Enhancement of phenazine-1-carboxylic acid production using batch and fed-batch culture of gacA inactivated Pseudomonas sp. M18G

Abstract

The enhancement of phenazine-1-carboxylic acid (PCA) production was investigated in a 10 l fermentor using a gacA chromosomally inactivated mutant Pseudomonas sp. M18G combined with DO-stat feeing strategy. In batch culture, the optimal growth conditions with a two-stage agitation and aeration at 1.72vvm improved PCA production to 1987 mg/l at 48 h fermentation. A mathematical kinetic model consisting of cell growth, high PCA production, and substrate consumption was developed to simulate the batch culture process. Further increases in PCA production were achieved in a DO-stat fed-batch system which maintained a constant DO of 20% by a two-pulse glucose feeding strategy. With a total 6.6 g/l glucose feeding, the maximum PCA production of 2597 mg/l was obtained at 72 h fermentation, resulting in a 44.5% increase in PCA production and 10-fold greater cell numbers compared to the batch culture. The combination strategies might pave a new way for the phenazine derivative commercial production using various pseudomonads.