Biosynthesis of flexirubin: Incorporation of precursors by the bacterium Flexibacter elegans

Biosynthesis of flexirubin (1) by Flexibacter elegans (Cytophagaceae) is closely linked to growth. Out of a number of experimental conditions tested, only lowering of the pH of the medium to slightly acid conditions led to a reduced specific pigment content. The latter returned very slowly to normal when the pH was increased again. Under no conditions was a stimulation of pigment synthesis observed. The following ¹⁴C-labelled compounds were incorporated into flexirubin with sufficiently high efficiency to accept them as precursors: acetate, malonate, tyrosine and methionine.     

Complete genome sequence of Leadbetterella byssophila type strain (4M15)

Leadbetterella byssophila Weon et al. 2005 is the type species of the genus Leadbetterella of the family Cytophagaceae in the phylum Bacteroidetes. Members of the phylum Bacteroidetes are widely distributed in nature, especially in aquatic environments. They are of special interest for their ability to degrade complex biopolymers. L. byssophila occupies a rather isolated position in the tree of life and is characterized by its ability to hydrolyze starch and gelatine, but not agar, cellulose or chitin. Here we describe the features of this organism, together with the complete genome sequence, and annotation. L. byssophila is already the 16(th) member of the family Cytophagaceae whose genome has been sequenced. The 4,059,653 bp long single replicon genome with its 3,613 protein-coding and 53 RNA genes is part of the Genomic Encyclopedia of Bacteria and Archaea project.     

Untersuchungen zur biogenese des flexirubins—herkunft des benzolringes a und der aromatischen C-methylgruppen

In radioactive flexirubins formed in culture from different radioactive precursors, the labelling was located by chemical degradation. The results show unambiguously that only the methyl group of ring A originates from methionine. The benzene ring A is derived from tyrosine, which is incorporated as a C₆-C₃ unit. Acetate acts as the main precursor of the polyene and participates in the biosynthesis of ring B.