Fig 8. SpTrf proteins and rSpTrf-E1 show partial activity to retard bacterial growth.

Vibrio diazotrophicus, Bacillus cereus, B. subtilis, or Escherichia coli were grown to OD₆₀₀ = 1, and 10 μl were incubated with increasing concentrations of cNi-SpTrf proteins isolated from sea urchins A, B, and C, or with increasing concentrations of rSpTrf-E1. Bacterial growth was determined in triplicate by measuring the turbidity by OD₆₀₀ at 0, 2, and 4 hr. Data are presented as growth or OD₆₀₀ relative to time in the presence of increasing amounts of SpTrf proteins (μg/200 μl). The mean background OD₆₀₀ for the blank wells without bacteria was subtracted from the corresponding experimental time points. Student’s one-tailed t test was used to evaluate the significance of change in turbidity in the absence of SpTrf proteins compared to the range of SpTrf protein concentrations added to the cultures. Statistical significance is indicated by **, p ≤ 0.005; *, p ≤ 0.05. ns, not significant.