EFFECT OF CERTAIN VARIATIONS IN DILUENT AND DILUTION PROCEDURE ON SURVIVAL OF PSEUDOMONAS SPECIES GROWN IN VARIOUS MEDIA1

Abstract

Studies on the effect of various diluents on the level of population of pseudomonads grown in skimmilk, nutrient broth, and on agar slants indicate that with skimmilk cultures usually minor increases or decreases in viable counts occurred. With cultures grown in nutrient broth at 25 C, reductions in numbers after holding in phosphate buffered water or distilled water became more prevalent. The viable population of cell suspensions from agar-slant cultures held in either Standard Methods buffer or distilled water decreased rapidly in most instances. The temperature of the diluent did not have a significant effect on the survival of test cultures in various diluents. Studies on the effect of cell concentration on survival of test cultures in various diluents indicate that in general only minor changes in viable count could be attributed to differences in cell concentration. With respect to pH of the diluting fluid, a diluent at pH 7.0 seemed preferable. Experiments with distilled waters from difference sources indicate that the type of water used as diluent can have a great effect on the viable count.