Mutant strain of C. acetobutylicum and process for making butanol

DETAILED DESCRIPTION We claim: 1.
A method of producing butanol which comprises anaerobically culturing a biologically pure culture of Clostridium acetobutylicum ATCC 55025 in a nutrient medium with assimilable sources of carbon, nitrogen, and inorganic substances and then recovering the butanol.
2.
A biologically pure culture of clostridium acetobutylicum ATCC 55025.




Description:
FIELD OF THE INVENTION The present invention relates to a Novel mutant strain of Clostridium acetobutylicum and a fermentation process for producing butanol using that mutant strain.
BACKGROUND OF THE INVENTION Diminishing petroleum resources have made the search for alternative fuel and chemical feedstock sources increasingly important.
Butanol, in addition to its many uses as a chemical feedstock, is among the alternatives.
The acetone/butanol/ethanol (ABE) fermentation, therefore, has received considerable attention in recent years as a prospective process for production of commodity chemicals from biomass.
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3,6 ABE fermentations are biphasic.
During the first (acidogenic) phase logarithmic growth is accompanied by acetic and butyric acid production which also causes a drop in pH.
In the second (solventogenic) phase growth ceases and the solvents (ABE) are produced concomitant with consumption of already produced acids and further consumption of the carbohydrates.
Hydrogen and carbon dioxide are produced throughout the fermentation.
Traditionally, the commercial ABE fermentation was conducted only in a batch mode due to culture instability and spore-forming nature of the organism.
Several solvent-yielding fermentation processes using batch or continuous cultures.
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2,4,7, chemostats with cell recycling.
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1 or immobilized cell systems.
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5 have been described.
These processes yield butanol, acetone and ethanol in a ratio of 6:3:1.
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11.
Mixed solvent yields of 29-33% of fermentable carbohydrate have been reported in the literature.
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12 A total solvent concentration of about 16-20 g/L and a butanol concentration of 10-12 g/L is generally the limit due to toxicity of the butanol produced