Environmental and operational stresses in PHA Biosynthesis: Mechanisms, Challenges, and Sustainable Solutions

Polyhydroxyalkanoate (PHAs) is a green biomaterial that is fully degradable in the natural environment and is considered an alternative to traditional plastics. However, the high cost of production is the primary factor impeding the large-scale implementation of PHAs. The use of cheap carbon sources in the synthesis of PHAs has been demonstrated to result in a substantial reduction in production expenses. However, it is imperative to note that production efficiency is acutely susceptible to the occurrence of potential stresses. The discussion commences with an examination of the relationship between osmotic stress (i.e. endogenous potential stresses) and PHAs production, followed by an analysis of the relationship between organic loading rate (i.e. exogenous potential stresses) and PHAs production. In order to explore the regulatory mechanism of stress on PHAs production, the relationship between redox stress and PHAs synthesis/mobilisation is also discussed. Finally, the article summarises exogenous regulatory measures for different potential pressures, as well as the survival adaptation mechanisms of PHAs producers.