Figure 3: Surfactin restores the growth yield of strain 168 due to increased oxygen diffusion.

(A) Strain 3610 aerobic cultures achieve a significantly higher growth yield than strain 168. *: time period over which strain 168 growth differed significantly from that of strain 3610 (p<0.05, Student’s t-test). Lines represent the mean and shading represents 1 SD, n=3.

(B) Surfactin addition rescues growth yield. Growth curves of strain 168 with surfactin restored genetically (168sfp+) or 48 μM added exogenously at inoculation (168+srf_0h) or at t=3 h (168+srf_3h). Lines represent the mean and shading represents 1 SD, n=3. The mean growth curve from strain 3610 (A) is shown as a dotted blue line. Inset: rescaled to highlight growth divergence.

(C) Tween 80 addition rescues growth yield in a concentration-dependent manner. Lines represent the mean and shading represents 1 SD, n=3. The mean growth curve from strain 3610 (A) is shown as a dotted blue line. Inset: rescaled to the period of growth divergence.

(D) Surfactin addition increases oxygen levels during late exponential phase. Relative oxygen levels (bottom) during growth (top) of strain 168 with added surfactin (48 μM) or Tween 80 (0.76 mM). *: time period over which oxygen levels of 168+surfactin (yellow) or 168+Tween 80 (black) were significantly different from untreated 168 cultures (p<0.05, Student’s t-test).

See also Figure S4.