Metabolic profiling of intracellular mclpolyhyroxyalkanoate degradation in Pseudomonas aureofaciens with GC-MS

Polyhydroxyalkanoates (PHA) are biopolymers and stored in the cell in granular form as energy reserve by bacteria under stress conditions such as the limited nitrogen and excessive carbon sources. These biopolymers are alternative to petroleum-derived polymers because they have different physical and chemical properties. Also they are biocompatible and biodegradable so PHAs can be used in most of biomedical applications including tissue engineering as a tissue scaffold, controlled drug release and biomedical implants. There are lots of ungoing studies about their production and applications. These investigations are focused on increasing production yields and defining the potential applications. However, producing microorganisms are also capable to degrade polyhdroxyalkanoates. Enzymes called as intracellular PHA depolymerases carry out this process. PHA production yield can be increased by increasing PHA synthesis and by decreasing of PHA degradation rate or blocking the degradation metabolism. This process also provides reducing the cost of production and minimizing of production time. Although the recent literature gives information about extracellular PHA degradation, there is not enough knowledge about determination of intracellular degradation pathways. In this study, Pseudomonas aureofaciens was used as PHA producer organism. Octanoic acid was used as carbon source and mcl-PHA metabolism was investigated in three different metabolic conditions. Fatty acid based metabolites were analysed with GC-MS in induced PHA producing, starving and non-induce PHA producing conditions and PHA profiles were obtained. As a result of analysis, it was found that 3-hydroxyoctanoate, trans/cis-3-octenoic acid and 2-octenoic acid are directly related with poly-3-hydroxyoktanoate (PHO) metabolism and biosynthesis and degradation of polymer are occured due to these metabolites. Furthermore, it was suggested that, the other metabolites are further transformation products of the main metabolites or common metabolites of organism. According to these results, this project will provide basic knowledge about PHO metabolism.