US4808526A
Expired / Lapsed
US
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Continuous process for ethanol production by bacterial fermentation
Assignee: George Weston Ltd
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Filing: 1985-05-20
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Granted: 1989-02-28
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Expires: 2005-05-20
Abstract
Abstract A continuous process for the production of ethanol by fermentation with strains of Zymomonas is provided. Metabolic processes are limited by the nutrients nitrogen, potassium and phosphorus. When growth is limited by one of these nutrients, the biomass expresses its maximum value for both q s and q p at any given value of D and S r . The process is conducted at a lower biomass concentration and a higher specific rate of ethanol formation than a similar process conducted with a nutrient medium that is not limited in nitrogen, potassium or phosphorus. A method of improving performance of Zymomonas in continuous ethanol fermentation at increased temperatures is also provided.
Inventors
- 👤 Hugh G. Lawford
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 00:05
CPC Classifications
C; C12; C12M; C12M41/00; C12M41/30; C12M41/32; C12P; C12P7/00; C12P7/02; C12P7/04; C12P7/06; C12P7/065; Y; Y02; Y02E; Y02E50/00; Y02E50/10; Y10; Y10S; Y10S435/00; Y10S435/813
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
202 words
A continuous process for the production of ethanol, which comprises feeding an aqueous substrate solution substantially continuously to a fermentation medium containing a submerged culture of an organism of the genus Zymomonas; cultivating said organism under anaerobic conditions in an aqueous nutrient medium containing potassium and assimilable carbon, nitrogen and phosphorus until a recoverable quantity of ethanol is produced; wherein said nutrient medium is limited in assimilable nitrogen such that the rate of growth of said organism is limited by the availability of assimilable nitrogen, and said nutrient medium contains said limiting nutrient in a concentration proportional to dilution rate, such that limiting nutrient concentration is increased as dilution rate increases and is decreased as dilution rate decreases; and wherein said process is conducted as a nutrient-limited fermentation and under conditions such that biomass expresses its maximal value for both q s and q p under conditions of nutrient limitation and said process is conducted at a lower biomass concentration and a higher specific rate of ethanol formation that a similar process conducted with a nutrient medium containing nitrogen in excess; and wherein each of said processes is carried out at the same fermentation temperature, dilution rate and concentration of assimilable carbon.
Claim 2
Dependent Claim
202 words
A continuous process for the production of ethanol, which comprises feeding an aqueous substrate solution substantially continuously to a fermentation medium containing a submerged culture of an organism of the genus Zymomonas; cultivating said organism under anaerobic conditions in an aqueous nutrient medium containing potassium and assimilable carbon, nitrogen and phosphorus until a recoverable quantity of ethanol is produced; wherein said nutrient medium is limited in assimilable nitrogen such that the rate of growth of said organism is limited by the availability of assimilable nitrogen, and said nutrient medium contains said limiting nutrient in a concentration proportional to dilution rate, such that limiting nutrient concentration is increased as dilution rate increases and is decreased as dilution rate decreases; and wherein said process is conducted as a nutrient-limited fermentation and under conditions such that biomass expresses its maximal value for both q s and q p under conditions of nutrient limitation and said process is conducted at a lower biomass concentration and a higher specific rate of ethanol formation that a similar process conducted with a nutrient medium containing nitrogen in excess; and wherein each of said processes is carried out at the same fermentation temperature, dilution rate and concentration of assimilable carbon.
Claim 3
Dependent Claim
33 words
Process according to claim 1 wherein fermentation is conducted at a temperature of about 27° C. to about 37° C. in a fermentation medium having a pH of about 4.5 to about 6.5.
Claim 4
Dependent Claim
14 words
Process according to claim 2 wherein said organism is Z. mobilis strain ATCC 29191.
Claim 5
Dependent Claim
28 words
Process according to claim 2 wherein said substrate is comprised of glucose and the substrate concentration in the fermentation medium is about 100 g/L to about 180 g/L.
Claim 6
Dependent Claim
15 words
Process according to claim 4 wherein effluent from the process is substantially free of substrate.
Claim 7
Dependent Claim
21 words
Process according to claim 4 wherein concentration of ethanol in the fermentation medium is about 50 g/L to about 60 g/L.
Claim 8
Dependent Claim
18 words
Process according to claim 1 wherein said nitrogen is derived from ammonium chloride, ammonium sulphate or mixtures thereof.
Claim 9
Dependent Claim
201 words
A continuous process for the production of ethanol, which comprises feeding an aqueous substrate solution substantially continuously to a fermentation medium containing a submerged culture of an organism of the genus Zymomonas; cultivating said organism under anaerobic conditions in an aqueous nutrient medium containing potassium and assimilable carbon, nitrogen and phosphorus until a recoverable quantity of ethanol is produced; wherein said nutrient medium is limited in potassium, such that the rate of growth of said organism is limited by the availability of assimilable potassium, and said nutrient medium contains said limiting nutrient in a concentration proportional to dilution rate, such that limiting nutrient concentration is increased as dilution rate increases and is decreased as dilution rate decreases; and wherein said process is conducted as a nutrient-limited fermentation and under conditions such that biomass expresses its maximal value for both q s and q p under conditions of nutrient limitation and said process is conducted at a lower biomass concentration and a higher specific rate of ethanol formation than a similar process conducted with a nutrient medium containing potassium in excess; and wherein each of said processes is carried out at the same fermentation temperature, dilution rate and concentration of assimilable carbon.
