Enhancement of novel cello-xylosome saccharification performance via microbial surface display on lignocellulosic feedstocks.

Abstract

Cellulosomes are regarded as the most intricate naturally occurring cellulolytic systems. This study reports the design and surface assembly of a novel artificial cello-xylosome on Escherichia coli BL21:ΔCsgA cells. This synthetic complex incorporates two highly active enzymes previously sourced from sheep rumen microbiota, namely the glucanase IDSGLUC5-28 and the xylanase IDSXYN10-1. The structural integrity of the designer cello-xylosome was confirmed using a combined approach involving western blot analysis, zymography, and immunofluorescence microscopy. Substrate hydrolysis assays demonstrated that whole cells displaying the surface-anchored cello-xylosome predominantly released mono- and disaccharides from glucan- and xylan-based substrates, aligning with the product profiles generated by the free enzymes. Following a 48-h reaction, the engineered cells released 1.20 and 0.51 mg/mL of reducing sugars from peanut and rice straws, respectively. Structural characterization of these natural feedstocks revealed severe disruption of the fiber structures, along with reduced particle size distribution and decreased crystallinity index. Notably, the engineered cells exhibited reasonable reusability toward peanut straw over multiple bioprocessing cycles, providing a distinct advantage over free enzymes. In summary, this study provided a new strategy for environmental remediation, particularly for resource-oriented and renewable recycling of agricultural waste.