The stimulation or inhibition of growth and acid precipitable material production of Vibrio Fetus by Kreb's cycle intermediates, fatty acids, amines, and miscellaneous compounds

Abstract

Using the chemically defined medium designed by Smibert (1963), the stimulatory or inhibitory effect of test compounds on the growth and the production of acid precipitable material by seven strains of vibrio fetus was determined. The test compounds were Krebs cycle intermediates, lactate, pyruvate, fatty acid, amines, surface active agents, aminobutyrate, hydroxybutyrate, glutathione, asparagine, phenylacetyl chloride, and sodium bicarbonate. Experimental media consisted of the chemically defined medium containing various concentrations of the test compounds. An exact number of cells of each strain of V. fetus was inoculated into tubes of experimental broth media. The cultures were incubated at 37 °C in desiccator jars in an atmosphere containing 85% nitrogen, 10% carbon dioxide, and 5% oxygen. Cultures were observed daily for visible growth. After five days incubation, the optical density of each culture was read at 5/+0 mμ; in a spectrophotometer. The concentration of APM produced by each strain of V. fetus grown in experimental media was also determined. Five day old cultures of each strain were centrifuged, and the APM present in the supernatant fluid was precipitated with trichloroacetic acid. The optical density of the mixture was read at 380 mμ, in the spectrophotometer. Lactate increased the growth of four of five strains of V. fetus tested, and did not inhibit the growth of any strains. Lactate increased APM production of V. fetus due to the increased number of cells produced in its presence. Therefore, the addition of lactate to the 8 chemically defined mediums used for growth or APM production would be advantageous. Citrate and succinate, which increased the growth of V. fetus without affecting APM production, could be added to the chemically defined medium used for obtaining maximal growth of vibrios. Studies requiring a large cell crop of vibrios would be facilitated by the use of the chemically defined medium to which lactate, citrate, and/or succinate had been added. A large cell crop of V. fetus would be useful in preparation of V. fetus cellular antigen. Any study requiring large cell crops cf vibrios would be facilitated by the use of a medium which increased the growth of V. fetus. Alpha-ketoglutarate and tween 80 increased APM production of V. fetus, although these compounds neither increased nor decreased the growth of the vibrios. Therefore, the addition of α-ketoglutarate and tween 80 to the medium used for maximal production of APM would be advantageous. An increased production of APM by V. fetus would aid the study of the biosynthesis of APM. Also, the antigenic nature of APM could be studied more successfully by using a medium which increased the production of APM by vibrios. Compounds, such as glutathione and tergitol 7, which inhibited the growth and the production of APM of vibrios should not be added to the chemically defined medium. Glutamine and asparagine inhibited the growth of V. fetus and should also be avoided as additions to the medium.