Polyhydroxyalkanoates carbon sources

Various procaryotic microorganisms can produce polyhydroxyalkanoates using regenerable carbon sources. This polymer is a storage material and can make up to 90 % of the dried cell weight. The most widely researched material in this group up till now is the poly-D(-)-3-hydroxybutyric acid (PHB). 

Philip S, Keshavarz T, Roy I (2007) Polyhydroxyalkanoates biodegradable polymers with a range of applications. J Chem Technol Biotechnol 82 233-247 Pierce L, Schroth MN (1994) Detection of pseudomonas colonies that accumulate poly-beta-hydroxybutyrate on Nile blue medium. Plant Dis 78 683-685 Pijuan M, Casas C, Baeza JA (2009) Polyhydroxyalkanoate synthesis using different carbon sources by two enhanced biological phosphorus removal microbial communities. Process Biochem 44 97-105... 

Wang, Q. and Nomura, C.T. (2010) Monitoring differences in gene expression levels and polyhydroxyalkanoate (PHA) production in Pseudomonas putida KT2440 grown on different carbon sources. /. Biosci. Bioeng., 110 (6), 653 -659,... 

Valappil, S., Peiris, D., Langley, G., Hemiman, J., Boccaccini, A., Bucke, C., Roy, I. Polyhydroxyalkanoates (PHA) biosynthesis from stracturally unrelated carbon sources by a newly characterised Bacillus spp. J. Biotechnol. 127, 475 87 (2007)... 

Total amounts of accumulated polyhydroxyalkanoates are rather low but could probably be improved by adjusting medium composition. In shaking flask experiments this strain is known to accumulate approximately SO to 60 % PHA of cell dry weight with glucose and lactose as carbon sources respectively . 

Many bacteria can use glycerol as a carbon source. As it is a by-product of the production of bio-diesel it can be achieved chet ly. Therefore it seems to be a good alternative to glucose for die production of Polyhydroxyalkanoates. Sodiumvalerate is often used as a precursor in order to obtain the copolymer Poly-3-hydroxybutyrate-co-3-hydroxyvalerate. As Biorelated Potymers Sustainable Polymer Science and Technology Edited by Chiellini et al., Kluwer Academic/Plenum Publishers, 2001 147... 

Polyhydroxyalkanoate synthases can use many different substrates and the number of viable pathways for the biosynthesis of PHAs is huge. When new substrates are used, novel PHAs can be produced. In aiming to reduce production costs, it will be useful to search for bacteria that can synthesize precursor substrates from simple and cheap carbon sources [36,92]. It has also been revealed that, when a PHA synthase enzyme is expressed in a different host microbe, it may result in different substrate speciflcity and therefore new PHAs with new chemical and physical properties are accessible [11]. 

Abstract Polyhydroxyalkanoates (PHAs) are natural polyesters that accumulate in numerous microorganisms as a carbon- and energy-storage material under the nutrient-limiting condition in the presence of an excess carbon source. PHAs are considered to be one of the potential alternatives to petrochemically derived plastics owing to their versatile material properties. Over the past few decades, extensive detailed biochemical, molecular-biological, and metabolic studies related to PHA... 

Pozo C, Martlnez-Toledo MV, Rodelas B, Gonzales-Lopez J (2(X)2) Effects of culture conditions on the production of polyhydroxyalkanoates by Azotobacter chroococcum H23 in media containing a high concnetration of alpechin (wastewater from olive oil mills) as primary carbon source. J Biotechnol 97 125-131... 

Wang Q, Zhuang Q, Liang Q, Qi Q. Polyhydroxyalkanoic acids from structuraUy-unrelated carbon sources in Escherichia coli.Appl Microbiol Biotechnol 2013 97 3301-7. 

Tsuge T. Metabolic improvements and use of inexpensive carbon sources in microbial production of polyhydroxyalkanoates.J Biosci Bioeng 2002 94 579-84. 

Biotechnology continues to be an important contributor to the biorefinery, especially for the conversion of carbohydrates. The paper by Richard describes a new approach for the fermentation of C sugars, providing methodology for more efficient conversion of biomass carbohydrates to EtOH. The contribution from Nakas discusses the bioproduction of polyhydroxyalkanoates using levulinic acid as a carbon source. Stipanovic describes new approaches for using hemicellulose as a chemical feedstock. 

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