Genetic algorithm-based medium optimization for enhanced production of fluorescent pseudomonad R81 and siderophore

Fluorescent pseudomonad R81, a root-colonizing bacterium, is a potential bio-inoculant due to its plant growth promoting characteristics. It produces hydroxamate-type siderophore which is involved in disease suppression in plants. Genetic algorithm (GA) methodology was applied for the optimization of siderophore and cell mass production simultaneously in shake flask experiments. A total of 10 medium components were optimized within 80 experiments. A high siderophore concentration of 1.9 g/L and cell mass concentration of 2.8 g/L was achieved in the optimized medium. The application of GA was well suited for determination of optimum concentration levels of the medium constituents for a bi-objective function. GA was able to increase the siderophore concentration by 2.8-fold when compared to RSM-based optimization. Further, the batch fermentation of the GA-optimized medium in 14 L bioreactor without pH control produced 2.2 g/L siderophore in 36 h, the highest reported so far. GA was also successfully used to estimate the kinetic parameters of the mathematical models of the batch fermentation.