sequencing of the ''military'' isolates revealed a frameshift mutation in the katA gene encoding the major vegetative catalase [41] . The absence of catalase activity in ''military'' isolates was confirmed by adding a solution of 3% H 2 O 2 to smears of various strains. In contrast to the 1942 strain, which exhibited immediate and robust catalase activity, the strains containing the frameshift lacked this activity. A small amount of bubbling could be seen, probably due to the presence of a second catalase normally packaged in spores [42] .