Values of 0.60 +/- 0.04 g.g^-1 and 0.056 +/- 0.014 g. (g.h)^-1 for the true growth yield and maintenance coefficient respectively, where obtained in a glucose-(NH₄)₂SO₄ based synthetic medium (MFA). No toxicity against Aedes aegypti was found in final samples taken from cultures performed in MFA medium when the inoculum was prepared in MFA medium. On the other hand, when the inoculum was grown in MFA medium supplemented with yeast extract the toxicity attained in MFA medium increased with the inoculum size up to a inoculum rate of 1.4 %, and then it remained nearly constant (around 3000 ITU / mg) at higher inoculum rates (up to 15%).