Fermentative production polyhydroxyalkanoates

Lee, S. Y. Park, S. J. 2005. Biosynthesis and fermentative production of SCL and MCL polyhydroxyalkanoates (SCL-MCL-PHAs). Biopolymers Online, Part 3a. 

Very recently, lactones have received increasing attention as potential renewable platform chemicals. Perhaps the most prominent bio-based hydroxy fatty acids lactic acid, whose cyclic ester of two lactate molecules serves precursor for the synthesis of bio-based polymers. Fermentative production of hydroxyl-carboxylic acids from agro-industrial waste is an alternative to the synthesis from dwindling fossil resources (Fiichtenbusch et al. 2000). The enzymatic machinery for the production of polyhydroxyalkanoates (PHA) in bacteria offers catalytic pathways for the production of these lactone precursors (Efe et al. 2008). Recent examples include the microbial synthesis of y-butyrolactone and y-valerolactone. Particularly y-valerolactone is of importance and ranks among the top key components of the biomass-based economy. Microbial processes thus offer the perspective of a sustainable fermentative production of optically pure renewable lactones. 

Lee, S. Y., Choi, J., and Wong, H. H. 1999b. Recent advances in polyhydroxyalkanoate production by bacterial fermentation mini-review. Int. J. Bio. Macromol., 25, 31-36. 

An additional advantage of the polyhydroxyalkanoates is that the polymers can be produced by fermentation. Certain types of bacteria produce PHAs for energy storage when they are grown in glucose solution in the absence of specific nutrients. The polymer forms as discrete granules within the bacterial cell, and it is then removed by extraction to give a white powder that can be melted and modified into a variety of different products. 

Polymers derived from renewable resources (biopolymers) are broadly classified according to the method of production (1) Polymers directly extracted/ removed from natural materials (mainly plants) (e.g. polysaccharides such as starch and cellulose and proteins such as casein and wheat gluten), (2) polymers produced by "classical" chemical synthesis from renewable bio-derived monomers [e.g. poly(lactic acid), poly(glycolic acid) and their biopolyesters polymerized from lactic/glycolic acid monomers, which are produced by fermentation of carbohydrate feedstock] and (3) polymers produced by microorganisms or genetically transformed bacteria [e.g. the polyhydroxyalkanoates, mainly poly(hydroxybutyrates) and copolymers of hydroxybutyrate (HB) and hydroxyvalerate (HV)] [4]. 

Abstract Polyhydroxyalkanoate (PHA) is a plastic-like material synthesized by many bacteria. PHA serves as an energy and carbon storage componnd for the bacteria. PHA can be extracted and purified from the bacterial cells and the resulting product resembles some commodity plastics such as polypropylene. Because PHA is a microbial product, there are natural enzymes that can degrade and decompose PHA. Therefore, PHA is an attractive material that can be developed as a bio-based and biodegradable plastic. In addition, PHA is also known to be biocompatible and can be used in medical devices and also as bioresorbable tissue engineering scaffolds. In this chapter, a brief introduction about PHA and the fermentation feedstock for its production are given. 

Abstract Many types of fermentation feedstock have been studied for the production of polyhydroxyalkanoate (PHA). Several industrial-scale processes have been developed for PHA production from sugars. Sugars are attractive feedstock because of their abundant supply worldwide, market stability, and also because the metabolism of PHA from sugars is very well understood. Recently, plant oils have been gaining much interest as a potential feedstock for PHA production. Industrial-scale processes for the production of PHA from plant oils are currently being developed. This chapter looks at the challenges in using plant oils, especially pahn oil as feedstock for PHA production. 

Abstract Polyhydroxyalkanoate (PHA) initially received serious attention as a possible substitute for petrochemical-based plastics because of the anticipated shortage in the supply of petroleum. Since then, PHA has remained as an interesting material to both the academia and indusby. Now, we know more about this microbial storage polyester and have developed efficient fermentation systems for the large-scale production of PHA. Besides sugars, plant oils will become one of the important feedstock for the industrial-scale production of PHA. In addition, PHA will find new apphcations in various areas. This chapter summarizes the future prospects and the importance of developing a sustainable production system for PHA. 

Bengtsson S, Pisco AR, Reis MAM, Lemos PC (2010) Production of polyhydroxyalkanoates from fermented sugar cane molasses by a mixed culture enriched in glycogen accumulating organisms. J Biotechnol 145 253-263... 

CastQho LR, MitcheU DA, Freire DMG (2009) Production of polyhydroxyalkanoates (PHAs) from waste materials and by-products by submerged and solid-state fermentation. Bioresour Technol 100 5996-6009... 

Choi J, Lee SY (1999) Eactors affecting the economics of polyhydroxyalkanoate production by bacterial fermentation. Appl Microbiol Biotechnol 51 13-21... 

Lee SY, Choi JI (1998) Effect of fermentation performance on the economics of poly(3-hydroxy-butyrate) production by Alcaligenes latus. Polym Degrad Stab 59 387-393 Lee SY, Choi J, Wong HH (1999) Recent advances in polyhydroxyalkanoate production by bacterial fermentation mini-review. Int J Biol Macromol 25 31-36 Lee SY, Lee KM, Chan HN, Steinbiichel A (1994) Comparison of recombinant Escherichia coli strains for synthesis and accumulation of poly(3-hydroxybutyric acid) and morphological changes. Biotechnol Bioeng 44 1337-1347... 

Conversion of grass biomass into fermentable sugars and its utilization for medium chain length polyhydroxyalkanoate (mcl-PHA) production by Pseudomonas strains. Bioresour. Technol, 150, 202 - 209. 

Sun Z, Ramsay JA, Guay M, Rtunsay BA (lOCfl) Fermentation process development for the production of medium-chain-length poly-3-hydroxyalkanoates. Appl Microbiol Biotechnol 75 475-485 Suriyamongkol P, Weselake R, Narine S, Moloney M, Shah S (2(X)7) Biotechnological approaches for the production of polyhydroxyalkanoates in microoigtmisms and plants - a review. Biotechnol Adv 25 148—175... 

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