Claim 10
Dependent Claim
201 words
A continuous process for the production of ethanol, which comprises feeding an aqueous substrate solution substantially continuously to a fermentation medium containing a submerged culture of an organism of the genus Zymomonas; cultivating said organism under anaerobic conditions in an aqueous nutrient medium containing potassium and assimilable carbon, nitrogen and phosphorus until a recoverable quantity of ethanol is produced; wherein said nutrient medium is limited in potassium, such that the rate of growth of said organism is limited by the availability of assimilable potassium, and said nutrient medium contains said limiting nutrient in a concentration proportional to dilution rate, such that limiting nutrient concentration is increased as dilution rate increases and is decreased as dilution rate decreases; and wherein said process is conducted as a nutrient-limited fermentation and under conditions such that biomass expresses its maximal value for both q s and q p under conditions of nutrient limitation and said process is conducted at a lower biomass concentration and a higher specific rate of ethanol formation than a similar process conducted with a nutrient medium containing potassium in excess; and wherein each of said processes is carried out at the same fermentation temperature, dilution rate and concentration of assimilable carbon.
Claim 11
Dependent Claim
33 words
Process according to claim 8 wherein fermentation is conducted at a temperature of about 27° C. to about 37° C. in a fermentation medium having a pH of about 4.5 to about 6.5.
Claim 12
Dependent Claim
14 words
Process according to claim 9 wherein said organism is Z. mobilis strain ATCC 29191.
Claim 13
Dependent Claim
28 words
Process according to claim 9 wherein said substrate is comprised of glucose and the substrate concentration in the fermentation medium is about 100 g/L to about 180 g/L.
Claim 14
Dependent Claim
15 words
Process according to claim 11 wherein effluent from the process is substantially free of substrate.
Claim 15
Dependent Claim
21 words
Process according to claim 11 wherein concentration of ethanol in the fermentation medium is about 50 g/L to about 60 g/L.
Claim 16
Dependent Claim
12 words
Process according to claim 8 wherein said potassium is derived from KCl.
Claim 17
Dependent Claim
201 words
A continuous process for the production of ethanol, which comprises feeding an aqueous substrate solution substantially continuously to a fermentation medium containing a submerged culture of an organism of the genus Zymomonas; cultivating said organism under anaerobic conditions in an aqueous nutrient medium containing potassium and assimilable carbon, nitrogen and phosphorus until a recoverable quantity of ethanol is produced; wherein said nutrient medium is limited in phosphorus such that the rate of growth of said organism is limited by the availability of assimilable phosphorus, and said nutrient medium contains said limiting nutrient in a concentration proportional to dilution rate, such that limiting nutrient concentration is increased as dilution rate increases and is decreased as dilution rate decreases; and wherein said process is conducted as a nutrient-limited fermentation and under conditions such that biomass expresses its maximal value for both q s and q p under conditions of nutrient limitation and said process is conducted at a lower biomass concentration and a higher specific rate of ethanol formation than a similar process conducted with a nutrient medium containing phosphorus in excess; and wherein each of said processes is carried out at the same fermentation temperature, dilution rate and concentration of assimilable carbon.
Claim 18
Dependent Claim
201 words
A continuous process for the production of ethanol, which comprises feeding an aqueous substrate solution substantially continuously to a fermentation medium containing a submerged culture of an organism of the genus Zymomonas; cultivating said organism under anaerobic conditions in an aqueous nutrient medium containing potassium and assimilable carbon, nitrogen and phosphorus until a recoverable quantity of ethanol is produced; wherein said nutrient medium is limited in phosphorus such that the rate of growth of said organism is limited by the availability of assimilable phosphorus, and said nutrient medium contains said limiting nutrient in a concentration proportional to dilution rate, such that limiting nutrient concentration is increased as dilution rate increases and is decreased as dilution rate decreases; and wherein said process is conducted as a nutrient-limited fermentation and under conditions such that biomass expresses its maximal value for both q s and q p under conditions of nutrient limitation and said process is conducted at a lower biomass concentration and a higher specific rate of ethanol formation than a similar process conducted with a nutrient medium containing phosphorus in excess; and wherein each of said processes is carried out at the same fermentation temperature, dilution rate and concentration of assimilable carbon.
Claim 19
Dependent Claim
33 words
Process according to claim 15 wherein fermentation is conducted at a temperature of about 27° C. to about 37° C. in a fermentation medium having a pH of about 4.5 to about 6.5.
Claim 20
Dependent Claim
14 words
Process according to claim 16 wherein said organism is Z. mobilis strain ATCC 29191.
Claim 21
Dependent Claim
28 words
Process according to claim 16 wherein said substrate is comprised of glucose and the substrate concentration in the fermentation medium is about 100 g/L to about 180 g/L.
Claim 22
Dependent Claim
15 words
Process according to claim 18 wherein effluent from the process is substantially free of substrate.
Claim 23
Dependent Claim
21 words
Process according to claim 18 wherein concentration of ethanol in the fermentation medium is about 50 g/L to about 60 g/L.
Claim 24
Dependent Claim
16 words
Process according to claim 15 wherein said phosphorus is derived from KH 2 PO 4 .
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