Method for producing ethanol from xylose-containing substance

Details Method for producing ethanol from xylose-containing substance Method for producing ethanol from xylose-containing substance

1984-12-31

1987-10-20

Penland, R. B.

Chemistry: molecular biology and microbiology

Micro-organism, tissue cell culture or enzyme using process...

Preparing oxygen-containing organic compound

435161, 435938, 435921, 435801, C12P 708

Patent

active

047014148

DESCRIPTION:

BRIEF SUMMARY
This invention relates to a method for producing ethanol from a xylose-containing substance, comprising fermenting said substance with a yeast. Such methods have been disclosed recently in the U.S. Pat. Nos. 4,359,534 and 4,368,268, wherein the fermentation utilizes the yeast Pachysolen tannophilus and yeast mutants from the strain Candida sp. The obejct of the present invention is to provide a method for fermenting xylose in a high yield.
The yeasts for use in the invention are Pichia stipitis, Pichia segobiensis and Candida shehatae. The P. stipitis type strain CBS 5773 (NRRL Y-7124, T) was originally isolated from an insect larvae and was designated by Pignal. The standard description of P. stipitis, made by Kreger-van Rij, 1970 (The Yeasts-A Taxonomic Study (Lodder, J. ed.) pp. 533-535, North-Holland Publishing Company-Amsterdam, London) is as follows:
Growth in malt extract: After 3 days at 25.degree. C. the cells are spherical to oval (2-7.5).times.2.5-7.5) .mu.m; single or in pairs. A sediment is formed. After one month at 17.degree. C. a sediment and, occasionally, a ring are present.
Growth on malt agar: After 3 days at 25.degree. C. the cells are spherical to short-oval, (2.5-4.5).times.(2.5-6) .mu.m; single or in pairs. Pseudomycelial cells may occur up to 15 .mu.m long. After one month at 17.degree. C. the streak culture is cream-colored, occasionally with a reddish tinge, soft, smooth or delicately wrinkled in the middle, and semiglossy. The edge is fringed with pseudomycelium.
Slide cultures on potato- and corn meal agar: Pseudomycelium is abundantly formed. It is more or less branched and consists of long pseudomycelial cells with small blastospores.
Formation of ascospores: Conjugation between mother cell and bud or between two single cells precedes ascus formation. The cells may form protuberances of various lengths. The spores are hat-shaped; two are formed per ascus. They are easily liberated from the ascus. Spores were observed in the three strains studied on YM-, Difco malt extract- and corn meal agar.
Fermentation:


______________________________________ Glucose + (slow) Trehalose + (very weak) or - Galactose + (slow) Lactose - Sucrose - Raffinose - Maltose + (slow) ______________________________________
Assimilation of carbon compounds:


______________________________________ Glucose + D-Ribose + Galactose + L-Rhamnose + L-Sorbose - Ethanol + Sucrose + Glycerol + Maltose + Erythritol + Cellobiose + Ribitol + Trehalose + Galactitol - Lactose + D-Mannitol + Melibiose - D-Glucitol + Raffinose - .alpha.-Methyl-D-glucoside + Melezitose + Salicin + Inulin - DL-Lactic acid + Soluble starch + Succinic acid + D-Xylose + Citric acid + L-Arabinose + Inositol - D-Arabinose - ______________________________________
In addition to the above-mentioned fermentable substrates it has unexpectedly been found that P. stipitis also ferments D-xylose. P. segobiensis is described in the following reference: J. Santa Maria and G. G. Aser, An. Inst. Nac. Invest. Agrarias, Ser. General 5 (1977) 45-50. It has been found that this yeast ferments D-xylose to ethanol to a degree comparable to that of P. stipitis. All P. stipitis strains tested--CBS 5773, CBS 5774, CBS 5775, CBS 5776, CBS 6054, and P. segobiensis strain CBS 6857--share this characteristic. All these strains are therefore contemplated for use in the disclosed process. Also the tentatively (Lodder: The Yeasts (1970) p. 535, 1046, 1047) imperfect form of P. stipitis (Candida shehatae) ferments D-xylose to ethanol and is therefore also contemplated for use in the disclosed process.
All D-xylose-containing substrates are suitable in the disclosed process provided they do not contain any constituents which are severely inhibitory to the process.
Since available glucose also will be fermented to ethanol, hydrolyzed cellulose and hydrolyzed hemicellulose or mixtures thereof are particularly suited as substrates in the disclosed process. Hence, as raw material for the process could se

REFERENCES:
patent: 4359534 (1982-11-01), Kurtzman et al.
patent: 4368268 (1983-01-01), Gong
patent: 4477569 (1984-10-01), Schneider et al.
patent: 4511656 (1985-04-01), Gong
Du Preg, "Fermentation of Dxylose to Ethanol by A Strain of Candida Shehatae", Chemical Abstracts, vol. 99, Abstract No. 20889u, (1983).
Inst. Ferm. Research, "Ethanol Production from Xylose", Chemical Abstracts, vol. 100, Abstract No. 4808a, (1984).
Bruinenberg et al., "NADH Linked Aldose Reduclose the Key to Anaerobic Alcohol Fermentation of Xylose by Yeasts", Chem Abst 101: 128823s.
Toivola et al., Alcoholic Fermentation of D-Xylose by Yeasts, Chemical Abstracts, vol. 101, Abstract No. 70990a, (1984).
Maleszka et al., "Yeasts that Ferment D-Cellobiose As Well As D-Xylose", Biotechnology Letters, vol. 4, pp. 133-136 (1982).

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