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Flux Balance Analysis for Maximizing Polyhydroxyalkanoate Production in Pseudomonas Putida

S. RAMALINGAM, VIKRAM M. P. VIGNESHBABU and M. SIVASANKARI

The work is aimed at developing process strategies to understand the behavior of P. putida for cost effective synthesis of mcl-PHA with the help of metabolic flux model developed using linear programming. With this context, screening and selection of suitable carbon sources for mcl-PHA production was done. Among the various carbon sources used for shake flask experiments, linoleic acid gave maximum product synthesis than glucose and glycerol. The higher yield in linoleic acid is not reported in literature so far. Metabolic flux analysis was done in nitrogen limited continuous cultivation of Pseudomonas putida with glucose, glycerol and linoleic acid as carbon sources. The reasons for higher PHA biosynthesis in linoleic acid can be understood by the metabolic flux analysis of continuous cultivation experiments with various carbon sources. The optimal C/N ratio was obtained by simulating with the range of carbon and nitrogen uptake rates as constraints of the metabolic flux model. The model predicted optimal C/N ratio and the same was implemented in fed batch cultivation experiments. The fed batch fermentation resulted the highest PHA synthesis with linoleum acid as carbon source. But the cost of linoleic acid is the tailback for the cost effective production of mcl-PHA. A metabolic flux model was developed for dual substrate utilization to minimize the amount of linoleic acid for optimal PHA synthesis. Atlast, the two stage fed batch fermentation strategy was implemented with glucose and linoleic acid for cost effective biosynthesis of PHA.