Leveraging protein phase separation for optimized biochemicals production

Microbial cell factories are pivotal platforms for converting lignocellulosic biomass into fuels and chemicals within the bioeconomy framework. Current bioproduction remains hindered by microbial sensitivity to inhibitors and process stresses, and by metabolic bottlenecks from poorly organized pathways and toxic intermediates that reduce titer, yield, and productivity. It is further limited by a narrow range of accessible bio-based chemicals. This review spotlights protein liquid-liquid phase separation (LLPS) as a powerful strategy to overcome these barriers. LLPS, a ubiquitous biophysical phenomenon, enables the formation of dynamic, membraneless condensates crucial for cellular functions like stress responses and metabolic channeling. Microbes leverage LLPS for protection against diverse stressors and to enhance metabolic efficiency by localizing enzymes and substrates. We critically assess how engineering microbial phase separation improves host fitness, streamlines metabolic flux to enhance economic performance, and enables in vivo assembly and functional integration of artificial metalloenzymes.