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Figure 1 | BMC Microbiology

Figure 1

From: In Helicobacter pylori auto-inducer-2, but not LuxS/MccAB catalysed reverse transsulphuration, regulates motility through modulation of flagellar gene transcription

Figure 1

The Δ luxS Hp mutant of H. pylori strain J99 lacks AI-2 and is non-motile unlike other mutants deficient in cysteine biosynthesis. (A) AI-2 production in J99 wild-type (black column), ΔluxSHp (red column), ΔmccBHp (blue column) and ΔmccAHp (white column) mutants was measured. Strains were grown in Brucella broth, and aliquots were removed at 24 h, 30 h, 48 h and 72 h to assess the optical density (wild-type, square; ΔluxSHp, diamond; ΔmccBHp, circle; ΔmccAHp, triangle) and the amount of AI-2 in the filtered culture supernatant using the V. harveyi bioassay. AI-2 activity is shown as a relative bioluminescence (corrected by OD600nm of H. pylori) in the presence of H. pylori culture supernatants over the negative control (Brucella broth alone). A diluted in vitro synthesised AI-2 sample was utilised as a qualitative positive control [8]. Bioluminescence induced by wild-type, ΔmccBHp, and ΔmccAHp strains was significantly greater than that induced by the ΔluxSHp mutant, as determined by paired Student's t-test (p < 0.001). The lines represent the growth (OD, righthand axis) and the bars represent the AI-2 activity (bioluminescence, lefthand axis). (B) 5 μl of liquid culture (24 h) of the wild-type, ΔluxSHp, ΔmccBHp and ΔmccAHp mutants was seeded on each quarter of a soft agar plate. After 3, 5 and 7 days of incubation, the motility halo of each strain was recorded using a digital camera. All experiments were done in triplicate: a representative experiment is shown and the mean results are presented in the text.

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