Abstract: A process for producing L-tryptophan in which a suitable substrate such as a carbohydrate, indole or anthranilic acid is contacted with Coryneform bacteria, where the Coryneform bacteria bear recombinant DNA constructed by connecting a gene coding for tryptophan synthetase with a plasmid vector capable of proliferating in Coryneform bacteria.

Abstract: A novel method of selecting Streptomyces recombinant DNA-containing host cells and vectors useful in exemplifying the method are described. The vectors confer apramycin resistance to sensitive Streptomyces host cells and thus provide a convenient method of selecting Streptomyces transformants. The apramycin resistance-conferring gene used in the method is an acetyltransferase aac(3)IV gene and can be isolated from E. coli K12 BE1041/pKC309 (NRRL B-15827) on an .about.1.5 kb PstI-EcoRI restriction fragment.

Abstract: The isomerase activity of a dry isomerase preparation (e.g., glucose isomerase) is enhanced by initially pretreating the isomerase in an aqueous solution which contains an activating amount of a metal ion activator and/or a thiol generating reducing agent and/or a monosaccharide which the isomerase is capable of isomerizing. Pretreatment temperature and time periods are most suitably conducted in such a manner so as to minimize isomerase deactivation. The pretreatment increases total isomerase activity and thereby renders it more effective for use in an isomerization process (e.g., glucose isomerization).

Abstract: This invention has made it possible to uniformly gelatinize and disperse a highly concentrated starch slurry of a concentration as high as 10% or more by gelatinizing at an elevated temperature; hitherto it was considered next to impossible to uniformly gelatinize and disperse such highly concentrated starch slurries, and, according to the present invention, the upper limit of saccharification of the starch slurry is increased by selectively decomposing the .alpha.-1,6-glucoside bonds in the starch by means of an .alpha.-1,6-glucosidase and, thereby, to make it possible to obtain a highly pure maltose.

Abstract: The present invention is directed to a method for enzymatically isomerizing glucose in glucose-containing liquors. The presence of relatively small amounts of water-soluble salts of sulfurous acids during the enzymatic isomerization of glucose in glucose-containing liquors reduces color formation therein and increases the stability of the glucose-isomerizing enzyme.