Figure 4

Co-cultivation experiments using various Pseudomonas strains assessing growth on extracellular glycerolphosphorylcholine (GPC) (100 μM), the potential GPC cleavage product glycerol 3-phosphate (G3P), phosphocholine (Pch), as well as growth on orthophosphate (Pi). Either P. stutzeri DSM4166 (block red) or P. fluorescens SBW25 (hashed red) were used as the GPC utiliser. All blue bars indicate when a strain was the proposed beneficiary of GPC catabolism. Growth was determined by calculating the number of generations based on plate counts for each strain in the co-cultivation experiment. Asterisks represent conditions where the non-GPC degrader did not grow or when growth of a given mutant was significantly reduced compared to the wild type (T-Test P < 0.05). (A) Growth of the ΔglpQ mutant in the presence of the parental wild type (WT) strain revealed that the mutants could still grow despite lacking the ability to degrade GPC (Upper and Middle Panel). Note that the P. stutzeri DSM4166 ΔphoBR mutant (lower panel) showed a severe fitness defect (due to loss of expression of the high affinity Pi transporter). (B) Both the wild type and ΔglpQ mutants for P. stutzeri DSM4166 and P. fluorescens SBW25 were co-cultivated with P. putida BIRD-1 on either Pi or GPC. (C) P. stutzeri DSM4166 and P. fluorescens SBW25 were co-cultivated with various P. putida BIRD-1 mutants (ΔphoX and ΔphoBR). Again, the BIRD-1 ΔphoBR mutant does not express the high-affinity Pi transporter. Results shown are the mean of triplicate cultures. Error bars denote standard deviation.