Utilização de bagaço de malte da indústria cervejeira para produção de amilase por amostras de Aspergillus spp. isolados de amostras do solo da caatinga de Pernambuco.

Abstract

The production of microbial enzymes through fermentation processes has undergone constant technical-scientific evolution, mainly in the application of agro-industrial residues in these bioprocesses. Amylases are enzymes that hydrolyze starch molecules releasing several products including dextrins and progressively small polymers composed of glucose units. Malt bagasse represents around 85% of the total waste generated in a brewery. Filamentous fungi have a high potential for converting macromolecules into biotechnological products, especially the Aspergillus genus. The evaluation of the amylase production potential was carried out in Aspergillus spp. (UCP1275, UCP6119, UCP1295 and UCP1261) isolated from soils of the Northeastern Caatinga, through the process of submerged fermentation in standard medium (Adams, 1990): yeast extract 2 g/L; 1 g/L KH2PO4; MgSO4.7H2O 0.5 g/L, containing starch as a carbon source (10g/L), and selection with an alternative medium with malt bagasse residue (10g/L) to replace starch. Strain 1 (UCP1275) selected in an alternative medium, was conducted to the experiments of the complete factorial design 23 (12 conditions), with the independent variables: initial pH (5 to 7), temperature (24 to 32ºC) and malt bagasse concentration (5 to 15g/L). The tests were conducted for 96 hours, 150 rpm and 28ºC. In condition 1, the maximum enzymatic activity (7.59 U/mL) was reached. Other response variables were also evaluated: biomass production (9.99 g/L) and final pH (increase in absolute value under all conditions). Condition 1 was used to study the kinetics of amylase enzymatic activity during 168h. The Aspergillus spp. UCP1275 was the one with the greatest potential to bioconvert malt bagasse residue into amylase, favoring the formulation of a new production medium.