Recombinant strains expressing oxalate decarboxylase efficiently and environmental characteristics of their life cycle assessment

Abstract

Oxalate decarboxylase has garnered significant attention due to its wide-ranging applications, particularly as an effective demulsifier for oil pollution remediation. However, the accumulation of oxalate decarboxylase by strain is insufficient, and the acquisition of necessary nutrients and energy for biosynthesis also poses challenges to the environment. Therefore, it is crucial to assess the strain's capacity and environmental burden in order to guide future developments and ensure sustainable scale-up. To enhance the protein yield of oxalate decarboxylase from Bacillus mojavensis XH1 (Bacm OxdC), a specialized biodemulsifier, our study investigated the properties of Bacm OxdC and improved its expression efficacy in Escherichia coli from an environmentally friendly perspective. By employing a promoter tandem strategy and optimizing the 5′ untranslated region, recombinant strains C3 and C5 were constructed, resulting in 1.22-fold and 6.90-fold increases in Bacm OxdC expression levels compared to the initial strain C1. The bioprocess of strain C5 achieved a life cycle assessment (LCA)-based environmental impact value of 322.75, representing the lowest environmental impact observed thus far. Improvement strategies included reducing protein purification steps and electricity consumption, which can further mitigate negative environmental impacts and carbon emissions. This study offers a technical strategy for large-scale production of oxalate decarboxylase while attaining green and low-carbon objectives for biological demulsifiers.