Utilization of volatile fatty acids from the anaerobic digestion liquor of sewage sludge for 5-aminolevulinic acid production by photosynthetic bacteria

Abstract

Using volatile fatty acids (VFA) from the anaerobic digestion liquor of sewage sludge, up to 9.2 m m 5-aminolevulinic acid (ALA) could be produced by Rhodobacter sphaeroides under anaerobic-light (5 kLux) conditions with repeated addition of levulinic acid (LA) and glycine and using a large inoculum (approx. 2 g/l of cells, initially from glutamate/malate medium). As the VFA medium also contained organic nitrogen sources such as glutamic acid, the cells were later grown up to about 2 g/l in the VFA medium instead of the glutamate/malate medium. ALA production was then again promoted by adding LA and glycine. Using this improved method, up to 9.3 m m ALA was produced by feeding propionate and acetate together with LA and glycine, indicating that VFA medium formed from sewage sludge could be useful for ALA production. © 1994 Rapid Communications of Oxford Ltd.