4-keto-D-aldopentoses and 4-pentulosonates, new products with Acetic Acid Bacteria

ADACHI, O.; HOURS, R.A.; SHINAGAWA, E.; AKAKABE, Y.; YAKUSHI, T.; MATSUCHITA, K.

Córdoba, Spain

Conferencia; 3rd International Conference on Acetic Acid Bacteria, Vinegar and other products (AAB 2012); 2012

University of Cordoba and Acetic Acid Bacteria Research Network

S4-O-01 4-Keto-D-aldopentoses and 4-Pentulosonates, New Products with Acetic Acid Bacteria   O. Adachi,1* R.A. Hours,2 E. Shinagawa,3 Y. Akakabe,1 T. Yakushi,1 K. Matsushita1   1Dept. Biol. Chem., Fac. Agriculture, Yamaguchi University, Yamaguchi 753-8515, Japan; 2CINDEFI (CONICET, UNLP). School of Science, La Plata National University, Argentina; 3Dept. Chem. Biol. Eng., Ube Natl. Coll. Technol., Ube 755-8555, Japan.   *Corresponding author: osao@yamaguchi-u.ac.jp Phone: +81-83-933-5857     4-Keto-D-aldopentoses and 4-pentulosonates (4-keto-D-pentonates) have been identified for the first time. These are entirely new sugars and sugar acids involving a ketone group at the C4 position in their molecules, while keto-pentoses so far known are limited to those having a ketone group at the C2 position, such as D-, L-ribulose and D-, L-xylulose. A novel strain, Gluconacetobacter liquefaciens RCTMR 10, was isolated from a water-kefir, traditional fermented healthy drink in Argentina. The strain rapidly converted 2,5-diketo-D-gluconate (25DKA) to a new compound with high yield, which was identified to be 4-keto-D-arabonate (4KAB). It appeared that decarboxylation and dehydrogenation reactions took place at a time in the reaction. Finally, 4-keto-D-arabinose (4KAR) was confirmed as the direct precursor of 4KAB and that two novel membrane-bound enzymes, 25DKA decarboxylase and 4-keto-D-aldopentose 1-dehydrogenase, were involved in the reaction. Alternatively, D-arabonate was oxidized to 4KAB with another membrane-bound enzyme, D-pentonate 4-dehydrogenase. Extensive studies have revealed that such a novel sugars and sugar acids can be produced ubiquitously by oxidative fermentation with most strains of Gluconobacter and Gluconacetobacter. 4KAR and 4KAB were produced from D-glucose via 25DKA and also from D-arabinose. Likewise, D-ribose was oxidized to 4-keto-D-ribose and it was oxidized further to 4-keto-D-ribonate. In D-aldopentose oxidation, D-aldopentose 4-dehydrogenase has been confirmed in the membrane fraction of acetic acid bacteria. In this study, four different novel compounds and four different new membrane-bound enzymes have been identified. Among the membrane-bound enzymes characterized, D-aldopentose 4-dehydrogenase has been confirmed as a new quinoprotein, PQQ-dependent enzyme.   Keywords: D-aldopentose 4-dehydrogenase; 4-keto-D-aldopentose 1-dehydrogenase; 2,5-diketo-D-gluconate decarboxylase; 4-keto-D-aldopentose; 4-keto-D-pentonate