New Functions and Potential Applications of Amino Acids.

Currently, several types of amino acids are being produced and used worldwide. Nevertheless, several new functions of amino acids have been recently discovered that could result in other applications. For example, oral stimulation by glutamate triggers the cephalic phase response to prepare for food digestion.

Present Global Situation of Amino Acids in Industry.

At present, amino acids are widely produced and utilized industrially. Initially, monosodium glutamate (MSG) was produced by extraction from a gluten hydrolysate. The amino acid industry started using the residual of the lysate.

Effective cellulose production by a coculture of Gluconacetobacter xylinus and Lactobacillus mali.

A microbial colony that contained a marked amount of cellulose was isolated from vineyard soil. The colony was formed by the associated growth of two bacterial strains: a cellulose-producing acetic acid bacterium (st-60-12) and a lactic acid bacterium (st-20). The 16S rDNA-based taxonomy indicated that st-60-12 belonged to Gluconacetobacter xylinus and st-20 was closely related to Lactobacillus mali.

Coenzyme specificity of enzymes in the oxidative pentose phosphate pathway of Gluconobacter oxydans.

The coenzyme specificity of enzymes in the oxidative pentose phosphate pathway of Gluconobacter oxydans was investigated. By investigation of the activities of glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) in the soluble fraction of G. oxydans, and cloning and expression of genes in Escherichia coli, it was found that both G6PDH and 6PGDH have NAD/NADP dual coenzyme specificities.

Transaldolase/glucose-6-phosphate isomerase bifunctional enzyme and ribulokinase as factors to increase xylitol production from D-arabitol in Gluconobacter oxydans.

Xylitol production from D-arabitol by the membrane and soluble fractions of Gluconobacter oxydans was investigated. Two proteins in the soluble fraction were found to have the ability to increase xylitol production. Both of these xylitol-increasing factors were purified, and on the basis of their NH(2)-terminal amino acid sequences the genes encoding both of the factors were cloned.

Cloning of the xylitol dehydrogenase gene from Gluconobacter oxydans and improved production of xylitol from D-arabitol.

Xylitol dehydrogenase (XDH) was purified from the cytoplasmic fraction of Gluconobacter oxydans ATCC 621. The purified enzyme reduced D-xylulose to xylitol in the presence of NADH with an optimum pH of around 5.0.

Construction of a vector plasmid for use in Gluconobacter oxydans.

A host vector system in Gluconobacter oxydans was constructed. An Acetobacter-Escherichia coli shuttle vector was introduced with the efficiency of 10(4) transformants/microg of DNA. Next, aiming for a self-cloning vector, we found a cryptic plasmid (which we named pAG5) of 5648 bp in G.