Abstract: A method of producing L-amino acids by fermentation. Microorganisms of the genus Corynebacterium which exhibit an auxotrophy relative to an amino acid are used as biocatalysts. The method is characterized in that the carbon source on the one hand and the limiting amino acid on the other hand are fed in two or more different infeed currents to the process. The infeed profiles have, for example, a concave (saccharose) and an exponential (amino acid) form or a convex (saccharose) and likewise a convex (amino acid) form, with specific differing degrees of increase of the currents relative to each other over time.

Abstract: The invention is relates to improved stirred-tank reactors which are suitable, due to special fittings, for converting the results of e.g. microbial or enzymatic processes obtained when they are used on a laboratory scale into an industrial scale. A shaft-driven disk agitator is provided, with at least one perforated disk being attached in the reactor above and/or below the disk agitator.

Abstract: An animal feed supplement and processes for its production which provide an inexpensive, not excessively hygroscopic or sticky supplement amino acid whose content should be standardizable. The animal feed supplement is based on a fermentation broth and contains the predominant proportion of its contents, optionally with the exclusion of part of the biomass. The biomass is preferably present in an amount of at most 10% by weight in the dry state. Proteins are preferably present in a maximum amount of 10% by weight. For the production, the sugar content is adjusted to a maximum of 4 g/l during fermentation, at least towards the end thereof, and at least part of the biomass is optionally removed during the working up.

Abstract: The invention is directed to obtaining phenylalanine-dehydrogenase containing microorganisms by a special selection process comprising obtaining microorganisms, especially strains of Rhodococcus and the phenylalanine-dehydrogenase obtained in them. With the help of this enzyme there are obtained L-.alpha.-aminoacids from the corresponding ketocarboxylic acids by reductive amination.

Abstract: A microbiologically produced, thermostable N-acylproline-acylase and a process for obtaining it from Comamonas testosteroni DSM 5416 and Alcaligenes denitrificans DSM 5417. The enzyme is useful for the synthesis of L-proline from various N-acyl-L-proline derivatives.

Abstract: The invention is directed to a method of producing L-amino acids from .alpha.-ketocarboxylic acids by means of continuous fermentation with the aid of glutamate producing bacteria with biomass retention in which the cells are separated by microfiltration and/or centrifugal separators.

Abstract: A substantially purified N-acyl-L-proline-acylase from Comamonas testosteroni DSM 5416 and Alcaligenes denitrificans DSM 5417. The enzyme is useful for the synthesis of L-proline from various N-acyl-L-proline derivatives.

Abstract: A method for the fermentative production of L-isoleucine from D,L-.alpha.-hydroxybutyrate by means of mutants of the genus Corynbecaterium which utilize D-lactate.

Abstract: The preparation of an L-amino acid, particularly valine, leucine, isoleucine, alanine and phenylalanine, from the corresponding .alpha.-keto carboxylic acid by bacterial fermentation in the presence of ammonium ions is carried out with the aid of thermophilic Bacillus strains at temperatures above 45.degree. C., in particular above 60.degree. C. Bacillus strains DSM 406, 452, 461, 42, 463, 465 and 466 are particularly suitable for this purpose. The greater solubility of the amino acid at the elevated fermentation temperature permits the separation out of the amino acid from the reaction mixture simply by cooling, whereafter the depleted reaction mixture can be pumped back into the fermenter. Especially favorable yields are achieved by supplying oxygen to the fermenter to an amount of less than about 20% dissolved oxygen.

Abstract: A microbiologically produced .alpha.-acetylamino cinnamic acid acylase and a method for its production from Brevibacterium species NCIB 12246 or NCIB 12247. The new enzyme can be used as constituent of a coupled enzyme system for enzymatic conversions which run via the intermediary stage .alpha.-imino-.beta.-phenylpropionic acid or phenylpyruvic acid.

Abstract: L-amino acids present in cleavage solutions obtained in the acylase-catalyzed cleavage of N-acetyl-D,L-amino acids are isolated by use of a strongly acidic ion exchanger in H+ form. First, the mother liquor from a previous treatment cycle is fed to the ion exchanger, and then the cleavage solution and finally the wash water and the discharge from the ion exchanger which is pH-controlled is analyzed into an "effluent water fraction", an "N-acetyl-D-amino acid fraction" and an "L-amino acid fraction". The last fraction is adjusted by addition of fresh cleavage solution to a pH of between 4.0 and 6.0, and from the mixture which is thus obtained the L-amino acid is isolated by crystallization. The mother liquor which is obtained is recycled back into a subsequent treatment cycle.

Abstract: The subject matter of the invention is a new D(-)-mandelate-dehydrogenase and obtaining it from Lactobacillus curvatus DSM 20019 (obtainable from the German Collection of Microorganisms). The new enzyme can be used for the enzymatic conversion of D(-)-mandelic acid and various other D-2-hydroxycarboxylic acids into the corresponding 2-ketocarboxylic acids or from benzoyl formate and various other 2-ketocarboxylic acids conversion to the corresponding D-2-hydroxycarboxylic acids.

