DETERMINATION OF THE KINETIC-PARAMETERS DURING CONTINUOUS CULTIVATIONOF THE LIPASE PRODUCING THERMOPHILE BACILLUS SP IHI-91 ON OLIVE OIL

A thermostable lipase was produced in continuous cultivation of a newl y isolated thermophilic Bacillus sp. strain IHI-91 growing optimally a t 65 degrees C. Lipase activity decreased with increasing dilution rat e while lipase productivity showed a maximum of 340 U l(-1) h(-1) at a dilution rate of 0.4 h(-1). Lipase productivity was increased by 50% compared to data from batch fermentations. Up to 70% of the total lipa se activity measured was associated to cells and by-products or residu al substrate. Kinetic and stoichiometric parameters for the utilisatio n of olive oil were determined. The maximal biomass output method led to a saturation constant K-s of 0.88 g/l. Both batch growth data and a washout experiment yielded a maximal specific growth rate, mu(max), o f 1.0 h(-1). Oxygen uptake rates of up to 2.9 gl(-1)h(-1) were calcula ted and the yield coefficient, Y-X/O, was determined to be 0.29 g dry cell weight/g O-2. From an overall material balance the yield coeffici ent. Y-X/S,Y- was estimated to be 0.60 g dry cell weight/g olive oil.