Biennial C e n s u ~of Manufactures, 1931. W a c E I Y E D April 3, 1936. This parier represents a portion of a n investiyatlurl conducted in part a t the laboratories of Arthur D. Little, Inc., and i n p a r t by the Research Division of the International Paper Company.
