Background: The recalcitrance of lignocellulosic biomass offers a series of challenges for biochemical processing\ninto biofuels and bio-products. For the first time, we address these challenges with a biomimetic system via a mild\nyet rapid Fenton reaction and lignocellulose-degrading bacterial strain Cupriavidus basilensis B-8 (here after B-8) to\npretreat the rice straw (RS) by mimicking the natural fungal invasion process. Here, we also elaborated the mechanism\nthrough conducting a systematic study of physicochemical changes before and after pretreatment.\nResults: After synergistic Fenton and B-8 pretreatment, the reducing sugar yield was increased by 15.6ââ?¬â??56.6%\nover Fenton pretreatment alone and 2.7ââ?¬â??5.2 times over untreated RS (98 mg gâË?â??1). Morphological analysis revealed\nthat pretreatment changed the surface morphology of the RS, and the increase in roughness and hydrophilic sites\nenhanced lignocellulose bioavailability. Chemical components analyses showed that B-8 removed part of the lignin\nand hemicellulose which caused the cellulose content to increase. In addition, the important chemical modifications\nalso occurred in lignin, 2D NMR analysis of the lignin in residues indicated that the Fenton pretreatment caused partial\ndepolymerization of lignin mainly by cleaving the Ã?²-O-4 linkages and by demethoxylation to remove the syringyl (S)\nand guaiacyl (G) units. B-8 could depolymerize amount of the G units by cleaving the Ã?²-5 linkages that interconnect\nthe lignin subunits.\nConclusions: A biomimetic system with a biochemical Fenton reaction and lignocellulose-degrading bacteria was\nconfirmed to be able for the pretreatment of RS to enhance enzymatic hydrolysis under mild conditions. The high\ndigestibility was attributed to the destruction of the lignin structure, partial hydrolysis of the hemicellulose and partial\nsurface oxidation of the cellulose. The mechanism of synergistic Fenton and B-8 pretreatment was also explored to\nunderstand the change in the RS and the bacterial effects on enzymatic hydrolysis. Furthermore, this biomimetic\nsystem offers new insights into the pretreatment of lignocellulosic biomass.
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