Effect of previous growth conditions on starvation survival and endogenous metabolism rate of Arthrobacter fluorescens

Abstract

AbstractThe starvation survival and the endogenous metabolism rate were studied in cultures of Arthrobacter fluorescens grown at various dilution rates under ammonium‐limited conditions. In addition, the ammonium‐limited cultures grown at dilution rates of 0.03 and 0.20 h−1 were made oxygen‐limited and these cultures were also studied. Suspensions of washed cells from all the steady state cultures were incubated under total nutrient deprivation at 30°C for 20 days. The effects of starvation on cell counts, protein and carbohydrate contents and endogenous respiration rates were determined. Viable cell count of suspensions grown under ammonium‐limited conditions declined faster for the cells grown at faster dilution rates. On the contrary starved slow growing oxygen‐limited cells showed a more rapid decrease in viability than the fast growing ones. Cell dry weights, carbohydrates and proteins declined exponentially during starvation and their rates of change were generally greater with cells grown at higher dilution rates, irrespective of nutrient limitation. Starved oxygen‐limited cultures exhibited a higher death rate and a greater reserve material mobilization than ammonium‐limited cultures grown at the same dilution rate.