Candida rugosa ATCC14830 cells have high tendency to make flocculent masses by entanglement of the mycelium-like shaped cells and can be well immobilized in porous polyvinyl formal (PVF) resin. Moreover, Candida lipolytica cells, which became to show a mycelium-like shape by mutation, were also immobilized in PVF resin.
These C. rugosa and mutant C. lipolytica cells were immobilized in PVF resins and cultured by the draw-fill method 2–3 times. These C. rugosa and C. lipolytica cells could decompose L-lactic acid and produce bio-surfactant liposan, respectively. Because high cell densities could be attained in immobilized systems, the total productivity in repeated-batch operations with immobilized cells was higher than those in batch operations with free cells. Moreover, the decomposed amount of L-lactic acid did not decrease during the repeated-batch operations, because the number of immobilized cells in PVF resin was kept almost constant.