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 extr act 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 cul ture period, and at a stirring rate of 200 rev/min for the entire culture p eriod. Fungal spores were inoculated directly into the fermenter at a final concentration of 5 x 10(4) spores/ml. The fungus was cultured in minimal m edium 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 poss ible to carry out three cycles of repeated batch culture. The same medium w as 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 cycl es, 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 I U/ml.