The escalating global plastic pollution crisis has intensified the demand for bio-based, biodegradable alternatives, such as polyhydroxybutyrate (PHB). Among various sources, microalgae-derived PHB has emerged as a promising and sustainable biomaterial. This study investigated PHB production in Scenedesmus sp., focusing on growth modes, time intervals, and nutrient optimization to enhance yields. Response surface methodology (RSM) was employed to evaluate the effects of nitrogen (N) and carbon (C) concentrations on PHB accumulation. Heterotrophic cultivation of Scenedesmus sp. over 8 days achieved the highest PHB content compared to phototrophic and mixotrophic modes. Optimization using RSM identified N and C concentrations of 0.409 g L −1 and 1.583 g L −1 , respectively, resulting in a PHB yield of 3.20 ± 0.28%. Characterization of the recovered biopolymer revealed thermal stability below 230 °C, indicating potential applicability in industrial bioplastic production. Fourier transform infrared spectroscopy (FTIR) confirmed the presence of characteristic ester bonds, validating the polymer identity as PHB. Furthermore, pretreatment strategies were explored to improve recovery efficiency, whereby sonication enhanced PHB yield to 4.89 ± 0.65%. These findings demonstrate that Scenedesmus sp. can serve as a viable microalgal platform for PHB production, with optimization strategies significantly influencing yield outcomes. This study underscores the potential of integrating nutrient regulation and pretreatment techniques to advance microalgae-based bioplastic production and contribute to sustainable solutions for mitigating plastic pollution. • Scenedesmus sp. demonstrated highest PHB production under heterotrophic growth. • Optimization of nutrients (nitrogen and carbon) revealed 3.20% PHB content. • Sonication pretreatment enhanced PHB yield to 4.89%. • PHB quantification using gravimetric practices is subject to variability.
Hassan et al. (2026) studied this question.