Modern Biotechnological Polymer Synthesis: A Review

Martin Koller^1*, Anna Salerno^1,2, Miguel Dias¹, Angelika Reiterer¹ and Gerhart Braunegg<sup>1

1</sup>Research group Applied Physiology, Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 12, AT-8010 Graz, Austria
²Department of Environmental Sciences, Parthenope University of Naples, Centro Direzionale, Isola C4, IT-80143 Naples, Italy

Article history:
Received November 23, 2009
Accepted May 21, 2010

Key words:
biopolymers, downstream processing, fermentation strategy, polyhydroxyalkanoates, process design, raw materials, white biotechnology

Summary:
The industrial implementation of cost- and eco-efficient production of bio-based polymeric materials such as polyhydroxyalkanoates (PHAs) or polylactic acid (PLA) requires the comprehension of all process steps. The article at hand provides an insight into recent advances in allocation, pretreatment and utilization of raw materials available for biopolymer production in different areas of the world. Further, the high potential and risks of applying continuous process conduction in comparison with batch and fed-batch fermentation mode are elucidated. It is shown that the process design for continuous PHA production strongly depends on the kinetic characteristics for growth and product formation of the applied production strain. In addition, the triggering of the biopolymer properties by fine-tuning of the polyester composition during biosynthesis is demonstrated. Here, the impact of certain process parameters like the partial oxygen tension on the intracellular metabolic fluxes and the supplementation of cosubstrates on the polyester composition are discussed. In addition, such specialists among microbes are presented that possess the metabolic prerequisites to accumulate high-quality copolyesters merely from cheap unrelated carbon sources without the necessity for supplying expensive cosubstrates. In the field of downstream processing, sustainable methods for product isolation during biopolymer production that do not have a negative influence on the environment are presented.

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