The production of the antibiotic patulin in a three phase fluidized bed reactor I. Effect of medium composition

The continuous and semi‐batch production of the antibiotic patulin by immobilized Penicillium urticae cells in a three phase fluidized bed reactor was investigated. A key factor for the success of the process was the limitation of the nitrogen source which increased the longevity of the biocatalyst while keeping cell growth at a low level. The continuous reactor was operated for 360 h during which time the effluent concentration of patulin was maintained at 0.25 mmol/L for 192 h. The total amount of patulin produced by the continuuous run was 35% greater than that obtained in a semibatch run. The pathway efficiency was 0.35 for 192 h indicating the biosynthetic pathway was operating at a high catalytic efficiency.