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. Author manuscript; available in PMC: 2014 Jun 5.
Published in final edited form as: Science. 2011 Nov 18;334(6058):982–986. doi: 10.1126/science.1211037

Figure 2. HAQs mediate antibiotic susceptibility in the ΔrelA spoT mutant.

Figure 2

A. Endogenous levels of hydroxyl radicals (OH•) in biofilms. OH• was measured using the probe HPF (3’-p-hydroxyphenyl fluorescein). Error bars indicate SD. P ≤0.005 (*) versus wild type.

B. Autolysis occurs in the ΔrelA spoT mutant after prolonged growth on agar (arrow). Scale bar indicates 2.5 mm.

C. Spontaneous cell death in ΔrelA spoT biofilms detected by viability staining (live cells are green, dead cells red). Images were acquired with the same microscope settings.

D. HAQ measurements by LC/MS. Error bars indicate SD. P ≤0.01 (*) versus wild type.

E. Antibiotic killing of biofilms treated with ofloxacin (30 µg/mL), meropenem (300 µg/mL), colistin (300 µg/mL) and gentamicin (50 µg/mL). Error bars indicate SD. P ≤0.0005 (*) or ≤0.05 (**) versus wild type.

F. Relationship between HAQ levels, ofloxacin tolerance, and [OH•] in wild type and ΔrelA spoT biofilms. Strains producing graded HAQ expression in the wild type include: a) ΔpqsA ctrl, b) wild type ctrl, c) ΔpqsA pqsA-E+. Strains producing graded HAQ expression in ΔrelA spoT include: d) ΔrelA spoT pqsA ctrl, e) ΔrelA spoT pqsA pqsA-C+, f) ΔrelA spoT ctrl, g) ΔrelA spoT pqsA pqsA-E+. Error bars indicate SD. Biofilm killing P ≤0.001 (*) versus ΔpqsA ctrl; OH• levels P ≤0.05 (**) versus ΔpqsA ctrl.