Optimization of Culture Conditions and Medium Composition for the Synthesis of Xylanase by Resting Neurospora sitophila Cells: Analysis of the Effects of Sugars on Xylanase Production Using the Resting Cell

Resting cells are microbial cells that have ceased to grow, but retain the ability to survive and synthesize products, and they retain biochemical reactivity required for enzyme synthesis. In this study, a system for cultivating resting cells for biosynthesis of xylanase from Neurospora sitophila was established, with xylanase activity and biomass measured before and after resting cell cultivation used as experimental indicators. The present resting system was used to investigate the effectiveness of certain sugars as induction factors of xylanase synthesis and to thereby determine the direct factors affecting enzyme synthesis. Single-factor tests and orthogonal experiments were utilized to determine the contents of the culture medium and conditions for resting cell cultivation. The results of this study indicate that using 0.8 g/L glucose as a source of carbon, 0.8 g/L sodium nitrate as a source of nitrogen, 0.1 g/L magnesium sulfate, an initial culture medium pH of 5.5, and a shaking speed of 180-200 rpm with 20 h of resting cultivation at 28 degrees C resulted in a maximum enzyme activity of 20.57 U/mL. The effects of sugars on the induction of xylanase were studied using this resting cell cultivation system, and it was determined that maltose had significant enzyme production-inducing effects, increasing enzyme activity by 52.23%, compared with the control. The present findings are expected to provide a theoretical basis for broadening the biotechnological applications of Neurospora sitophila and increasing the fermentation yield of xylanase.