Polyhydroxyalkanoates (PHAs) are bioplastics that can serve as substitutes for petroleum-based plastics with the advantages of being biodegradable, biocompatible, and biobased. The microbial production of polyhydroxyalkanoates is generally conducted in the presence of sugar mixes rich in monosaccharides. In this study, molecular and cultural approaches based on forest soils enriched with hydrocarbon complexes led to the identification and isolation of microbial strains affiliated with Paraburkholderia sp. that dominated the microbial communities that are recognized among the top polyhydroxyalkanoates producers. The genome sequencing of those isolated affiliated strains showed that compared to the reference type strain of their species, they harbored more gene copies of the enzymes involved in PHB synthesis. The microbial conversion of sugar mixes for the newly isolated strains showed a higher PHB production (g/L) and content (%) than was exhibited by the reference strain type of that genus Paraburkholderia for PHB production (P. sacchari LMG 19450T).