Polygalacturonases (PG) are pectinolytic enzymes that have technological, functional and biological applications in food processing, fruit ripening and plant-fungus interactions, respectively. In the present, a microtitre plate methodology was used for rapid screening of 61 isolates of fungi from Aspergillus section Nigri to assess production of endo- and exo-PG. Studies of scale-up were carried out in a fixed bed reactor operated under different parameters using the best producer strain immobilised in orange peels. Four experiments were conducted under the following conditions: the immobilised cells without aeration; immobilised cells with aeration; immobilised cells with aeration and added pectin; and free cells with aeration. The fermentation was performed for 168 h with removal of sample every 24 h. Aspergillus niger strain URM 5162 showed the highest PG production. The results obtained indicated that the maximum endo- and exo-PG activities (1.18 U·mL−1 and 4.11 U·mL−1, respectively) were obtained when the reactor was operating without aeration. The microtitre plate method is a simple way to screen fungal isolates for PG activity detection. The fixed bed reactor with orange peel support and using A. niger URM 5162 is a promising process for PG production at the industrial level.

Tannase is an enzyme that hydrolyzes esters and lateral bonds of tannins, such as tannic acid, releasing glucose and gallic acid and stands out in the clarification of wines and juices. Fungi of the genera Aspergillus and Penicillium are excellent producers of this enzyme. The search for fungi that produce high levels of tannase as well as new substrates for the enzyme production by the SSF is required. The objectives of this study were to evaluate the production of tannase by Aspergillus and Penicillium species through SSF using leaves and agroindustrial waste barbados cherry and mangaba fruit as substrate, select the best producer, optimize production, characterize the crude enzyme extract, and apply it the clarification of grape juice. Selecting the best producer was performed by planning Placket-Burman and RSM. P. montanense showed highest activity with 41.64 U/mL after 72 h of fermentation residue using barbados cherry, with 3.5% tannic acid and 70% moisture. The enzyme showed the highest activity at pH 9.0 and 50°C. The tannase of P. montanense was stable over a wide pH range and temperature and, when applied to grape juice, showed higher efficiency by reducing 46% of the tannin content after incubation 120 m.

The partitioning and purification of polygalacturonases (PG) produced by Aspergillus niger URM 5162 were investigated in aqueous two-phase systems (ATPS), formed by polyethylene glycol and phosphate salts (PEG/phosphate). To evaluate the effect of the 4 independent variables-molar mass of polyethylene glycol (PEG) (400-8000 g/mol-M PEG), PEG concentration (12.5-17.5%, w/w-C PEG), phosphate concentration (15-25%, w/w, C PHOS) and pH (6.0-8.0)-on the 4 response variables: partition coefficient (K), activity yield (Y), purification factor (PF) and selectivity (S), a factorial design (2 4) was used. The endopolygalacturonases (endo-PG) and exo-polygalacturonase (exo-PG) were preferentially partitioned in the top phase. For endo-and exo-PG, the highest values for the response variables K (1.23 and 2.40), Y (74.04% and 17.97%), PF (8.18 and 1.98) and S (24.68 and 48.07), respectively, were obtained for a C PEG of 12.5% (w/w), M PEG of 8000 g/mol, and C PHOS of 25% (w/w) at pH 6.0. These conditions were considered the most suitable for the purification of PG produced by A. niger URM 5162. Furthermore, the most important independent variables for endo-and exo-PG were C PHOS and M PEG , respectively. All independent variables studied and their interactions significantly influenced the response variables. According to these results, the PEG/phosphate system is a useful cost-effective alternative for purification of PG produced by A. niger URM 5162.