Polyhydroxybutyrate production-oriented wastewater valorization: Aniline as a selective stress enabling non-sterile operation.

The valorization of industrial streams containing high concentration of aromatic compounds is of great significance yet remaining a critical challenge. Herein, an innovative strategy was proposed to transition the wastewater treatment from "removal-centered" to "recovery-oriented". Specifically, the newly isolated Cupriavidus sp. CY-1 realized the sustainable synthesis of value-added bioproduct polyhydroxybutyrate (PHB) from benzoate wastewater. For the first time, the upregulation of the ben and dan gene clusters in response to benzoate and aniline was demonstrated by transcriptome profiling, which supported efficient pollutant removal and PHB biosynthesis. Aniline not only boosted the PHB production but also created a selective stress, endowing Cupriavidus sp. CY-1 with excellent adaptability in complex environments. Accordingly, Cupriavidus sp. CY-1 dominated the microbial community (>70%) over 20 days in a bioreactor without sterilization, achieving efficient wastewater depuration and sustainable PHB synthesis (2.14 g L-1). More importantly, the substrate spectrum of Cupriavidus sp. CY-1 encompassed various aromatic compounds (e.g., phenol, 3-hydroxybenzoic acid, and 4-hydroxybenzoic acid), positioning it as a promising cell factory. The environmental benefits of the proposed strategy were verified by life-cycle assessment (LCA), demonstrating a 66.5% reduction in greenhouse gas emission. Therefore, this study developed a sustainable recovery-oriented wastewater valorization strategy that achieved simultaneous pollutant removal and PHB synthesis.