A glucose-limited chemostat was used to determine the growth parameters of BBK006 for continuous production of the biosurfactant surfactin. The continuous cultivation exhibited low maintenance metabolism (m = 0.39 mmol(gluose) g(bacteria)(-1) h(-1)) and high molar growth yield (17,s' = 30.8 g(bacteria) mol(glucose)(-1)). It was found that the surfactin production rate in continuous culture was not only a function of dilution rate but also varied with the initial concentration of glucose in the feed. A high steady state concentration of surfactin (18 mg L-1) was maintained in the culture at a dilution rate of 0.2 h(-1) when glucose concentration in the feed was 0.25 g L-1. This is the first demonstration of continuous surfactin production and recovery using glucose as a carbon source. The production of surfactin is known to be related to the age of the microorganisms and a simple mathematical model has been constructed to show how the age-related production can be quantified. (c) 2006 Society of Chemical Industry