Polyhydroxyalkanoates: advances in the synthesis of sustainable bio-plastics

The extensive use of petro-based plastics, lack of suitable waste management and casual behaviour of communities to their proper disposal has posed a significant threat to the environment. Currently, single-use petro-based plastics are being banned all over the world due to their inherent non-degradability and problems with disposal. Worldwide, these bans have proved an impetus for increasing research on bio-based polymers as a substitute for conventional plastics. Use of greener or biodegradable polymeric materials would have immense socio-economic and ecological significance. Polyhydroxyalkanoates (PHAs) are eco-friendly alternatives to petrochemical plastics and are quickly biodegraded in aerobic or anaerobic environments such as a landfill, waste treatment facilities or oceans. PHAs have material and mechanical properties ranging from stiff and brittle crystalline to elastomeric and moulding, similar to petrochemical thermoplastics. In addition, they are hydrophobic, isotactic, biocompatible and have piezoelectric properties. PHAs in being environmentally friendly are seen as ideal candidates for replacing conventional petro-based plastics in numerous fields. This review focuses on the biochemistry along with in-vitro reaction mechanism of PHA synthases. In addition to the applications and modes of production of PHAs already mentioned a few factors governing PHA synthesis will be discussed. Scope for improving PHA synthesis is also mentioned and some of the tools for enhancing the properties of PHAs are discussed.