Bacterial bioplastics

Witholt, B., Kessler, B. Perspectives of medium chain length poly(hydroxyalkanoates), a versatile set of bacterial bioplastics. Cutr. Opin. Biotechnol. 10, 279-285 (1999)... 

Singh, S. and Mohanty A.K. (2007) Wood fiber reinforced bacterial bioplastic composites Fabrication and performance evaluation. Compos. Sci. Technol., 67, 1753-1763. 

Chapters cover nearly every conceivable topic related to polysaccharides, such as biofibers, bioplastics, biocomposites, natural rubbers, proteins, gums, and bacterial polymers. Given the global context it does not seem preposterous to consider the materials discussed as the polymers of the future. 

A new family of bacterial biopolymers (thioester-containing PHAs) was reported by Lutke-Eversloh et al. (2001a, b). These authors showed that C. necator was able to synthesize and polymerize (R)-3-mercaptopropionic acid, thus generating a novel type of PHA that contains sulphur in the polymer backbone. Whereas in other PHAs the monomers are covalently linked by oxoester bonds, in these bioplastics they are linked by thioester bonds. For this reason, these polymers are referred to as polythioesters (Lutke-Eversloh et al. 2001a, b). 

Also a bacterial pathway for the synthesis of PHB by R. eutropha HI 6 into the diatom Phaeodactylum tricomutum has been described. The PHB production is feasible in a microalgal system. There, the bioplastic accumulates in granule-like structures in the cytosol of the cells, as shown by light and electron microscopy (13). 

A biopolymer or bioplastic is a polymer produced by a living organism. Cellulose is the most common biopolymer constituting about a third of all plant biomass. All living things produce other biopolymers such as polynucleotides and proteins. An example of a class of useful biopolymers are the so-called bacterial polyesters that are harvested from bacteria grown under specific conditions. 

Poly(Hydroxyalkanoates) Unlike bio-based PE, PET, and PEA, the poly(hydroxyalkanoates) (PHA) are bioplastics synthesized by bacteria. It was the first bacterial polymer to be harvested commercially. PHAs are deposited within the bacterial cells of many species as a lipoic material (Bnrdon, 1946). It is also unusual in that PHAs though hydrophobic still rapidly biodegrade in the environment. All bacterial polymers are not necessarily biodegradable (Steinbuchel, 2005) PHAs biodegradability is attributed to its saturated polyester chemical structure. 

PHA applications as bioplastics, fine chemicals, implant biomaterials, medicines, and biofuels have been researched for many years. Bacterial PHA synthesis has been found... 

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