Fig. 6.

The effect of reactive oxygen species on serum resistance is universal. A. Percent survival (gray line) and change in oxidation state of the roGFP2 probes (blue line) of E. coli incubated with fish serum (0–250 μL) in parallel samples. B. OxD kinetics of bacteria to H₂O₂(20 mM), glycine (100 mM), serum (100 μL) and serum (100 μL) plus glycine (100 mM) with biosensor, roGFP2-Orp1, expressed in E. coli were measured using the microplate reader. OxD was calculated using the 405/488 excitation ratio with emission at 510 nm. C. Percent survival of E. coli incubated with thiourea (150 mM), α-tocopherol (100 μM) or Fe³⁺(40 μM) in the presence or absence of 100 μL fish or mouse serum and glycine (100 mM). D. OxD of roGFP2-Orp1 expressed in E. coli were measured using the microplate reader after incubated with thiourea (150 mM), α-tocopherol (100 μM) or Fe³⁺(40 μM) in the presence or absence of 100 μL fish or mouse serum alone or in the presence of glycine (100 mM) for 2h. E. Percent survival of E. coli in the presence of H₂O₂ (1 mM), serum (100 μL) or both. F. OxD of roGFP2-Orp1 expressed in E. coli were measured using the microplate reader after incubated with H₂O₂ (1 mM), serum (100 μL), or both for 2h. G & H Quantification of C3b and C5b-9 on E. coli in the presence of H₂O₂(1 mM), serum (100 μL) or both. I & J Percent survival of E. coli incubated with thiourea (150 mM), α-tocopherol (100 μM), Fe³⁺(40 μM), H₂O₂ (1 mM) or glycine (100 mM) in the presence or absence of 100 μL serum for the indicated length of time. K. Percent survival of E. coli K12, ΔsoxS, ΔsoxR, ΔacrB, ΔacrA and ΔoxyR in the presence of 100 μL serum for 2h. Results are displayed as mean ± standard errors of the means (SEM) (N ≥ 3 technical replicates per sample), and statistically significant differences are identified. *, p < 0.05, **, p < 0.01. Each experiment was repeated independently at least three times. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)