Produção e caracterização da amilase de um novo isolado de Aspergillus sp. em fermentação em estado sólido utilizando resíduos agroindustriais

Abstract

The hydrolysis of starchy polysaccharides depends on a group of enzymes that belong to the amylolytic complex. The cultivation of filamentous fungi through solid-state fermentation (SSF), especially those that use agro-industrial residues, enables the production of enzymes with potential applications in industry. In this context, the objective of this work was to optimize the production of amylases by the fungus Aspergillus sp. in SSF using different carbon sources, including agro-industrial residues, as well as performing the biochemical characterization of the crude enzyme. Different substrates were tested as a carbon source to produce amylase by the microorganism, as well as different supplementation with nitrogen and carbon sources. The temperatures of 25, 30, 35 and 40 ºC and cultivation times of 1 to 10 days were also evaluated. It was observed that the highest production of amylases was in medium containing broken rice supplemented with 1% (w/w) of almond oil cake when cultivated at 25 °C for 2 days, with 14.45 ± 0.45 U.g-1. Subsequently, the biochemical characterization of the enzyme was carried out, evaluating the effect and stability at pH and temperature, in addition to the effect of salts and chemical agents. The enzyme showed maximum activity at pH 5.0 and maintained its stability in the pH range from 4.0 to 5.5. The optimum temperature of the enzyme occurred at 50 ºC, with enzymatic thermostability at 40 ºC for 4 h. The presence of metal ions Mn2+, Mg2+, Ca2+ and Ni2+ were able to increase the enzyme activity by 66.79 ± 5.09, 55.78 ± 1.05, 18.58 ± 2.76 and 26.98 ± 5.54 %, respectively. Thus, it can be concluded that the amylase produced by Aspergillus sp., by exhibiting enzyme production in a low-cost medium and presenting promising biochemical characteristics, is suitable for possible industrial applications.