Studies of pectic enzymes produced by Talaromyces flavus in submerged and solid substrate cultures

Tons of peel and rag are generated each year by industries of citrus fruit juices. These by-products are used either for the elaboration of pectin or as substrate for enzyme production. Talaromyces flavus produces extracellular pectinesterase and polygalacturonase after 24 h in submerged culture supplemented with 0.5-0.8% citrus pectin preceded by preculture for 24 h in 2% (w/v) sucrose or in solid substrate culture on passion fruit peel, lemon or orange pulp pellets after 3-6 days of incubation. Chromatographic profiles in a CM-Sepharose column of liquid and solid cultures were very similar, consisting of one endopoligalacturonase (endo-PG I) and one pectinolytic complex constituted by an endopoligalacturonase (endo-PG II) and pectinesterase. Pectin and pectate lyases were undetectable in both media. In Talaromyces flavus the synthesis of pectinases was repressed by glucose and finally controlled by the concentration of products from pectic enzymes degradation.