Abstract
Summary: Pseudomonas putida forms an inducible β-ketoadipate transport system that is expressed optimally under conditions of carbon and energy starvation. Adipate is a non-metabolizable analogue for the β-ketoadipate transport system and exposure to adipate of P. putida strains that constitutively form high levels of the transport system resulted in an extensive loss in viability during starvation. Full viability was retained when the mutants were starved in the absence of adipate, and wild-type P. putida cells survived well either in the presence or absence of adipate. A possible cause of death during starvation in the presence of adipate is depletion of energy reserves by futile cycling of adipate via the active transport system. Sensitivity of the constitutive strains to killing by adipate indicates the necessity for tight control over the expression of transport systems during bacterial starvation to ensure survival.