The response of gram-negative, thermophilic bacteria to oxygen.

Nine gram-negative, thermophilic bacteria (LEH-1, CC-6, BI-1, NR-9, K-2,Thermus aquaticus, T. thermophilus, T. sp. X-1, andThermomicrobium roseum) tolerated increased oxygen tensions (0.6-1.0 atm). All of the strains demonstrated catalase, peroxidase, and superoxide dismutase activity. Except forT. roseum, the specific activity of one or more of these enzymes was higher under aerated culture, as compared to static conditions. Polyacrylamide gel electrophoresis (PAGE) indicated that each organism possessed only one superoxide dismutase, and each was tentatively identified as having a manganese prosthetic group. PAGE also demonstrated that the number of isozymes of catalase varied from one to three, depending on the organism. Finally, the characterization of these enzymes supported previous tentative groupings of these thermophiles.