Paper Industry Wastes as Carbon Sources for Aspergillus Species Cultivation and Production of an Enzymatic Cocktail for Biotechnological Applications

Abstract

In the present work, the production of enzymatic cocktails from different Aspergillus species grown in eucalyptus chips has been investigated. In addition, hydrolysis of the eucalyptus chips and paper sludge by these cocktails was performed, and the products were identified. A. awamori, A. brasiliensis, A. clavatus, A. flavus and A. terreus were cultivated in minimal medium, pH 6.5, 1% eucalyptus chips with 10⁷ spores/mL, at 30°C and A. niveus was cultivated at 37°C, 120 rpm (all were grown for 5 d). Arabinanase, endoglucanase, mannanase, xylanase and xyloglucanase activities were quantified using 1% natural substrates and, arabinofuranosidase, β-glucosidase, β-xylosidase and cellobiohydrolase activities were quantified with 2 mM of synthetic substrates, at 50°C. A. brasiliensis and A. niveus showed high endoglucanase, β-xylosidase and cellobiohydrolase (cellulases) activities and, together, they were able to produce large amounts of arabinanase, arabinofuranosidase, β-xylosidase, mannanase and xyloglucanase (hemicellulases). A. clavatus presented the highest activity for xylanase. Saccharification was performed by incubating the crude extracts with 3% eucalyptus chips and 3% paper sludge, for 24 and 48 h at 50°C. The released products were then observed by Thin Layer Chromatography (TLC). During paper sludge saccharification, three extracts (A. brasiliensis, A. niveus and A. clavatus) were combined and released a total of 12.30 μmol/mL of reducing sugars after 48 h. The TLC presented high amounts of glucose, xylose, xylotriose and other oligosaccharides. These data suggest the great potential of enzymatic cocktail production using eucalyptus chips as substrate, which would be an inexpensive and ecologically friendly alternative for obtaining enzymes with great potential for biotechnological application.