The yield of dry biomass is approximately 5.44 g g−1 NH4 [36]. Since, the medium initially contained only 0.5 g (NH4)2SO4, there was only enough nitrogen to support 0.76 g l −1 of biomass before the N-source was exhausted. Both the wild-type P. putida KT2440 and DZ18 grew to a maximum of 2.50 g l −1 dry biomass.