Photorhabdus luminescens, a bacterial symbiont of entomopathogenic biocontrol nematodes, was grown in batch and glucose fed-batch culture. The cell density, bioluminescence, production of antibiotic substances, number of cells with inclusion bodies, glucose concentration and oxygen uptake rate were recorded. The addition of 12.4 g l(-1) glucose prolonged the growth, and the yield almost doubled, from 6.85 g l(-1) to 12.45 g l(-1) dry mass. The production of antibiotic substances increased by 140%. Bioluminescence was higher in the batch culture. A shift of P. luminescens to phase II variants was not detected.