Abstract
This paper reports the results of a comparison of two aquatic, psychrotrophic bacteria, with regard to growth rate, total cell yield, and total amount of labelled amino acid incorporated into protein, at temperatures within the range 0-30°. Based on growth rate constants, the optimum temperatures for growth, in BOYLEN and BROCK (1) broth, were 25° for isolate F and 30° for isolate T. For both isolates, these temperatures did not give the highest cell yields. Nevertheless, the difference between total cell yield at the optimum growth temperature and the highest total cell yield was not substantial for either isolate. The Arrhenius plots were similar with respect to slope and the absence of any deviation from linearity at the lower temperatures tested. At all of the temperatures examined within the range 0-30°, isolate T incorporated significantly more phenylalanine into protein than did isolate F. This difference in the absolute amount of amino acid incorporated into protein was obvious in all of the growth media tested. The difference could not be attributed to a difference in the protein content of the two isolates. In addition to the incorporation difference between the two isolates, each isolate showed incorporation differences as a function of temperature, and the relationship for each isolate was very different.
