Integrated base editing and microfluidics boost microbial lipid production from lignin

Lignin, a recalcitrant aromatic biopolymer, is a promising feedstock for sustainable valorization. Here, we investigated the transcriptional response of Curvularia clavata J1 to alkali lignin (AL) and established a Cu²⁺-inducible MCM5-AID base editor for genome-wide C-to-T/G-to-A mutagenesis. Transcriptomics revealed AL-induced upregulation of electron transport, lipid catabolism, and iron homeostasis. Droplet microfluidics enabled ultrahigh-throughput screening, identifying mutant M6 with superior traits. M6 achieved 49 % lipid of dry cell weight (DCW) (36 % increase) and 228.58 U/L laccase activity (75 % increase) in shake flasks, further validated in bioreactors with 51 % DCW lipid (33 % increase) and 240.43 U/L laccase activity (87 % increase). Genome sequencing confirmed random C-to-T mutations, while transcriptomics indicated enhanced fatty acid, steroid, and glycerolipid biosynthesis redirecting carbon flux to oil-enriched single-cell protein. This work provides an integrated framework for lignin biotransformation and highlights the potential of synthetic biology-microfluidics integration for precise fungal engineering.