Abstract: .alpha.-Hydroxycarboxylic acids are continuously converted into the corresponding optically active .alpha.- aminocarboxylic acids. The conversion is carried out in a membrane reactor in the presence of nicotinamide-adenine dinucleotide increased in molecular weight by bonding to a water soluble high molecular weight material, a dehydrogenase specific for the .alpha.-hydroxycarboxylic acid, a dehydrogenase specific for the corresponding .alpha.-amino-carboxylic acid and ammonium ions. There is continuously supplied to the membrane reactor an aqueous solution of the .alpha.-hydroxycarboxylic acid to be reacted, a substantially lesser amount of the corresponding .alpha.-ketocarboxy lic acid, and an amount of ammonium ion at least equivalent to the .alpha.-hydroxycarboxylic acid to be reacted. There is maintained over the membrane a difference in pressure 1 and 15 bar. Behind the membrane, there is continuously drawn off a filtrate stream containing the .alpha.-aminocarboxylic acid formed.

Abstract: The reaction mixture obtained in the enzymatic reaction of fumaric acid to form L-malic acid contains the L-malic acid and unreacted fumaric acid as their salts. To recover pure solutions of L-malic acid the reaction mixture is treated at 50.degree. to 150.degree. C. with cation exchangers. The eluate after concentration to 30 to 80 weight % content of L-malic acid is filtered. The pure L-malic acid is recovered by evaporating the solutions, in a given case after treatment with activated carbon.

Abstract: The enzyme D-2-hydroxy-4-methylpentanoic acid dehydrogenase has been prepared by culturing readily available Lactobacillus or Leuconostoc, microorganisms, such as Lactobacillus casei ssp. pseudoplantarum and Leuconostoc mesenteroides. The microbiologically produced enzyme has special characteristics and is capable of converting D-2-hydroxycarboxylic acids, such as D-2-hydroxy-4-methylpentanoic acid to the corresponding 2-ketocarboxylic acid and is capable of enzymatically converting 2-ketocarboxylic acids, such as 2-keto-4-methylpentanoic acid and 2-ketobutyric acid to the corresponding D-2-hydroxycarboxylic acid.

Abstract: The invention is directed to a microbiologically produced L-phenylalanine-dehydrogenase and a process for its recovery from Brevibacterium species DSM 2448. The new enzyme can be used for the enzymatic conversion of phenyl pyruvic acid, p-hydroxyphenyl pyruvic aid, indolyl pyruvic acid or 2-keto-4-(methylmercapto)-butyric acid into the corresponding L-.alpha.-aminocarboxylic acids.

Abstract: The purpose of the invention is the new enzyme L-2-hydroxy-4-methylpentanoic acid-dehydrogenase and its recovery from Lactobacillus confuses. The new enzyme can be used to enzymatically change L-2-hydroxy-4-methylpentanoic acid and various other L-2-hydroxy-carboxylic acids into the corresponding 2-ketocarboxylic acids or 2-keto-4-methylpentanoic acid and various other 2-ketocarboxylic acids into the corresponding L-2-hydroxycarboxylic acids.

Abstract: 1-Methyl-2-chlorocyclopropanecarboxylic acid and its lower esters are produced by the selective hydrogenating dechlorination of the corresponding 1-methyl-2,2-dichlorocyclopropane compounds. The new materials can be used as intermediate products for the production of pesticides and medicines.

Abstract: Water soluble .alpha.-ketocarboxylic acids are continuously converted in a membrane reactor into the corresponding .alpha.-hydrocarboxylic acids. The conversion takes place in the presence of a substrate specific dehydrogenase and of a nicotinamide-adenine-dinucleotide (NAD.sup.+ /NADH) enlarged in molecular weight through linkage to a water soluble polymer as coenzyme. Simultaneously NADH is regenerated continuously from NAD.sup.+ in presence of a formate dehydrogenase and from formate ion. The membrane must have a mean pore diameter of 1 to 3 nm. As coenzyme there is employed 0.1 to 10 mmol/l of NAD.sup.+ /NADH present bound to a water soluble polymer having an average molecular weight between 500 and 50,000. There is continuously supplied to the reactor a substrate stream which contains 50 to 100% of the maximum amount soluble, but not over 2,000 mmol/l, of the reacting .alpha.-ketocarboxylic acid in the form of a water soluble salt and 100 to 6,000 mmol/l of a formate.

Abstract: 3-Cyanopropionamide is produced by adding hydrocyanic acid on acrylamide in the presence of an aprotic organic solvent and an alkali metal cyanide at a temperature between 20.degree. and 150.degree. C. 3-cyanopropionamide is an important intermediate product for the production of pyrrolidone or 4-aminobutyramide.