Nutrition of Leptospira pomona. 1. A chemically defined substitute for rabbit serum ultrafiltrate.

Johnson, R. C. (Fort Detrick, Frederick, Md.) and N. D. Gary. Nutrition of Leptospira pomona. I. A chemically defined substitute for rabbit serum ultrafiltrate. J. Bacteriol. 83:668-672. 1962.-Poor growth of Leptospira pomona, strain Wickard, in a medium containing exhaustively dialyzed rabbit serum was corrected by addition of rabbit serum ultrafiltrate. A dialyzed serum medium was used to investigate the nutritional qualities of various compounds when tested as substitutes for the ultrafiltrate fraction. l-Asparagine was the only amino acid that markedly stimulated growth. l-Glutamine was active only when autoclaved (converted to the ammonium salt of pyrrolidone carboxylic acid), and NH(4)Cl and urea satisfactorily replaced l-asparagine. Results indicated that amino acids functioned primarily as a nitrogen source in this medium. Thiamine was the only vitamin required for growth. The lag phase was usually decreased by 1 day with NaHCO(3).A medium composed of 0.02 m phospate buffer (pH 7.4), 15% dialyzed rabbit serum, thiamine (5 mug/ml), and NH(4)Cl (10(-3)m) supported growth equivalent to that obtained with undialyzed rabbit serum medium. L. pomona was transferred six times, in this medium and seven other serotypes were transferred three times, without any decrease in amount of growth. Growth of L. pomona was initiated with 20 organisms per ml.