Intra- and extra-cellular organophosphorus hydrolase production with recombinant E. coli using fed-batch fermentation

A fed-batch fermentation process for the production of organophosphorus hydrolase (OPH) (EC 3.1.8.1) by E. coli pET812 was developed in this research. With batch fermentation, the maximum OPH concentrations attained by batch fermentation were as low as 4 x 10⁵ U/l because cell growth and OPH production were inhibited by a high initial concentration of glucose. To develop a fed-batch fermentation process for obtaining higher concentrations of OPH, highly concentrated glucose solution (500 g/l) was added intermittently or continuously to increase the carbon source concentration. Eventually, 3.2 x 10⁶ U/l of OPH was produced with fed-batch fermentation in 24 h. This was eight times higher than the yield with conventional batch fermentation. A total concentration of 399-441 mg of OPH was produced/l, which was four times higher than that reported when using E. coli. Nearly half (44%) of the produced OPH was secreted into the culture solution.