Infective and noninfective strains of Borrelia burgdorferi, along with Borrelia afzelii and Borrelia garinii, possessed a single iron-containing superoxide dismutase (SOD). None of the Lyme disease spirochetes tested possessed catalase or peroxidase activities. The borrelial SOD was not inducible by growth with increased oxygen concentrations and thus appeared to be produced constitutively.

Representative members of Spirochaetales were surveyed for their content of superoxide dismutase (SOD), catalase, and peroxidase activities. Only Leptospira exhibited peroxidase activity. Obligately anaerobic cultivable Treponema and Spirochaeta possessed no SOD or peroxidative capabilities. Upon polyacrylamide gel electrophoresis, Spirochaeta aurantia, Borrelia hermsi, and five Leptospira biflexa serovars showed SOD activity associated with one electrophoretic band which was inhibited by H202, suggesting that they were iron-containing dismutases. These spirochetes could be distinguished by differences in relative mobilities of their SODs. SOD activity, but not catalase activity, was induced aerobically in S. aurantia. All Leptospira interrogans serovars and two L. biflexa serovars lacked significant SOD activity. These SOD-deficient strains of Leptospira, with one exception, possessed high levels of catalase activity. The Nichols strain of virulent Treponema pallidum possessed SOD and catalase activities, but lacked peroxidase activity. The SOD in T. pallidum exhibited two electrophoretic bands containing copper and zinc, and its relative mobility was identical to that of purified rabbit SOD. Immunization of sheep with purified rabbit SOD resulted in antiserum which inhibited both rabbit SOD and T. pallidum SOD assayed by spectrophotometric analysis or activity staining following polyacrylamide gel electrophoresis. In agarose gel diffusion, precipitin lines of identity were observed between purified rabbit SOD and cell extracts of T. pallidum. These data indicated that the SOD activity detected in T. pallidum was host derived.

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Zones of beta-hemolysis occurred around colonies of Borrelia burgdorferi grown on Barbour-Stoenner-Kelly medium containing agarose and horse blood. Blood plates were inoculated with either the infective strain Sh-2-82 or noninfective strain B-31 in an overlay and incubated in a candle jar. Both strains of B. burgdorferi displayed beta-hemolysis after 1 to 2 weeks of incubation. The hemolytic activity diffused out from the borrelial colonies, eventually resulting in lysis of the entire blood plate. Hemolysis was most pronounced with horse blood and was less intense with bovine, sheep, and rabbit blood. Hemolysis was enhanced by hot-cold

The infectivity of Borrelia burgdorferi depends on the number of passages in Barbour-Stoenner-Kelly (BSK-II) medium in ambient air. In this study the parameters of medium formulation or O2-CO2 atmosphere were altered to define conditions that would retain borrelial infectivity upon serial passage. The infective strain Sh-2-82 was passaged 20 times in BSK-II and BSK-A (a modified BSK-II medium) in ambient O2-CO2 and BSK-II in 4% O2 - 5% CO2 - 91% N2. Spirochetes of every fifth passage were inoculated intraperitoneally into neonatal Lewis rats. Infectivity was lost after 15 passages in media in ambient O2-CO2. However, infectivity was maintained through all 20 passages in BSK-II in 4% O2 - 5% CO2 - 91% N2. There were no pH differences, but the dissolved O2 concentration in ambient O2-CO2 was approximately twice that in 4% O2 - 5% CO2 - 91% N2. Therefore, differences in infectivity were due to culturing under a constant environment of decreased O2 and increased CO2. This environment may place a selective pressure on the borreliae for retention of the infective phenotype. The results suggest that the levels of O2 and CO2 in the environment influence infectivity by preventing the loss of genetic information or inducing the expression of virulence determinants in B. burgdorferi.