FUNGAL CELL IMMOBILIZATION ON ZEOLITE FOR PULLULAN PRODUCTION

Immobilization of Aureobasidium pullulans strain RP-1 cells by adsorpt ion on the aluminosilicate support zeolite was investigated. Pullulan production by the fungal cells immobilized on zeolite was slightly gre ater when the corn syrup-grown cells were adsorbed at pH 4.0 and 5.0 a lthough a slightly higher concentration of fungal cells was adsorbed a t pH 2.0 than at pH 4.0 or 5.0. The lowest level of adsorbed cells occ urred at pH 7.5. The highest polysaccharide levels were elaborated by strain RP-1 cells adsorbed on the zeolite at pH 4.0 or pH 5.0 when the immobilized cells were screened for pullulan production. In contrast, pullulan synthesis by cells adsorbed on the zeolite at pH 2.0 or pH 2 .5 was lowest. It was possible to use the cells immobilized on the zeo lite at pH 4.0 or 5.0 for two 7-day cycles of pullulan elaboration wit h comparable pullulan concentrations produced in both cycles. During t he second 7-day cycle, polysaccharide production by the cells immobili zed at pH 4.0 or 5.0 was found to be slightly increased relative to th e initial cycle.