Draft Genome Sequence of the Axenic Strain Phormidesmispriestleyi ULC007, a Cyanobacterium Isolated from Lake Bruehwiler (Larsemann Hills, Antarctica)

ABSTRACT Phormidesmis priestleyi ULC007 is an Antarctic freshwater cyanobacterium. Its draft genome is 5,684,389 bp long. It contains a total of 5,604 protein-encoding genes, of which 22.2% have no clear homologues in known genomes. To date, this draft genome is the first one ever determined for an axenic cyanobacterium from Antarctica.

The growth of an axenic strain ofEntamoeba invadensin different media

The growth of an axenic strain ofEntamoeba invadensin two media (Trypticase–liver broth and Trypticase–Panmede) is compared with that of a monobacterial strain in diphasic medium supplemented with starch. The axenic strain multiplied more slowly, and produced lower yields of amoebae than the monobacterial strain.Amoebae multiplied more rapidly and produced higher yields in Trypticase–liver broth than in Trypticase–Panmede.The effect of certain variations in the basic Trypticase–Panmede medium was investigated. Serum stimulated the growth of the axenic strain in Trypticase–Panmede, so that although the initial multiplication rate was not increased, the maximum yields of amoebae were increased to levels that varied according to the concentration of the serum.The multiplication of the axenic amoebae was depressed by procedures which probably aerated the medium.I thank Dr L. S. Diamond for axenic strain NIH:200 ofE. histolytica, and Professor E. Meerovitch for axenic strain PZ ofE. invadens. I am much indebted to Dr P. Whittlestone, of the Department of Animal Pathology, Cambridge, who examined cultures of strain N for the presence of mycoplasmata. The work was carried out while the author was a member of the scientific staff, Medical Research Council.

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

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.