Bioplastics: A sustainable approach toward healthier environment

Abstract

An uncontrolled usage of conventional nonbiodegradable plastics over a long period of time has resulted in large-scale accumulation of waste and release of greenhouse gases in the environment, thus giving rise to severe environmental problems. More recently, a widespread global concern toward these environmental issues has provided a major impetus to the search for suitable biodegradable substitutes which may have minimal side effects on the environment, but still retain the properties and the ability to be used in applications similar to the existing conventional synthetic polymers. Biodegradable plastics or bioplastics may be defined as polymers which can be completely converted by living organisms, usually microorganisms, to carbon dioxide, water, and humic material. Among the various biopolymers produced by microorganisms, polyhydroxyalkanoates (PHAs) have generated a specific interest among the biotechnologists because of their thermoplastic characteristics and resemblance to synthetic polymers to a large extent, thus holding a potential for replacing conventional nonbiodegradable plastics. Two forms of PHA, that is, polyhydroxybutyrate (PHB) homopolymer and 3HB-3HV (-3-hydroxybutyrate-3-hydroxyvalerate) copolymer, are popularly used for commercial production of bioplastics. However, PHB is the best characterized form of PHA, found to be produced naturally by several microorganisms as energy storage molecule in response to stressful conditions. The present review highlights several aspects of these potential biopolymers including their history, basic structure and properties, genetic background of their biosynthesis, and finally their applications in different areas.