Non-model microorganisms for polyhydroxyalkanoates production: Diversity, industrial readiness, and future engineering strategies

Polyhydroxyalkanoates (PHAs) are promising biodegradable polymers, yet their commercialization remains constrained by feedstock cost, sterility requirements, downstream recovery challenges, and limited process scalability. Although numerous microorganisms have been reported to produce PHAs, current research lacks a systematic framework for evaluating and comparing their industrial readiness, making it difficult to distinguish biologically interesting strains from those with realistic translational potential. To address this gap, this review proposes a Chassis Maturity Framework (CMF) that systematically evaluates non-model PHA-producing microorganisms using integrated biological, engineering, process, economic, environmental, and scalability criteria. Representative archaea, bacteria, fungi, and protists are assessed to differentiate exploratory, promising, and scale-up-ready microbial chassis based on CMF, while enabling technologies such as CRISPR-based genome engineering and AI/ML-assisted optimization are discussed for their demonstrated potential to accelerate chassis domestication. Finally, the review aims to provide a structured basis for prioritizing microbial chassis, identifying critical development bottlenecks, and guiding future research toward industrially relevant PHA manufacturing. In this context, the industrial value of non-model PHA producers should be evaluated not solely by polymer accumulation, but also by their potential to reduce process complexity and production costs.