The Survival of Marine Bacteria under Starvation Conditions

The survival under starvation conditions of two selected strains of marine bacteria, a yellow Pseudomonas sp. (strain 95A) and an unidentified oxidative peritrichate Gram negative rod (strain 41), was investigated. The 50% survival times of suspensions in phosphate buffer depended on cell density and were often more than 20 d. A capacity to scavenge atmospheric nitrogenous compounds led to a marked increase in the viability of cell suspensions of 10 4 cells/ml. Intracellular poly‐β‐hydroxybutyrate (PHB) prolonged the survival of strain 95A. Strain 41 contained more intracellular protein and this was degraded during starvation in ammonia‐free air. Prolonged survival was not explicable in terms of low adenylate charge states. The ‘maintenance energy’requirements of strains 95A and 41 in chemostat cultures were 0.042 and 0.04 g glucose/g dry wt/h respectively, compared with dilution‐rate‐dependent values of 0.051 to 0.856 for Escherichia coli. The low maintenance energy requirements would not alone explain the long viability. Thus no peculiar physiological property such as nitrogen‐scavenging, ability to survive at the expense of intracellular PHB or protein, abnormally low cellular protein content, low maintenance energy requirements or a low adenylate charge state fully account for the starvation resistance of these marine bacteria.