Long term starvation of a marine bacterium,Alteromonas denitrificans, isolated from a Norwegian fjord

The marine bacterium Alteromonas denitrificans has survived for up to 7 years in unsupplemented sea water. The relatively low affinities for uptake of arginine and glucose (Kt of 80 and 790 μM, respectively) indicate that A. denitrificans takes up substrates effectively only at high concentrations. This bacterium was starved in artificial seawater alone, with nutrients (ammonium and phosphate) or with energy (glucose or arginine) added. Incorporation of thymidine into DNA decreased rapidly upon starvation, indicating a cessation of DNA synthesis. At the onset of starvation the number of colony-forming units (c.f.u.) increased 3-fold while the cell volume decreased by one-third except in the presence of glucose where the c.f.u. decreased and the volume increased 4-fold. Cells starved in the presence of glucose had a lower viability during most of the starvation period than cells starved in artificial sea water alone, while cells starved in the presence of arginine had a higher viability. Variations in the content of protein, carbon and nitrogen, in c.f.u. and in the uptake of arginine throughout a 30-day period indicate that A. denitrificans does not rapidly adapt to starvation but undergoes a series of cellular alterations.