Modification and elimination of the bacterial flora in cultures ofEntamoeba invadensRodhain, 1934

Abstract

1. Cysts, formed in a strain ofE. invadensgrowing with a mixed bacterial flora, were sterilized of all but one species of bacterium (organismx), by treatment with chemicals. Strains ofE. invadensderived from these cysts were prepared, growing with organismxand eitherBact. coliorB. megatherium.2. A monobacterial strain ofE. invadens, growing withBact. colialone, was obtained by maintaining a dibacterial strain, growing with organismxandBact. coli, for 72 days in medium containing gentian violet.3. A monobacterial strain ofE. invadens, growing withStaph. albus, was prepared from cysts, produced in the monobacterial strain ofE. invadens + Bact. coli, and sterilized by treatment with chemicals.4. An axenic strain ofE. invadenswas prepared by maintaining the monobacterial strain ofE. invadens + Staph. albus, in saline-liver medium containing antibiotics. This axenic strain has now been maintained for over 14 months in saline containing untreated, sterile liver, but no antibiotics.