| Abstract: | Cultures of the marine pseudomonad UP-2 growing on n-tetracosane contained both free cells and cells bound to the solid hydrocarbon. After separation by filtration through a Whatman no. 1 filter, the numbers of free and bound cells were estimated from the amount of 32P incorporated into each fraction and the determined value of 32P incorporation per viable cell in the filtrate (free cells). During the early exponential growth phase, over 80% of the cells were bound to large pieces of n-tetracosane; as the culture approached the stationary phase, the number of bound cells remained constant, whereas free cells continued to accumulate. Pulse-labeling experiments indicated that cells grew both on the surface of the solid and in the aqueous medium. During the growth cycle, a portion of the n-tetracosane which was initially nonfilterable was recovered in the filtrate in a form which was largely cell associated. This cell-associated n-tetracosane was preferentially utilized and could completely account for the observed growth of free cells. |
