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Fermentation of cellulosic substrates in batch and continuous culture by Clostridium thermocellum

Lynd, L.R. (Dartmouth College, Hanover, New Hampshire MI) ; Grethlein, H.E ; Wolkin, R.H

Applied and Environmental Microbiology, 1989-12, Vol.55 (12), p.3131-3139 [Periódico revisado por pares]

Washington, DC: American Society for Microbiology

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Título:
Fermentation of cellulosic substrates in batch and continuous culture by Clostridium thermocellum
Autor: Lynd, L.R. (Dartmouth College, Hanover, New Hampshire MI) ; Grethlein, H.E ; Wolkin, R.H
Assuntos: 09 BIOMASS FUELS ; ACETATES ; acetic acid ; ACTIVIDAD ENZIMATICA ; ACTIVITE ENZYMATIQUE ; ALCOHOLES ; ALCOHOLS ; ALCOOL ; BACTERIA ; BATCH CULTURE ; BIOCONVERSION ; Biological and medical sciences ; BIOSINTESIS ; BIOSYNTHESE ; BIOSYNTHESIS ; Biotechnology ; BOIS DE FEUILLUS ; CARBOHYDRATES ; CARBOXYLIC ACID SALTS ; cellulase ; CELLULOSE ; CELULOSA ; CLOSTRIDIUM ; CLOSTRIDIUM THERMOCELLUM ; CONTINUOUS CULTURE ; ETHANOL ; FARINE DE BOIS ; FERMENTACION ; FERMENTATION ; Fundamental and applied biological sciences. Psychology ; HARINA DE MADERA ; HYDROXY COMPOUNDS ; MADERA DE FRONDOSAS ; Methods. Procedures. Technologies ; Microbial engineering. Fermentation and microbial culture technology ; MICROORGANISMS ; ORGANIC COMPOUNDS ; Physiology and Biotechnology ; POLYSACCHARIDES ; PRODUCTIVITY ; SACCHARIDES ; SYNTHESIS 090900 -- Biomass Fuels-- Processing-- (1990-)
É parte de: Applied and Environmental Microbiology, 1989-12, Vol.55 (12), p.3131-3139
Notas: 9026996
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Present address: Colgate Juvenile Products, 712 Ponce de Leon Place, Atlanta, GA 30306.
Present address: Michigan Biotechnology Institute, 3900 Collins Road, Lansing, MI 48909.
Corresponding author.
Descrição: Fermentation of dilute-acid-pretreated mixed hardwood and Avicel by Clostridium thermocellum was compared in batch and continuous cultures. Maximum specific growth rates per hour obtained on cellulosic substrates were 0.1 in batch culture and greater than 0.13 in continuous culture. Cell yields (grams of cells per gram of substrate) in batch culture were 0.17 for pretreated wood and 0.15 for Avicel. Ethanol and acetate were the main products observed under all conditions. Ethanol:acetate ratios (in grams) were approximately 1.8:1 in batch culture and generally slightly less than 1:1 in continuous culture. Utilization of cellulosic substrates was essentially complete in batch culture. A prolonged lag phase was initially observed in batch culture on pretreated wood; the length of the lag phase could be shortened by addition of cell-free spent medium. In continuous culture with approximately 5 g of glucose equivalent per liter in the feed, substrate conversion relative to theorectical ranged from 0.86 at a dilution rate (D) of 0.05/h to 0.48 at a D of 0.167/h for Avicel and from 0.75 at a D of 0.05/h to 0.43 at a D of 0.11/h for pretreated wood. At feed concentrations of less than 4.5 g of glucose equivalent per liter, conversion of pretreated wood was 80 to 90% at D = 0.083/h. Lower conversion was obtained at higher feed substrate concentrations, consistent with a limiting factor other than cellulose. Free Avicelase activities of 12 to 84 mU/ml were observed, with activity increasing in this order: batch cellobiose, batch pretreated wood less than batch Avicel, continuous pretreated wood less than continuous Avicel. Free cellulase activity was higher at increasing extents of substrate utilization for both pretreated wood and Avicel under all conditions tested. The results indicate that fermentation parameters, with the exception of free cellulose activity, are essentially the same for pretreated mixed hardwood and Avicel under a variety of conditions. Hydrolysis yields obtained with C. thermocellum cellulase acting either in vitro or in vivo were comparable to those previously reported for Trichoderma reesei on the same substrates
Editor: Washington, DC: American Society for Microbiology
Idioma: Inglês

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Fermentation of cellulosic substrates in batch and continuous culture by Clostridium thermocellum

Lynd, L.R. (Dartmouth College, Hanover, New Hampshire MI) ; Grethlein, H.E ; Wolkin, R.H

Washington, DC: American Society for Microbiology

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