Figure 2.
In vitro characteristics of ara operon-deleted S. typhimurium. (A) Bacterial growth curves. Growth was assessed for ΔppGpp S. typhimurium (SL) and ara operon-deleted ΔppGpp S. typhimurium (SLΔARA). SL and SLΔARA was transformed with pClyA (SL-pClyA and SLΔARA-pClyA). SL-pClyA (-) or SLΔARA-pClyA (-) indicates without induction, while SL-pClyA (+) or SLΔARA-pClyA (+) indicates with induction by 0.002% or 0.2% L-arabinose. L-arabinose was added to the growth medium at 1.5 h. (B) SL and SLΔARA were transformed with pRLuc8. Various concentrations (0–0.4%) of L-arabinose were added to fresh bacterial cultures (after 1.5 h of culture) when the OD600 was 0.5–0.7. After 4.5 h incubation, ∼8 × 107 bacteria were collected for the luciferase assay (n = 5 per group). Bioluminescence, indicative of RLuc8 expression, was detected using a luminometer.