Microbial polyhydroxyalkanoates: advances, omics-driven insights and industrial applications with a focus on Streptomyces sp.

Polyhydroxyalkanoates (PHAs) are microbially synthesized biopolyesters that have emerged as sustainable alternatives to conventional plastics due to their biodegradability, biocompatibility, and versatile material properties. Among various microbial producers, Streptomyces species have gained attention as promising yet underexplored candidates for PHA production because of their metabolic versatility, ability to utilize diverse substrates, and potential to synthesize structurally diverse polymers. This review highlights recent advances in PHA production by Streptomyces, focusing on metabolic pathways, omics-based insights, and bioprocess optimization strategies. Despite these advances, challenges such as complex genome organization, alternative metabolic routes, and limited understanding of PHA regulatory networks continue to constrain efficient production. Recent transcriptomic approaches, including RNA-Seq and iModulon analyses, have improved our understanding of the regulatory mechanisms governing PHA biosynthesis and accumulation. In parallel, optimization of culture conditions, including carbon and nitrogen sources, pH, and temperature, using statistical tools such as Taguchi design and Response Surface Methodology (RSM), has enhanced production efficiency. The use of renewable substrates and agro-industrial residues further supports sustainable and cost-effective PHA production. However, high production costs, low productivity, downstream processing limitations, and inadequate genetic engineering strategies remain major barriers to industrial-scale application. Integrating omics-driven insights, metabolic engineering, and advanced bioprocess optimization will be essential for achieving scalable and economically viable PHA production in Streptomyces. Graphical Abstract