A previously developed immobilization technique involving latex coatings on solid particulate supports was investigated further for penicillin G production by Penicillium chrysogenum. Several modifications were found to decrease the germination lag time, including a higher spore concentration, a thinner latex layer, an increased latex porosity, and a decreased drying time. This approach enabled the development of immobilized mycelial pellets within 2-3 days from the onset of biocatalyst preparation and incubation.A continuous immobilized-cell airlift bioreactor produced penicillin G in a series of runs in which the production phase lasted up to 30 days. The productivity of this system was 3-6 times greater than the productivity of the corresponding free-cell shake flask fermentation.