SynCom-Mediated Spatiotemporal Oxygen Control Enhances Lignocellulose Degradation and Nutrient Preservation

Lignocellulosic biomass holds immense potential as a renewable resource, yet its efficient valorization is hindered by structural recalcitrance and oxygen sensitivity in microbial systems. We engineered a synthetic microbial community (SynCom) comprising Lactobacillus plantarum, Bacillus subtilis, and Aspergillus niger to resolve the oxygen paradox in lignocellulose conversion. The SynCom strategically programmed spatiotemporal oxygen gradients via A. niger’s crabtree-negative metabolism, reducing headspace O₂ from 2% to <0.5% within 48 h and enabling L. plantarum dominance (>83% relative abundance) under stabilized anaerobic microniches. This orchestrated environment facilitated synergistic lignocellulose degradation, with B. subtilis’s GH5 cellulase and A. niger’s β-glucosidase driving 18.57% and 21.64% reductions in cellulose and hemicellulose content, respectively, by day 30. The SynCom achieved cellulose and hemicellulose contents reduced by 18.57% and 21.64% and surpassing aerobic fungal pretreatments, and 141.38 g/kg DM of crude protein retention, 40% higher than traditional systems, through rapid acidification (pH < 4.5) that stabilized microbial communities. Macrogenomics profiling revealed enzymatic cross-feeding (GH43 hemicellulase, CE10 esterase) and metabolic handoffs, while CAZyme analysis highlighted enriched glycoside hydrolases (GH43, GH51) critical for lignocellulose deconstruction. Field trials under realistic oxygen fluctuations (1–5% O₂) demonstrated 18.9% higher dry matter recovery than commercial inoculants, resolving the historical trade-off between aerobic delignification and anaerobic nutrient preservation. By bridging ecological niche engineering with industrial scalability, this work establishes SynComs as programmable platforms for sustainable biorefineries. Our findings redefine microbial consortia design, offering a blueprint for lignocellulose valorization in oxygen-fluctuating environments and advancing the circular bioeconomy through adaptable microbial solutions.