In silico elucidation of polyhydroxyalkanoate biosynthesis pathways in Brevibacterium daeguense and Brevibacterium yomogidense.

Polyhydroxyalkanoates (PHAs) are biodegradable polyesters synthesized by diverse bacteria; however, their distribution within the genus Brevibacterium remains poorly characterized. In this study, we performed a comprehensive in silico analysis of publicly available genomes to investigate the presence, organization, and evolutionary context of PHA biosynthetic pathways in Brevibacterium daeguense and Brevibacterium yomogidense. Comparative genomic screening of 59 Brevibacterium genomes identified coherent PHA-associated gene clusters exclusively in these two species. Both genomes encoded two distinct phaC homologs, displaying conserved catalytic residues and domain architectures consistent with functional PHA synthases. Genomic neighborhood analyses revealed a non-canonical operon organization, lacking accessory subunits typically observed in other PHA synthase classes. Synteny comparisons and sequence similarity patterns suggest a potential horizontal acquisition scenario, although formal phylogenomic reconstruction was beyond the scope of the present study. Metabolic context analysis indicates that modular precursor supply routes potentially link central carbon metabolism and β-oxidation to PHA biosynthesis. Overall, this study establishes a genome-based framework supporting the predicted biosynthetic capacity for PHA production in these species and provides a foundation for future functional validation, evolutionary investigation, and metabolic engineering exploration.