Optimizing the detoxification conditions of distiller's grains hydrolysate for tetramethylpyrazine fermentation by Bacillus sp. TTMP20

Abstract

Distiller's grains (DGS) are the main byproduct of the brewing industry and a type of lignocellulosic biomass. In this study DGS were pretreated with water, dilute sulfuric acid, and sodium hydroxide to obtain hydrolysates for the fermentation of tetramethylpyrazine (TTMP). Acid-treated hydrolysate produced the highest TTMP yield. Then detoxification conditions of acid-treated hydrolysate including activated carbon dosage, pH, temperature, and time were optimized for the removal of some inhibitors such as acids, phenols, furfural and 5-hydroxymethyl-2-furaldehyde (HMF), and TTMP production. Under optimal detoxification conditions (activated carbon dosage of 3.0%, pH of 4.0, temperature of 60 ℃, and time of 60 min), almost all inhibitors were removed (83.82% acids, 96.47% phenols, 94.61% furfural and 91.87% HMF). In comparison to the control, this improved detoxification boosted the TTMP yield of Bacillus sp. TTMP20 by 1.27 times. Our strategy provided a suitable way for TTMP production from DGS, which achieved efficient resource utilization of industrial waste DGS.