AbstractsBiology & Animal Science

Vibrio marinus MP-1 (ATCC 15381) deaminated nine of seventeen amino acids tested with L-glutamine being deaminated to the greatest and L-serine to the second greatest extent in one hour. The optimum pH for the L-serine deamination was 8.4. The response of washed cells to temperature on the deamination of L-serine depended upon the growth temperature of V. marinus MP-1. Cells grown at 15 C had an optimum of deamination activity at 40 C, and a shoulder at 15 C, while 4 C grown cells had greatest activity at 38 and 11 C. It is suggested that these peaks in deamination of L-serine at different temperatures might be due to several different enzymes deaminating the amino acid or the result of loss of permeability control above the maximum growth temperature of the organism. Hydrostatic pressure stimulated or suppressed L-serine deamination by washed cells depending upon the temperature at which the cells were grown and the incubation temperature of the reaction mixture. Cells grown at 15 and 4 C had deamination stimulated under hydrostatic pressure in the following cases: (1) cells grown at 15 C and tested for deamination at 15 C, (2) cells grown at 4 C and tested at 4 C and (3) cells grown at 4 C and tested at 15 C. When cells were grown at 15 C and tested at 4 C no stimulation of deamination activity due to hydrostatic pressure was observed. These results adequately show that a very important part of the nitrogen cycle, the deamination of an amino acid by a marine bacterium, can occur in the ocean down to hydrostatic pressures of 400 atm and at temperatures below 20 C.