Ripromycin and other polycyclic macrolactams from Streptomyces sp. Tü 6239: taxonomy, fermentation, isolation and biological properties.

Strain Tü 6239 was isolated from a soil sample collected in Brazil and determined as a new species of the genus Streptomyces. In the course of our HPLC-diode array screening program three metabolites were detected in the culture filtrate and mycelium extracts of strain Tü 6239. They were characterised as members of the macrolactam group, the new compound ripromycin (1), the previously described ikarugamycin (2) and a new derivative of it, ikarugamycin epoxide (3).

Bagremycin A and B, novel antibiotics from streptomyces sp. Tü 4128.

Two novel secondary metabolites, bagremycin A (2) and B (3), were detected in the culture filtrate of Streptomyces sp. Tü 4128 by HPLC-diode-array screening. They are phenol esters of 3-amino-4-hydroxybenzoic acid with a derivative of p-coumaric acid and show a moderate activity against gram-positive bacteria and some fungi.

Bioconversion of glucose and fructose to sorbitol and gluconic acid by untreated cells of Zymomonas mobilis.

The bioconversion of glucose and fructose to gluconic acid and sorbitol, respectively, by the enzymes glucose-fructose oxidoreductase (GFOR) and glucono-delta-lactonase (GL), contained in untreated cells of Zymomonas mobilis ATCC 29191, was investigated in batch runs with glucose plus fructose concentrations (S0) varying from 100 to 750 g l-1 in equimolar ratio. When S0 was increased to 650 g l-1, the yields were improved, reaching a maximum of 91% for both products, with productivities of 1.6 and 1.