Mining Natural Microbial Diversity for Tool-Compatible Chassis Discovery

Abstract The development of microbial bioprocesses for unconventional feedstocks requires chassis organisms capable of efficiently catabolizing complex substrates. However, model organisms, such as Escherichia coli, cannot inherently metabolize non-native compounds, and engineered pathways often result in poor growth on such substrates. Here, we present the Selection of Chassis Organisms Under Target conditions (SCOUT), a strategy for rapidly identifying genetically tractable environmental isolates that are compatible with existing synthetic biology tools. Using SCOUT, we isolated Pseudomonas postechii TPA1, a novel chassis exhibiting the fastest reported growth rate (0.78 h⁻¹) on terephthalic acid (TPA) to date. Engineering P. postechii TPA1 enabled direct biosynthesis of 505 mg/L of the natural blue pigment indigoidine from TPA. SCOUT further demonstrates its versatility by enabling the isolation of a ready-to-engineer host for styrene bioconversion. These results establish SCOUT as a powerful platform for expanding the microbial chassis diversity and accelerating the development of sustainable biorefinery processes.