Valorization of corn cob for the obtention and purification of endoglucanase produced by SSF

Abstract

Agro-food by-products contain valuable nutrients which are wasted. In this work, solid-state fermentation (SSF) was carried out using corn cob as substrate for endoglucanase production. The radial growth of three fungal strains -Trichoderma harzianum T104, Aspergillus niger GH1 and Aspergillus niger NRRL3- was analyzed in order to select the most appropriate. Radial growth data were analyzed with a mixed linear model for longitudinal data and no statistically significant differences were found between both A. niger strains. Endoglucanase was separated from the extract of A. niger GH1 by fast protein liquid chromatography (FPLC).The highest endoglucanase activity was detected in fraction number three collected from FPLC corresponding to 72 h of SSF. Seven bands in a range from 24 to 50 kDa, which correspond to endoglucanase from fungal extract, were detected by zymogram analysis. According to protein quantification performed by the ImageJ software, 85% of the proteins present in the samples collected by FPLC corresponded to endoglucanase proteins. The purified endoglucanase retained about 100% of its catalytic activity at 30 °C and 50 °C and was stable in a pH range between 4.00-6.00. These properties make this isolated enzyme suitable for industrial applications such as the saccharification process for bioethanol production.