Mining Natural Microbial Diversity for Tool-Compatible Chassis Discovery

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.