Methods for increasing the production of ethanol from microbial fermentation
First Claim
1. A continuous method for producing ethanol from the anaerobic bacterial fermentation of a gaseous substrate comprising carbon monoxide, the method comprising:
- culturing in a fermentation bioreactor anaerobic, acetogenic C. ljungdahlii bacteria in a continuously fed liquid nutrient medium to provide a fermentation broth and supplying to said fermentation bioreactor said gaseous substrate comprising carbon monoxide (CO);
maintaining a specific rate of CO uptake in said fermentation bioreactor at an amount of 0.3 to 2 mmol CO/gram dry cells weight of bacteria/minute in the fermentation broth after said bacteria achieve a stable cell concentration in said fermentation bioreactor, wherein said free acetic acid concentration in said fermentation bioreactor is less than 5 g/L free acetic acid,producing ethanol in a fermentation broth at a productivity greater than 10 g/L per day; and
producing both ethanol and acetate in said fermentation broth in a ratio of ethanol to acetate ranging from 1;
1 to 20;
1.
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Abstract
A stable continuous method for producing ethanol from the anaerobic bacterial fermentation of a gaseous substrate containing at least one reducing gas involves culturing a fermentation bioreactor anaerobic, acetogenic bacteria in a liquid nutrient medium; supplying the gaseous substrate to the bioreactor; and manipulating the bacteria in the bioreactor by reducing the redox potential, or increasing the NAD(P)H TO NAD(P) ratio, in the fermentation broth after the bacteria achieves a steady state and stable cell concentration in the bioreactor. The free acetic acid concentration in the bioreactor is maintained at less than 5 g/L free acid. This method allows ethanol to be produced in the fermentation broth in the bioreactor at a productivity greater than 10 g/L per day. Both ethanol and acetate are produced in a ratio of ethanol to acetate ranging from 1:1 to 20:1.
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Citations
22 Claims
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1. A continuous method for producing ethanol from the anaerobic bacterial fermentation of a gaseous substrate comprising carbon monoxide, the method comprising:
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culturing in a fermentation bioreactor anaerobic, acetogenic C. ljungdahlii bacteria in a continuously fed liquid nutrient medium to provide a fermentation broth and supplying to said fermentation bioreactor said gaseous substrate comprising carbon monoxide (CO); maintaining a specific rate of CO uptake in said fermentation bioreactor at an amount of 0.3 to 2 mmol CO/gram dry cells weight of bacteria/minute in the fermentation broth after said bacteria achieve a stable cell concentration in said fermentation bioreactor, wherein said free acetic acid concentration in said fermentation bioreactor is less than 5 g/L free acetic acid, producing ethanol in a fermentation broth at a productivity greater than 10 g/L per day; and producing both ethanol and acetate in said fermentation broth in a ratio of ethanol to acetate ranging from 1;
1 to 20;
1. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification
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- Resources
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Current AssigneeJupeng Bio (HK) Limited
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Original AssigneeEmmaus Foundation, Inc.
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InventorsKo, Ching-Whan, Basu, Rahul, Wikstrom, Carl V., Gaddy, James L., Arora, Dinesh K., Clausen, Edgar C., Phillips, John Randall
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Primary Examiner(s)Marx; Irene
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Application NumberUS10/311,655Publication NumberTime in Patent Office2,283 DaysField of SearchNoneUS Class Current435/161CPC Class CodesC12M 21/04 for producing gas, e.g. bio...C12M 21/12 for producing fuels or solv...C12M 29/02 PercolationC12M 29/18 External loop; Means for re...C12M 43/02 Bioreactors or fermenters c...C12P 7/065 with microorganisms other t...Y02E 50/10 Biofuels, e.g. bio-dieselY02E 50/30 Fuel from waste, e.g. synth...
