Production of ethanol from pulp mill hardwood and softwood spent sulfite liquors by genetically engineered E. coli

Journal Article · · Applied Biochemistry and Biotechnology; (United States)

DOI:https://doi.org/10.1007/BF02919027· OSTI ID:6503350

Lawford, H G; Rousseau, J D ^[1]

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1. Univ. of Toronto, Ontario (Canada)

Although lignocellulosic biomass and wastes are targeted as an attractive alternative fermentation feedstock for the production of fuel ethanol, cellulosic ethanol is not yet an industrial reality because of problems in bioconversion technologies relating both to depolymerization and fermentation. In the production of wood pulp by the sulfite process, about 50% of the wood (hemicellulose and lignin) is dissolved to produce cellulose pulp, and the pulp mill effluent ([open quotes]spent sulfite liquor[close quotes] SSL) represents the only lignocellulosic hydrolysate available today in large quantities. Although softwoods have been the traditional feedstock for pulping operations, hardwood pulping is becoming more popular, and the pentose sugars in hardwood SSL (principally xylose) are not fermented by the yeasts currently being used in the production of ethanol from softwood SSL. This study assessed the fermentation performance characteristics of a patented (US Pat. 5,000,000), recombinant Escherichia coli B (ATCC 11303 pLOI297) in anaerobic batch fermentations of both nutrient-supplemented soft and hardwood SSL (30-35 g/L total reducing sugars). The pH was controlled at 7.0 to maximize tolerance to acetic acid. In contrast to the high-performance characteristics exhibited in synthetic media, formulated to mimic the composition of softwood and hardwood SSL, performance in SSL media was variable with conversion efficiencies in the range of 67-84% for hardwood SSL and 53-76% for softwood SSL. Overlimiting treatment of HSSL, using Ca(OH)[sub 2], improved overall volumetric productivity two- to sevenfold to a max of 0.42 g/L/h at an initial cell loading of 0.5 g dry wt/L. A conversion efficiency of 92% was achieved using diluted Ca(OH)[sub 2]-treated hardwood SSL. The variable behavior of this particular genetic construct is viewed as a major detractant regarding its candidacy as a biocatalyst for SSL fermentations. 48 refs., 8 figs., 4 tabs.

• OSTI ID: 6503350
• Journal Information: Applied Biochemistry and Biotechnology; (United States), Journal Name: Applied Biochemistry and Biotechnology; (United States) Vol. 39-40; ISSN ABIBDL; ISSN 0273-2289
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
090900* -- Biomass Fuels-- Processing-- (1990-)
ALCOHOL FUELS
BACTERIA
BIOCONVERSION
BIOLOGICAL PATHWAYS
ESCHERICHIA COLI
ETHANOL FUELS
FERMENTATION
FUELS
INDUSTRIAL WASTES
LIQUID WASTES
MICROORGANISMS
PRODUCTION
SOLID WASTES
SPENT LIQUORS
SYNTHETIC FUELS
WASTES
WOOD WASTES