Pectin lyase production by Penicillium griseoroseum grown in sugar cane juice in repeated batch cultures

Penicillium griseoroseum cultured in the presence of sucrose and yeast extract produces pectin lyase (EC 4.2.2.10) (PL) in the absence of its natural inducer pectin. This fungus was cultured in a fermenter at an aeration rate of 0.5 l/min for the first 25 h and 1.0 l/min for the remainder of the culture period, and at a stirring rate of 200 rev/min for the entire culture period. Fungal spores were inoculated directly into the fermenter at a final concentration of 5 × 10⁴ spores/ml. The fungus was cultured in minimal medium supplemented with powdered dehydrated sugar cane juice, producing PL without added yeast extract. Maximum PL activity (0.067 IU/ml) was obtained after 65 h in batch culture. Pellet morphology of the mycelia made it possible to carry out three cycles of repeated batch culture. The same medium was used for renewal as for the single batch culture. The initial cycle was 53 h, after which approximately 0.103 IU/ml of PL was obtained. After this period, the medium was renewed and fermentation continued for two more cycles, which lasted approximately 20 h. Activity of PL obtained in the second cycle was approximately 0.118 IU/ml and in the third, approximately 0.109 IU/ml.