Sequential utilization of substrates by Pseudomonas putida CSV86: signatures of intermediate metabolites and online measurements

Pseudomonas putida CSV86 preferentially utilizes aromatics over glucose and co-metabolizes them with organic acids. On aromatics plus glucose, CSV86 utilized aromatics first with concomitant appearance of transient metabolites such as salicylate, benzaldehyde and benzoate. Citrate was the main extracellular metabolite observed during glucose uptake. The strain showed simultaneous utilization of organic acids and aromatic compounds. Based on the metabolite analysis and growth profiles, we hypothesize that the repression of glucose utilization could be due to organic acid intermediates generated from aromatic compound metabolism. The online measurements indicate the instantaneous metabolic state of the culture. For example, the CO₂ evolution and agitation speed show peak values during the two growth phases in the diauxic growth while dissolved oxygen values show decrease at the corresponding durations. These measurements correlated well with the offline measurements but provided a better time resolution of the process.