Figure 5. Pyruvate Protects Pathogenic Strains of Leptospira interrogans Against H₂O₂.

(A) L. interrogans serovar Manilae L495 was challenged with GOX (0.32 mU ml⁻¹) in EMJH medium with and without added pyruvate (PYR). Stationary phase cultures were diluted to 10⁶ cells ml⁻¹ in EMJH medium with glucose (2 g L⁻¹) and with or without PYR (910 µM). After 1.5 days of growth, GOX was added, indicated by the arrowhead and growth was monitored by direct counting of spirochetes by dark field microscopy. The limit of detection (LOD) for direct counting is indicated by a solid line and cultures with spirochetes below the LOD are indicated by the arrow pointing to the line, which corresponds to ≈10⁴ spirochetes ml⁻¹. (B) L. interrogans serovar Lai 56601 was challenged with GOX as described above. Results in (A) and (B) show the mean ±1 SD from three separate experiments performed in duplicate or triplicate.