Metabolic channelling in Rhodopseudomonas palustris for diversification and sustainability assessment of polyhydroxyalkanoates

Abstract

The increasing demand for sustainable alternatives to petrochemical-based plastics necessitates efficient biopolymer production methods. This study isolated and explored Rhodopseudomonas palustris SVMIICT10 for the biosynthesis of polyhydroxyalkanoates under the effect of levulinic acid as a co-feed with pyruvate and nutrient supplementation, following the influence of the microenvironment. By evaluating anaerobic, aerobic, and transition conditions along with variations in nutritent availability, the study demonstrated the strain's potential and metabolic diversity in PHA productivity. This approach led to the synthesis of a spectrum of PHAs with varied alkyl groups, resulting in scl-homopolymer (P-3HB), scl-copolymer (P-3HB-3HV), and copolymers combining scl and mcl-PHA (P-3HB-co-3HD). Notably, under anaerobic conditions with pyruvate, the strain utilized 70% of the substrate, yielding 3.66 g L⁻¹ biomass and 1.055 g L⁻¹ PHA, while aerobic conditions led to copolymer synthesis. Detailed physicochemical analyses (GC-MS, TGA, DSC, XRD, and FTIR) revealed the biomaterial features and diverse potent applications of PHAs with diverse alkyl groups. Furthermore, the prospective life cycle analysis (LCA) approach was employed as a forward-looking tool, using simulation to align and standardize the methodological framework. This revealed a the true potential of the bioprocess when implemented at a pilot scale utilising the full potential of the equipment. The simulation resulted in a 73% reduction in global warming potential along with significant improvements in human health and ecosystem impacts. These findings underscore the potential of the strain for scalable, sustainable bioplastic production, offering an eco-friendly alternative to traditional plastics.