Discovery and mechanism of intestinal bacteria in enzymatic cleavage of C-C glycosidic bonds.

C-Glycosides, a special type of glycoside, are frequently distributed in many kinds of medicinal plants, such as puerarin and mangiferin, showing various and significant bioactivities. C-Glycosides are usually characterized by the C-C bond that forms between the anomeric carbon of sugar moieties and the carbon atom of aglycon, which is usually resistant against acidic hydrolysis and enzymatic treatments. Interestingly, C-glycosides could be cleaved by several intestinal bacteria, but whether the enzymatic cleavage of C-C glycosidic bond is reduction or hydrolysis has been controversial; furthermore, whether existence of a "C-glycosidase" directly catalyzing the cleavage is not clear. Here we review research advances about the discovery and mechanism of intestinal bacteria in enzymatic cleavage of C-C glycosidic bond with an emphasis on the identification of enzymes manipulation the deglycosylation. Finally, we give a brief conclusion about the mechanism of C-glycoside deglycosylation and perspectives for future study in this field.

Complete genome sequence of astaxanthin-producing bacterium Altererythrobacter ishigakiensis NBRC 107699.

Altererythrobacter ishigakiensis NBRC 107699 was isolated from marine sediment collected from a site on the coast of Ishigaki Island, Japan and deposited to the NITE Biological Resource Center. This strain is able to produce astaxanthin, which can be used as a food supplement. Here we describe the genome sequence and annotation, as well as the features of the organism. The genome of strain NBRC 107699 comprises 2,673,978bp and contains 2618 protein-coding genes (1966 with predicted functions), 42 tRNA genes and 3 rRNA genes. A. ishigakiensis NBRC 107699T encodes fifteen genes related to astaxanthin production, revealing its potential application in biotechnological industry. The genome sequence of A. ishigakiensis NBRC 107699 now provides the fundamental information for future studies.