Abstract: Fumaric acid is produced by reacting a culture of a microorganism which produces maleate isomerase that exhibits a maximum activity at not less than 50.degree. C. or a treated product thereof with maleic acid in an aqueous solution, and isomerizing maleic acid to produce fumaric acid. L-aspartic acid is produced by reacting both of a culture of a microorganism which produces maleate isomerase or a treated product thereof and a culture of a microorganism which produces aspartase or a treated product thereof with maleic acid and ammonia in an aqueous solution, producing L-aspartic acid from maleic acid and ammonia by enzyme reactions, and recovering L-aspartic acid from the reaction mixture.

Abstract: The present invention relates to a process for producing L-tryptophan in a single-stage reaction, comprising carrying out an L-tryptophan producing reaction with glycine, formaldehyde and indole as raw materials in an aqueous solution in the presence of microbial cells having serine transhydroxymethylase or a treated products thereof and microbial cells having tryptophan synthase or tryptophanase, or a treated products thereof; and collecting produced L-tryptophan from the reaction solution.

Abstract: An oligonucleotide comprising a specific region and one or two non-specific regions which are bound to at least one of the two termini of the specific region, wherein the specific region has a specific base sequence which is substantially complementary to a target sequence of a sample nucleic acid with which the oligonucleotide is to be hybridized, the non-specific region is composed of at least one nucleotide having other base capable of forming a base pair with each of bases constituting a common nucleic acid, or its oligomer, is used as a probe for the hybridization.

Abstract: Fumaric acid is produced by reacting maleic acid in an aqueous solution with a microorganism which has maleate isomerase activity or with a preparation from the microorganism having the maleate isomerase activity, and producing fumaric acid in a reaction solution by enzymatic isomerization of maleic acid carried out under the condition that the dissolved oxygen concentration in the reaction solution is substantially maintained at 4 ppm or less, for example, by sealing the reaction solution with one or more gases selected from N.sub.2, Ar, and He.

Abstract: There is disclosed a process for preparing indigo which comprises bringing an indigo-producing bacteria belonging to genus Acinetobacter or treated products thereof into contact with an aqueous solution containing at least indole to have indigo formed and accumulated in the aqueous solution; and collecting indigo from the aqueous solution.

Abstract: A process for cultivating a microorganism transformed with a recombinant plasmid at least containing (a) a DNA fragment containing a promoter and a regulator gene tnaC located downstream of the promoter in a tryptophanase operon (tna), and (b) a DNA fragment containing a desired structural gene which can be expressed by the promoter, which comprises cultivating the transformed microorganism in a culture medium while adding glucose as a carbon source continuously or intermittently so that the concentration of glucose is maintained within the range of 0.01 to 0.3%, and thereby allowing the desired structural gene to be expressed in the microorganism.

Abstract: A method of selectively inhibiting pyruvic acid decomposition activity in microorganism cells containing tryptophanase or a treated product thereof, which comprises heat-treating said cells or the treated product thereof in the presence of an ammonium ion.

Abstract: A method for producing L-threonine, which comprises subjecting at least L- or DL-aspartic acid or a salt thereof to enzymatic reaction according to the reaction system not accompanied with growth of microorganism cells in an aqueous solution in the presence of a microorganism and collecting L-threonine formed, wherein the microorganism is a biotin-requiring microorganism for the growth belonging to coryneform bacterium; a plasmid comprising a DNA fragment containing at least a gene encoding biosynthesis of threonine which can be expressed within a biotin-requiring microorganism cell for the growth belonging to coryneform bacterium and a DNA fragment containing a gene encoding autonomous replication within coryneform bacterium cell; and a biotin-requiring microorganism for the growth belonging to coryneform bacterium which has been transformed with the plasmid described above, both of which are employed in the present method.

Abstract: Microorganisms of the genus Pseudomonas containing aspartate beta-decarboxylase at a high level are produced by culturing said microorganism in a medium supplemented with a chelating agent. L-Alanine can be efficiently produced from L-aspartic acid said microorganisms or the treated product thereof.

Abstract: There is disclosed a process for producing L-alanine by reacting in a single reaction tank, in an aqueous reaction mixture having a pH of 6 to 10 and containing at least one .alpha.-keto acid, fumaric acid or a salt thereof with ammonia or ammonium ions in the presence of two microorganisms having fumarase inactivity.

Abstract: A method for producting L-threonine is described, comprising subjecting L- or DL-homoserine to enzymatic reaction in an aqueous medium in the presence of cells of biotin-requiring microorganisms belonging to the genus Brevibacterium and harvesting L-threonine from the reaction mixture.

Abstract: An aqueous solution containing fumaric acid is reacted in the presence of an aerobically cultured product of a microorganism belonging to the Brevibacterium genus and having resistance to .alpha.-aminobutyric acid, whereby L-malic acid is produced.