Biodetoxification of acid-pretreated corncob hydrolysate for bacterial cellulose production based on Paecilomyces...

Inhibitors present in lignocellulosic hydrolysates severely hinder bacterial cellulose (BC) production. This study aimed to develop a biodetoxification strategy to facilitate BC production from lignocellulosic hydrolysate. Notably, following 2 g/L furfural addition, the BC yields of Komagataeibacter xylinus (K. xylinus) 2955 and K. xylinus GX08 decreased from 4.6 to 0.6 g/L and from 1.3 to 0.2 g/L, respectively. The detoxifying strain Paecilomyces variotii (P. variotii) 23 could completely remove furfural within 48 h. After separate biodetoxification and fermentation, BC yields increased significantly, reaching 5.3 g/L for K. xylinus 2955 and 5.2 g/L for K. xylinus GX08, corresponding to 5.6 and 25.0 fold increases compared with that in the undetoxified medium. Interestingly, furoic acid, a product generated by P. variotii from furfural, was found to promote BC production in K. xylinus GX08. When 1.0-2.0 g/L furoic acid was added, K. xylinus GX08 consumed 0.7-0.9 g/L of it, boosting BC production from 1.3 to 4.9 g/L. To simplify the detoxification process, a simultaneous biodetoxification and fermentation (SiBF) method was developed, which allowed BC titers to reach 5.1 g/L for K. xylinus 2955 and 5.2 g/L for K. xylinus GX08 in furfural-containing medium with no observable reduction in glucose-to-BC conversion rate. Microbial dynamics analysis showed that in the later stage of SiBF, the forming BC membrane reduced oxygen availability in the medium, thereby restricting P. variotii growth and its competition for glucose. Furthermore, the SiBF strategy was successfully applied to acid-pretreated corncob hydrolysate, yielding 5.3-5.4 g/L of BC.