Optimization and characterization of polyhydroxybutyrate produced by Vreelandella piezotolerans using orange peel waste

Microorganisms are promising, cost-effective, and sustainable producers of bioproducts, including polyhydroxybutyrate (PHB), a biodegradable polymer that offers an eco-friendly alternative to synthetic plastics. This study investigates PHB production using the newly isolated Vreelandella piezotolerans with orange peel waste as the substrate. Notably, this is the first research to optimize PHA production with V. piezotolerans, utilizing Design Expert 7.0 software. Various bacterial isolates were screened, and the most efficient strain, MH46, was identified as V. piezotolerans through 16 S rRNA sequencing and registered in GenBank (accession number PP826285). Single-factor optimization was conducted to determine optimal fermentation conditions. The results of the single-factor optimization were used to conduct Plackett-Burman design experiments. The response surface optimization was then completed. Results revealed that temperature, agitation rate, and inoculum size significantly influence PHA production. The extracted PHB was characterized using GC-MS, NMR, FTIR, XRD, and thermal analysis. This study is the first to report PHB accumulation by V. piezotolerans using orange peel waste as the sole carbon source.