Effects of mass transfer and reaction kinetics on serum cholesterol depletion rates of free and immobilized Pseudomonas pictorum.

Pseudomonas pictorum in free or immobilized form can deplete serum cholesterol. The reaction kinetics control the global rate of cholesterol depletion during the initial part of free P. pictorum fermentation. Then, mass transfer takes control of the global rate. In this part of the fermentation, the global rate is first order with respect to the cholesterol concentration. The halftime was 330 min. The global rate is zero order with respect to the bacterial concentration. The activation energy was 83 kJ/mol. These results are consistent with the aqueous cholesterol diffusion model. The open pore agar microcapsule experimental effective diffusivity for lipoproteins at 37 degrees C was 6.7 x 10(-11) m2/s. Mass transfer across the microcapsule was not the limiting factor for the global rate.