Influence of oxygen levels on a genome reduced Pseudomonas putida strain

The bacterium Pseudomonas putida is becoming a cell factory of choice due to its versatile metabolism and high stress tolerance, the latter being of prime importance when considering production at large scale and bioconversion of potentially toxic chemicals. These phenotypic features have led to the development of P. putida as a platform organism including the development of genome reduced chassis strains like the SEM10 [1]. However, thorough characterization of the genome-reduced strain under industrially relevant conditions is still lacking. In order to compare the wild type KT2440 with the genome reduced SEM10 we cultivated both strains under varied oxygen levels. The oxygen levels were varied by changing the partial pressure of oxygen in the cultivation gas, thereby reducing the influence of shear. SEM10 showed better growth properties compared to the wild type during cultivation with the pO2 equal to ambient air. The wild type KT2440 strain accumulated 3.84±0.06 g/L CDW compared to 4.42±0.23 g/L CDW by SEM10 under conditions of ambient air. When cultivated under a partial pressure of oxygen equal to 25% of ambient air, SEM10 accumulated 4.56±0.23 g/L CDW compared to 3.64±0.28 g/K CDW by KT2440 within the same time span. The ability of SEM10 to accumulate more biomass during conditions of both ambient and low partial pressure of oxygen suggests that the genome reduced strain is able to retain its superior growth properties even at poor oxygen availability.