Optimization For Fermentation Conditions Of Phenazing-1-Carboxylic Acid In Genetically Engineered Bacteria M18G

Pseudomonas sp. M18 is a rhizomatic fluorescent bacterium that can produce two antibiotics, pyoluteorin (Plt) and phenazine-1-carboxylic acid (PCA). We constructed M18G, a mutant strain in gacA gene of M18, by means of homologues recombination. In King's B medium, synthesis of Plt in M18G was completely inhibited, while the accumulation of PCA was higher than that in wild type.To further increase the production of PCA by M18G, we employed the Plackett-Burman designs and the Response Surface Method to optimize the fermentation condition based on our results of single factor analysis. The obtained optimal fermentation conditions were glucose 0.87%, glycerol 0.6%, ethanol 0.8%, soybean meal 4%, peptone 0.4%, pH 6.5, liquid loading 40/250, inoculum 4%, age of inoculum. 10.3h, temperature 28℃. Under these conditions, The fermentation efficiency of PCA was increased by 472.8% compared to that in King's B medium, from 250 mg/L to 1432 mg/L.In a 10L fermenter, we found that the best condition for PCA synthesis was with Stirring speed at 230 r/min and ventilation of 1.67 vvm. At this condition, the maximum cell volume and PCA production were 12.89 and 1407 mg/L, respectively. In addition, we tested different methods to supply 10% glucose into medium after 24 hours'fermentation. Our data indicated that supply by 40ml/L constant flow generated...