Two strains of Sulfolobus acidocaldarius, a thermoacidophilic archaeba
cterium, were examined for their pyrite-oxidizing ability. S. acidocal
darius ATCC 33909 was shown to possess iron-oxidizing activity by ferr
ous sulfate oxidizing experiments, but S. acidocaldarius No. 7 did not
have it. Pyrite-oxidizing rate of S. acidocaldarius ATCC 33909 was 1.
6-fold higher than that of strain 7 though they had a similar level of
sulfur-oxidizing ability. These results show that the iron-oxidizing
activity accelerates pyrite oxidation.