Production and characterization of endo-polygalacturonase from Aspergillus niger in solid-state fermentation in double-surface bioreactor

Abstract

Endo-polygalacturonase (endo-PG) production by Aspergillus niger T0005/007-2 in solid medium with 170 mm of height was evaluated in a cylindrical double surface bioreactor in 96-h experiments. Cell concentration close to 92 mg.g-1dm (mg per g of dry medium) in the standard condition (static) was achieved, whereas in tests under forced aeration of 1.4 and 2.8 L.min-1.Kg-1mm (L of air per minute per Kg of moist medium) and with the central shaft fungal biomass attained approximately 100 mg.g-1dm. Superior endo-PG activity was obtained with the centralshaft system, 78 U.g-1dm (units per g of dry medium). Forced aeration and pressure pulse showed no positive effect on the production of endo-PG, 45 U.g-1dm and 28 U.g-1dm, respectively. None of the conditions evaluated was efficient for medium temperature control. Endo-PG was stable up to 40°C. The activity decreased in 50% after 120 minutes at 50°C, which is a temperature normally found during this process.