Solid-state fermentation of distillers grains with Aspergillus pachycristatus for echinocandin B biosynthesis

Abstract

An innovative strategy has been developed to utilize distillers grains (DGS) as a substrate for solid-state fermentation (SSF) to synthesize echinocandin B (ECB). In this study, the optimal fermentation parameters for Aspergillus pachycristatus were determined as follows: an inoculation density of 1 × 10⁶ spores/gram dry substrate (gds), pH maintained at 6.0, temperature controlled at 30℃, moisture kept at 60% (v/w), and cultivation duration set to 6 days. Engineered Trichoderma reesei is employed to pretreat DGS and enhance the release of nutrient substances for subsequent utilization by A. pachycristatus. Furthermore, incorporating an amino acid cocktail augments metabolic flux towards ECB synthesis. Ultimately, these efforts result in a production yield of 2017.6 μg/gds for ECB. This study not only provides a solution for the high-value utilization of DGS but also presents an efficient, cost-effective, and environmentally friendly synthetic process within the circular economy framework for industrial production of ECB.