Conversion of Biomass into Bioplastics and Their Potential Environmental Impacts

To build our economy on a sustainable basis, we need to find a replacement for fossil carbon as chemical industry feedstocks (Andrady and Neal, 2009). There are growing concerns about current petroleum based production, accumulation of waste in landfills and in natural habitats including the sea, physical problems for wildlife resulting from ingestion or entanglement in plastic, the leaching of chemicals from plastic products and the potential for plastics to transfer chemicals to wildlife and humans (Thompson et al., 2009). Bioplastics, derived from bio-based polymers, may provide a solution. Unlike the chemically synthesized polymers, the bio-based polymers are produced by living organisms, such as plants, fungi or bacteria. Some microorganisms are particularly capable in converting biomass into biopolymers while employing a set of catalytic enzymes. Attempts to transfer biomass to produce industrially useful polymers by traditional biotechnological approaches have obtained only very limited success, suggesting that an effective biomass-conversion requires the synergistic action of complex networks. As an interdisciplinary research field which is a unique combination of life science and engineering, synthetic biology can provide new approaches to redesign biosynthesis pathways for the synergistic actions of biomassconversion and may ultimately lead to cheap and effective processes for conversion of biomass into useful products such as biopolymers. In the following sections of this review, we will give first an introduction on bioplastics and synthetic biology (section 2). The properties of bio-based polymers for bioplastics equal to or better than their chemical synthetic counter parts will be compared. The subfields of synthetic biology related to polymer biosynthesis will be reviewed. In the Section 3, we will focus on synthetic biological approaches to improve the biological system to produce polymers for bioplastics, such as polyhydroxyalkanoates (PHAs). The fourth section then goes on to evaluate the environmental impacts of the synthetic biology derived bioplastics. In this section, we will review the current methods to measure the environmental impacts on bioplastics on greenhouse gases (GHGs) emission, direct or indiret land usage, energy consumptions and waste management, as well as the current regulation guidelines on bioplastics in Europe. And in the last section, we will summarize the perspectives of synthetic biology and bioplastics.