Challenges and Opportunities for Customizing Polyhydroxyalkanoates

• Published in: Indian journal of microbiology Vol. 55; no. 3; pp. 235 - 249
• Main Authors: Singh, Mamtesh, Kumar, Prasun, Ray, Subhasree, Kalia, Vipin C
• Format: Journal Article
• Language: English
• Published: New Delhi Springer India 01.09.2015; Springer Nature B.V
• Subjects: Bacteria; biodegradability; Biodegradation; Biomedical and Life Sciences; Biopolymers; feed prices; feeding methods; genetic engineering; Genomics; glass transition temperature; Life Sciences; Mechanical properties; Medical Microbiology; Melting point; Metabolism; Microbiology; modulus of elasticity; Molecular weight; petroleum; Physicochemical properties; Physiology; plastics; Polyhydroxyalkanoates; Polyhydroxybutyrate; Polymers; production costs; Review; Review Article; tensile strength; Thermal properties; Transition temperatures; India; Bioplastic; PHA synthases; Strategies; Thermo-mechanical properties; Co-polymers
• ISSN: 0046-8991; 0973-7715
• DOI: 10.1007/s12088-015-0528-6

Polyhydroxyalkanoates (PHAs) as an alternative to synthetic plastics have been gaining increasing attention. Being natural in their origin, PHAs are completely biodegradable and eco-friendly. However, consistent efforts to exploit this biopolymer over the last few decades have not been able to pull PHAs out of their nascent stage, inspite of being the favorite of the commercial world. The major limitations are: (1) the high production cost, which is due to the high cost of the feed and (2) poor thermal and mechanical properties of polyhydroxybutyrate (PHB), the most commonly produced PHAs. PHAs have the physicochemical properties which are quite comparable to petroleum based plastics, but PHB being homopolymers are quite brittle, less elastic and have thermal properties which are not suitable for processing them into sturdy products. These properties, including melting point (Tₘ), glass transition temperature (Tg), elastic modulus, tensile strength, elongation etc. can be improved by varying the monomeric composition and molecular weight. These enhanced characteristics can be achieved by modifications in the types of substrates, feeding strategies, culture conditions and/or genetic manipulations.