Lactic acid has no action on M. tuberculosis after six days of contact, in concentrations of 0.1 and 0.5%.
At 1% lactic acid has some noxious effect on the germ after four days of contact; this action is increased, without becoming absolute, in six days of contact.
Lactic acid of 2% has a manifest noxious effect on M. tuberculosis in four days of contact; in six days, this action is nearly absolute.
Lactic acid at 5 and 10% kills the bacillus in two days of exposure.
The lactic acidity of "Chanco" cheese reaches an average of 1.8 per cen around the eighth day of ripeding.
Lactic acid at 1.8% maintained in contact with M. tuberculosis during eight days has an absolute bactericidal effect.
Lactic acidity higher than 1.8 gm. per cent reached in "Chanco" cheese during the process of ripening and which persists more than eight days, kills M. tuberculosis.