(144i) Understanding and Modeling Effects of Nitrogen Source on Biosynthesis of Polyhydroxyalkanoates from Benzoate By Pseudomonas Putida KT2440

Benzoate has been widely used as a model compound for the study of bacteria catabolism of aromatic compounds. Nitrogen source is critical to the synthesis of intracellular polyhydroxyalkanoates (PHAs) in various bacteria. However, exact effects of nitrogen source in the PHAs biosynthesis process from benzoate in Psuedomonas putida is unclear. In this study, the PHAs biosynthesis process from benzoate by Pseudomonas putida KT2440 was investigated under nitrogen surplus and limit conditions. In nitrogen limit condition, PHAs accumulated up to 37.3% of its cell dry weight (CDW) and eleven types of monomers were identified through GC/MS analysis. On the contrary, PHAs only accounted for 0.25% of CDW and three main PHAs monomers were found under nitrogen surplus condition. NMR and GPC results confirmed that PHAs molecular weight started to increase when the nitrogen source exhausted while the PHAs concentration maintained at the similar level under surplus nitrogen condition. Kinetic models were developed to adequately predict the biomass growth, PHA accumulation, and benzoate consumption. Results indicated that the cell growth and PHA accumulation fit the Monod-type model and the PHA synthesis process was dependent to nitrogen exhausting condition.