Being biodegradable and biocompatible natural polymer, poly-β-hydroxybutyrate (PHB) drew the attention of scientists to substitute synthetic plastics in our daily lives. However, its industrial production is hampered by its high cost. In this study, an extensive screening program was done to isolate bacteria with high PHB productivity from agricultural fields and develop a cost-effective PHB production. A promising bacterial isolate Acinetobacter baumannii P39 was recovered and identified using 16S ribosomal gene sequencing. It produced 24% PHB per dry weight after 48 h. Several experiments were conducted to optimize the composition of the culture medium and environmental factors for the selected isolate. Results revealed that 60% aeration, 28°C incubation temperature and initial pH 7.5 showed the highest productivity. Besides, 0.7% corn oil and 0.1 g/L peptone were the best carbon and nitrogen sources, respectively. Substituting glucose with corn oil led to a 23% reduction in total input cost and an estimate price for 1kg PHB is 20.5 L.E. Strain improvement by UV mutation succeeded in improving PHB production by two fold in the selected mutant P39M2. Finally, this study valorizes usage of Acinetobacter isolate in PHB production in addition to solving the critical problem of high cost of production.