Resumo

Pectinases are utilized to clarify juice, beer and wine in food industries. They are produced by Aspergillus, Penicillium, Trichoderma and Rhizopus species in fermentative processes. This work aimed to compare growth, exopolygalacturonase production, reducing sugar concentration and pH during fermentation of pectin by two new Penicillium sp. isolates (T9.1 and T3.1) to select the best strain, nitrogen source and carbon source concentration. Pectin concentration (0.5% and 1%) and nitrogen source (0.4 g/l yeast extract or ammonium sulphate) were varied. Initial pH was adjusted to 6.0. Fermentations were conducted at 30ºC and 150 rpm for 7 days. Exopolygalacturonase activity and growth (dry weight) were determined. Strain T9.1 produced low enzyme activities, with a maximum of 0.32 U.ml-1min-1 ± 0.09 obtained on 0.5% pectin/yeast extract. Supplementing media with ammonium sulphate or 1% pectin decreased enzyme production by T9.1. Strain T3.1 produced 1.13 U.ml-1min-1 ± 0.19 of exopolygalacturonase after 4 days of fermentation in medium supplemented with 1% pectin/ammonium sulphate. T3.1 exopolygalactuorase production occurred earlier (2-3 days) in cultures supplemented with yeast extract, but the activities produced were about half of the obtained with 1% pectin/ammonium sulphate. Growth of T3.1 was similar in media supplemented with yeast extract (4.12 mg/ml ± 0.34; 1% pectin, 3 days) and ammonium sulphate (3.77 mg/ml ± 0.3; 1% pectin, 7 days) but the time to reach the maximum was different. 1% pectin duplicated growth of both strains, in comparison to 0.5% pectin. In all cultures, pH dropped during the first 3-4 days and then raised to near 6-7, whereas ammonium sulphate resulted in lower pH values. Reducing sugars in the filtrates diminished with time, whereas its decrease coincided with growth and pH increase. Results revealed differences in growth profile and exopolygalacturonase production by both strains studied, and allowed conclude that Penicillium sp. T3.1 can be further employed to study and improve pectinase production. The best pectin concentration (1%) and nitrogen source (ammonium sulphate) for exopolygalacturonase production by T3.1 were determined as starting conditions for future experiments. Thus, analyzing fermentation profile in different conditions was efficient to direct studies on development of fungal process for pectinase production.