FIG 2.

Cell density influences the extent of growth inhibition of EGD-e by blue light. Dilutions of EGD-e were illuminated with blue light (460 to 470 nm, 1.5 to 2.0 mW cm⁻²) either on BHI agar (A) or in BHI liquid culture (B). (A) Overnight cultures were standardized to an OD₆₀₀ of 1.0 and diluted to 10⁻⁸. Four microliters of each dilution was spotted in triplicate onto BHI agar and grown at 30°C for 24 h. (B) White bars represent growth in the presence of light, and the black bars represent the dark control. The graphs show final OD₆₀₀ measurements (left) and lag times (right). The number over the lag time indicates the time taken to reach an OD₆₀₀ of 0.1. Starting cells were equalized to an OD₆₀₀ of 0.05 and diluted to 10⁻⁶. Cultures were grown in 96-well plates at 30°C for 24 h. The values represent the means of the results from three individual replicates. The error bars represent the standard deviations between replicates. Student's t test was carried out to determine the statistical difference (P ≤ 0.05, indicated with an asterisk) between cultures grown in light and dark.