Direct Conversion of Minimally Pretreated Corncob by Enzyme-Intensified Microbial Consortia

The presence of diverse carbohydrate-active enzymes (CAZymes) is crucial for the direct bioconversion of lignocellulose. In this study, various anaerobic microbial consortia were employed for the degradation of 10 g/L of minimally pretreated corncob. The involvement of lactic acid bacteria (LAB) and...

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Main Authors: Alei Geng, Nana Li, Anaiza Zayas-Garriga, Rongrong Xie, Daochen Zhu, Jianzhong Sun
Format: Article
Language:English
Published: MDPI AG 2024-09-01
Series:Agriculture
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Online Access:https://www.mdpi.com/2077-0472/14/9/1610
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Summary:The presence of diverse carbohydrate-active enzymes (CAZymes) is crucial for the direct bioconversion of lignocellulose. In this study, various anaerobic microbial consortia were employed for the degradation of 10 g/L of minimally pretreated corncob. The involvement of lactic acid bacteria (LAB) and a CAZyme-rich bacterium (<i>Bacteroides cellulosilyticus</i> or <i>Paenibacillus lautus</i>) significantly enhanced the lactic acid production by <i>Ruminiclostridium cellulolyticum</i> from 0.74 to 2.67 g/L (<i>p</i> < 0.01), with a polysaccharide conversion of 67.6%. The supplement of a commercial cellulase cocktail, CTec 2, into the microbial consortia continuously promoted the lactic acid production to up to 3.35 g/L, with a polysaccharide conversion of 80.6%. Enzymatic assays, scanning electron microscopy, and Fourier transform infrared spectroscopy revealed the substantial functions of these CAZyme-rich consortia in partially increasing enzyme activities, altering the surface structure of biomass, and facilitating substrate decomposition. These results suggested that CAZyme-intensified consortia could significantly improve the levels of bioconversion of lignocellulose. Our work might shed new light on the construction of intensified microbial consortia for direct conversion of lignocellulose.
ISSN:2077-0472