Chemistry: molecular biology and microbiology – Micro-organism – tissue cell culture or enzyme using process... – Preparing alpha or beta amino acid or substituted amino acid...
Patent
1999-10-18
2000-06-06
Lilling, Herbert J.
Chemistry: molecular biology and microbiology
Micro-organism, tissue cell culture or enzyme using process...
Preparing alpha or beta amino acid or substituted amino acid...
562554, 562571, C12P 1320, C07C22700, C07C22900
Patent
active
060717289
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for the production of crystalline aspartic acid.
Aspartic acid is an acidic amino acid with a molecular formula of HOOCCH.sub.2 CH(NH.sub.3)COO. It is used in products such as the aspartame sweetener and for formation of the biodegradable polymer polyaspartic acid (PAA). The latter could be utilized as a cobuilder or as a sequestrant in detergents, as a super absorbent polymer and in other applications. The biodegradability of PAA is very attractive, and the potential market is large. It strongly depends, however, on the availability of a low cost aspartic acid and a non-contaminating process for the preparation of aspartic acid.
Aspartic acid is usually produced by enzymatic conversion of diammonium fumarate, as disclosed, e.g., in U.S. Pat. No. 3,198,712, corresponding to British Patent 1,004,218, in which there is described and claimed a process for producing L-aspartic acid which comprises mixing Pseudomonas trifolii with an aqueous solution containing a fumaric compound selected from the group consisting of fumaric acid and fumarate and an ammonia compound selected from the group consisting of ammonia and ammonium salt, maintaining the resulting mixture at approximately neutral condition whereby L-aspartic acid forms, and recovering L-aspartic acid from said admixture. The diammonium fumarate is usually a product of reacting ammonia and fumaric acid. The latter is a product of converting maleic acid, which, in turn, is a petrochemical product.
U.S. Pat. No. 3,391,059 describes a process wherein microorganisms capable of converting ammonium maleate directly into aspartic acid (or its salt), are isolated. U.S. Pat. No. 4,013,508 describes a process utilizing two different microorganisms. One converts hydrocarbons to fumaric acid, which is then converted by the other to aspartic acid.
The ammonium aspartate formed contains various impurities that could result from the enzyme, the nutrients used, products of said reactions, etc. Currently, it is purified by acidulation through the addition of a stoichiometric amount of a mineral acid, e.g. sulfuric acid, to reach a pH in the range of about the isoelectric point of the aspartic acid. The aspartate ion is converted to aspartic acid in zwitterionic form, which precipitates out of the solution. This solution contains ammonium sulfate as the main component. The presence of the sulfate salt decreases the purity of the precipitating product due to coprecipitation of contaminants, which coprecipitation is induced by the high ionic strength. It also increases the solubility of aspartic acid in the solution, which reduces the yields. Another disadvantage of the process is the consumption of ammonia and sulfuric acid and the formation of a salt that can be used only as a low grade fertilizer (in most cases at the added cost of the energy and equipment needed to crystallize it out of the solution).
U.S. Pat. No. 4,560,653, assigned to W. R. Grace, and WO 9617950 assigned to Mitsubitshi claims a process for preparing L-aspartic acid, wherein a substrate containing fumarate ions is reacted in the presence of an aspartase, the improvement comprising reducing the pH of the aqueous solution resulting from the contact with said aspartase or aspartase-producing microorganism to about 3 to 4 by addition of maleic anhydride, maleic acid or salts thereof, to insolubilize L-aspartic acid while providing maleic acid in the supernatant phase, removing the insoluble L-aspartic acid, isomerization of the maleic acid in the supernatant phase to fumaric acid, adjusting the pH of the supernatant phase to about 8 to 9, and passing the supernatant phase into contact with aspartase or aspartase-producing microoganism.
A further improvement to this idea is suggested in U.S. Pat. No. 5,541,090. The ammonium maleate formed in the acidulation of the ammonium aspartate solution is directly bioconverted to ammonium aspartate. Thus, said patent describes and claims a process for production of L-aspartic acid comprising the steps of (1) contacting (A) a
REFERENCES:
patent: 5488155 (1996-01-01), Brun et al.
patent: 5530160 (1996-06-01), Nore et al.
patent: 5541090 (1996-07-01), Sakano et al.
Asher Vitner
Cami Pierre
Chattaway Thomas
Eyal Aharon M.
Jansen Robert
A. E. Staley Manufacturing Co.
Amylum Belgium N.V.
Lilling Herbert J.
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