Chemistry: molecular biology and microbiology – Micro-organism – tissue cell culture or enzyme using process... – Preparing oxygen-containing organic compound
Reexamination Certificate
2001-06-19
2003-12-09
Raymond, Richard L. (Department: 1624)
Chemistry: molecular biology and microbiology
Micro-organism, tissue cell culture or enzyme using process...
Preparing oxygen-containing organic compound
C554S175000, C554S206000, C554S207000, C562S494000, C562S580000, C562S590000, C562S597000, C562S600000, C562S606000
Reexamination Certificate
active
06660505
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a process for recovering a carboxylic acid made by the biological oxidation of a substrate by a microorganism from an aqueous media such as a fermentation broth.
2. Description of Related Art
Standard methods for recovering carboxylic acids in general and polycarboxylic acids in particular from fermentation broths are typically based on the physical separation of the spent microorganism cells from the aqueous phase such as by centrifugation followed by precipitation of the carboxylic acid as a result of pH reduction of the aqueous phase. This method is unsatisfactory for a number of reasons, the most notable of which includes the problem of physically separating the spent cells and then acidifying the cell-free broth to effect the precipitation of the carboxylic acid. The precipitation of the carboxylic acid is time consuming and the separation and isolation of the precipitated carboxylic acid is not always clean, i.e., there can be impurities which adversely affect the quality and purity of the final product.
Accordingly, there is a continuing need for improved processes for recovering carboxylic acids from a fermentation broth.
SUMMARY OF THE INVENTION
The present invention involves an improved process for the recovery of a carboxylic acid made by the biological oxidation of a substrate by a microorganism such as a yeast. Carboxylic acids are recovered from a fermentation broth by extracting the broth with a solvent containing one or more olefins without the need for first removing the spent microorganism cells. In one aspect, a cosolvent is combined with one or more olefins to create a solvent which favorably adjusts the partition coefficient. A preferred solvent for the extraction of carboxylic acids from a fermentation broth contains a mixture of tertiary-butyl acetate and diisobutylene.
In another aspect, a method for isolating at least one carboxylic acid from an aqueous mixture is provided which includes providing an aqueous mixture containing at least one carboxylic acid, contacting a solvent containing at least one olefin with the aqueous mixture, allowing the at least one carboxylic acid to separate into a solvent and isolating the solvent containing the at least one carboxylic acid from the aqueous mixture. A co-solvent may be combined with the at least one olefin.
Solvents are provided, which in one embodiment, include a mixture of a minority amount of tertiary butyl acetate and a majority amount of diisobutylene. During the process of recovering the carboxylic acids, one or more co-solvents may be included which generally aid in the process, e.g., by reducing the amount of solvent needed to remove the carboxylic acids, and/or the number of extraction cycles necessary to adequately remove the carboxylic acids from the fermentation broth.
After employing a fermentation procedure to produce a carboxylic acid, the viscosity of the fermentation broth may optionally be adjusted, preferably by heating the fermentation broth, to form a flowable liquid. The pH of a fermentation broth which contains one or more carboxylic acids may be optionally adjusted to a value of from at least about 1.5 to about 7.0. The carboxylic acid containing broth is contacted with a solvent containing one or more olefins to extract the carboxylic acid. The carboxylic acid may then be isolated by separating crystals of the carboxylic acid from the extraction solvent.
DETAILED DESCRIPTION OF THE INVENTION
Except in the claims and the operating examples, or where otherwise expressly indicated, all numerical quantities in this description indicating amounts of material or conditions of reaction and/or use are to be understood as modified by the word “about” in describing the broadest scope of the invention. Practice within the numerical limits stated is generally preferred. Also, throughout this description, unless expressly stated to the contrary: percent, “parts” of, and ratio values are by weight; the description of a group or class of materials as suitable or preferred for a given purpose in connection with the invention implies that mixtures of any two or more of the members of the group or class are equally suitable or preferred; description of constituents in chemical terms refers to the constituents at the time of addition to any combination specified in the description or of generation in situ by chemical reactions specified in the description, and does not necessarily preclude other chemical interactions among the constituents of a mixture once mixed; and the term “mole” and its grammatical variations may be applied to elemental, ionic, and any other chemical species defined by number and type of atoms present, as well as to compounds with well defined molecules.
It is understood that a carboxylic acid is any compound containing one or more carboxyl groups. A polycarboxylic acid is any compound having two or more carboxyl groups.
A flowable liquid is a fluid whose molecules are free to move past one another while remaining in sliding contact.
The process for the recovery of a carboxylic acid according to the invention was based on fermenting a microorganism in a culture medium which is comprised of a nitrogen source, and at least an organic substrate and then recovering the carboxylic acid by contacting the broth with a suitable extractant. The organic substrate can be any compound which can be oxidized to a compound having at least one carboxyl group by biooxidation. For the production of carboxylic acids, the substrate can be any compound having at least one methyl group, a terminal carboxyl group and/or a terminal functional group which is oxidizable to a carboxyl group by biooxidation. The substrate can also contain one or more carbon—carbon multiple bonds and/or one or more carboxylic or heterocyclic aromatic rings. The microorganism can be any microorganism that is capable of biologically oxidizing an organic substrate as set forth above to a compound having at least one carboxyl group.
The process for the recovery of a carboxylic acid is applicable to the production by fermentation of any carboxylic acid that has between 3 and 36 carbon atoms, preferably 5 to 36 atoms and more preferably 9 to 36 carbon atoms. The process for the recovery of a carboxylic acid is particularly applicable to the production of polycarboxylic acids by fermentation and most particularly to the production of dicarboxylic acids. Examples of such dicarboxylic acids include, but are not limited to, oxalic acid, maleic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, phthalic acid, azelaic acid, sebacic acid, dodecanedioic acid, brassylic acid, 9-octadecenedioic acid, C-36 dimer acid and isomers thereof. The process is also applicable to the recovery of monobasic carboxylic acids which can be saturated, unsaturated or polyunsaturated. Examples of such monocarboxylic acids include, but are not limited to: caprylic, pelargonic, capric, undecylic, lauric, myristic, pentadecanoic, palmitic, heptadecanoic, stearic, arachidic, palmitoleic, oleic, erucic, linoleic, and linolenic and isomers thereof.
The microorganisms can be any microorganism capable of biooxidizing the substrate as defined herein. Typically, such a microorganism will be a yeast. Several strains of yeast are known to excrete alpha, omega-dicarboxylic acids as a byproduct when cultured on alkanes or fatty acids as the carbon source. Certain strains are set forth, e.g., in U.S. Pat. No. 5,254,466 and PCT/US99/20797, the entire contents of which are each incorporated herein by reference. Preferably, the microorganism is a beta-oxidation blocked
C. tropicalis
cell which has been genetically modified so that the chromosomal POX4A, POX4B and both POX5 genes have been disrupted. The substrate flow in this strain is redirected to the omega-oxidation pathway as the result of functional inactivation of the competing &bgr;-oxidation pathway by POX gene disruption. The strain may also have one or more reductase genes amplified which results in an increase in the amou
Cognis Corporation
Drach John E.
Raymond Richard L.
Trzaska Steven J.
Tucker Zachary C.
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