Amino acid, heme, and sterol requirements of the nematode, Rhabditis maupasi.

Rhabditis maupasi, a nematode that occurs in the mantle cavity of Helix aspersa and related North African food snails, requires 5 amino acids (lysine, methionine, phenylalanine, tryptophane and valine) for maintenance of the stage-3 survival larvae, and 5 additional amino acids (arginine, isoleucine, leucine, threonine and, marginally, histidine) for development of these larvae into adults and for reproduction. Tyrosine is beneficial but not absolutely required for reproduction. These results were obtained with axenic R. maupasi grown in a chemically defined medium containing salts, trace metals, purines and pyrimidines, Krebs cycle intermediates, a fatty acid (butyric), vitamins, urea, and a carbohydrate (dextrose). The complete medium contained 18 amino acids; each of 18 test media was deficient in one of the amino acids. In the complete medium and in a medium lacking the "nematode nonessential" amino acids, stage-3 R. maupasi developed into adults and produced one generation of offspring. For continuous cultivation, however, the nematode also required hemin or another iron porphyrin as well as a sterol such as cholesterol.