Fig. 5

Testing of transformed strains under micro-oxic conditions. a Screening assay using an adaptive laboratory evolution method with oxygen gradients. Recombinant strains were passed three times over oxygen gradients to adapt the strains to micro-oxic conditions in LB medium. b Ingrowth in oxygen gradients over consecutive rounds. The first adaptation round was monitored over 2 days, followed by two 4-day cycles. Strain performance of P. putida KT2440 pS2213−, KT2440 pS2213 ackA, KT2440 pS2213 nrdD-nrdG and KT2440 pS2213 ackA-(pyrK-pyrD B)-(nrdD-nrdG) throughout the experiment was monitored continuously with a time-lapse camera set-up, and was depicted as ingrowth in mm from the surface of the growth medium down. Above the purple dashed line the oxygen concentration is \(<0.01\) mg/l. Non-inoculated medium was taken as control. c The average progression of the recombinant strains in the oxygen gradients over time, depicted in mm/day