Isolation and characterization of an Achromobacter xylosoxidans strain B3 and other bacteria capable to degrade the synthetic chelating agent iminodisuccinate.

Three bacterial strains were isolated, which used the synthetic chelating agent iminodisuccinate (IDS) as sole carbon source for growth in mineral salts media (MSM). Taxonomic analysis and 16S rDNA sequence analysis identified one of these isolates (B3), which was isolated from sewage sludge, as a strain of Achromobacter xylosoxidans subsp. xylosoxidans. It exhibited a doubling time of approximately 3 h in liquid MSM supplemented with IDS and grew even in the presence of 1.0% (w/v) IDS. Since photometric and high performance liquid chromatography analysis showed that IDS, which came onto the market only recently as an alternative for ethylenediaminetetraacetate, was completely degraded by axenic cultures of bacteria; it will probably be readily degraded in the environment.

Tocopherol synthesis from homogentisate in Capsicum anuum L. (yellow pepper) chromoplast membranes: evidence for tocopherol cyclase.

The present study shows for the first time appreciable tocopherol cyclase activities in plastidial membrane preparations of Capsicum annuum L. (yellow pepper) fruits. When chromoplast membranes from yellow peppers were incubated with [3H]homogentisate and phytyl pyrophosphate under strictly reducing conditions, all biosynthesis precursors were labelled. The main labelling was found in gamma-tocopherol. These observations contradict the hypothesis that assigns a rate-limiting function to tocopherol cyclase in plastidial alpha-tocopherol biosynthesis. The stoichiometry of alpha-tocopherol, 2,3-dimethylphytylquinol and gamma-tocopherol formation and the inhibition of alpha-tocopherol synthesis by increasing gamma-tocopherol concentrations suggests the regulation of this pathway by its precursors.