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Pandoraea sp. B-6 assists the deep eutectic solvent pretreatment of rice straw via promoting lignin depolymerization

Liu, Dan, Yan, Xu, Zhuo, Shengnan, Si, Mengying, Liu, Mingren, Wang, Sheng, Ren, Lili, Chai, Liyuan, Shi, Yan
Bioresource technology 2018 v.257 pp. 62-68
Pandoraea, biorefining, depolymerization, droplets, enzymatic hydrolysis, lignin, lignocellulose, reducing sugars, rice straw, solvents, yields
Lignin depolymerization is a challenging process in biorefinery due to the recalcitrant and complex structure of lignin. This challenge was herein addressed via elaborating a new strategy of combining the bacterial strain Pandoraea sp. B-6 (hereafter B-6) with a deep eutectic solvent (DES) to pretreat rice straw (RS). In this approach, DES effectively depolymerized lignin yet easily caused sugar loss under severe conditions. B-6 not only overcame the obstacle of lignin droplets, but also significantly improved enzymatic digestibility. After B-6 assisted DES pretreatment, the reducing sugar yield increases by 0.3–1.5 times over DES pretreatment and 0.9–3.1 times over the untreated RS. Furthermore, a “cornhusking” mechanism explaining the improvement of the enzymatic digestibility by B-6 was suggested based on physicochemical characterizations of the untreated and pretreated RS. The findings provided a comprehensive perspective to establish a DES−microbial process for lignocellulose pretreatment.