Spartina argentinensis valorization and process optimization for enhanced production of hydrolytic enzymes by filamentous fungus

Abstract

Hemicellulose is a major component of plant cell walls and xylan is the most predominant polysaccharide. Xylan degrading enzymes integrate the xylanolytic system. Xylanolytic enzymes were produced by fermentation by Aspergillus niger and Thermomyces lanuginosus grown on grass considered unsuitable for farming called Spartina argentinensis. Significant parameters: type of fermentation used (SmF or SSF), type of leaves of S. argentinensis (green or senescent) and conidia final concentration for xylanase production were screened and optimized. The main results showed that the highest levels of xylanolytic enzyme production were obtained by 1 × 105 conidia/mL of A. niger in SmF at 96 h, 30ºC, with a mixture of 20.20% of senescent and 79.80% of green leaves. The xylanase specific activity obtained was 62 U/mg, higher than the activity obtained (23 U/mg) in previous work (Taddia et al., 2019), and the concentration of xylanolytic production over that of glucanase activity was maximized five times. The optimized enzymatic extract obtained was characterized by LC-MS and HPLC of carbohydrates. Six enzymes were identified as constituents of the xylanolytic complex and seven carbohydrates. Moreover, the xylanolytic enzyme extract was stable for 30 days at 20 °C. Thus, S. argentinensis can be used within the framework of a circular economy, rendering a synergistic combination of the xylanolytic enzymes with industrial applications.