Microbial Production of Biopolymers and Polymer Precursors

Abstract

Abstract: Living organisms, namely, prokaryotes and eukaryotes, are able to synthesize a variety of polymers, such as nucleic acids, proteins, and other polyamides, polysaccharides, polyesters, polythioesters, polyanhydrides, polyisoprenoids, and lignin. Microorganisms provide a source of biopolymers and biopolysaccharides from renewable sources. Bacteria are capable of yielding biopolymers with properties comparable to plastics derived from petrochemicals, though more expensive. They have the additional advantage of being biodegradable. A wide range of microbial polysaccharides have been studied, and structure/function relationships for a number of these macromolecules have been determined. These biopolymers accomplish different essential and beneficial functions for the organisms. Among the biopolymers produced, many are used for various industrial applications. Currently, the biotechnological production of polymers has been mostly achieved by fermentation of microorganisms in stirred bioreactors. The biopolymers can be obtained as extracellular or intracellular compounds. Alternatively, biopolymers can also be produced by in vitro enzymatic processes. However, the largest amounts of biopolymers are still extracted from plant and animal sources. Biopolymers exhibit fascinating properties and play a major role in the food processing industry, e.g., modifying texture and other properties. Among the various biopolymers, polysaccharides and bioplastics are the most important in the food industry. This chapter will discuss the sources of polymers, their biosynthesis by different organisms, and their application in different fields. A huge variety of biopolymers, such as polysaccharides, polyesters, and polyamides, are naturally produced by microorganisms. These range from viscous solutions to plastics and their physical properties are dependent on the composition and molecular weight of the polymer. The genetic manipulation of microorganisms opens up an enormous potential for the biotechnological production of biopolymers with tailored properties suitable for highvalue medical application such as tissue engineering and drug delivery.