Studies on the morphology of colonies of bacilli of BCG-Poland substrain. I. The influence of iron on the type of BCG-Poland colonies.

The influence of iron concentration in Sauton's medium solidified with agar on the type of colonies of BCG-Poland substrains, BCG-Rio de Janeiro, BCG-France, BCG-Denmark and BCG-Japan substrains has been examined. Of all the studied BCG substrains only the BCG-Poland substrain formed rough (R) and smooth (S) colonies. In the investigated substrains rough colonies became smaller with the decrease of iron concentration but they retained their characteristic surface roughness. The smooth colonies which in the same conditions appeared only in BCG-Poland substrain did not display such dependency on iron concentration. When the incubation period was prolonged secondary rough colonies appeared among the smooth ones, regardless of the iron concentration in the medium.