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. 2022 Jan 25;13(1):e03752-21. doi: 10.1128/mbio.03752-21

FIG 4.

FIG 4

Glucose and indole reciprocally regulate cytotoxin synthesis by K. oxytoca strain AHC-6 and the AHC-6ΔtnaA mutant. (A) Comparison of UCH-1 growth with AHC-6 and AHC-6ΔtnaA in LB medium with glucose (LBG) at 37°C for 6 h (n = 3 to 7). (B) Analysis of tilimycin and tilivalline metabolite levels from 18-h culture supernatants of AHC-6 and AHC-6 ΔtnaA grown in LB medium with or without added glucose determined by LC-MS. ND, not detected (n = 3 to 8). (C) Effect of indole (1 mM) on npsA and npsB expression in AHC-6 and AHC-6 ΔtnaA grown in LBG. Transcript copy numbers for npsA and npsB (per 100 copies of recA transcript) in samples obtained at postexponential (6 h) growth phase (n = 6 or 7) were determined by RT-qPCR. (D) Effect of indole (1 mM) on tilimycin and tilivalline metabolite levels from 18-h culture supernatants of AHC-6 and AHC-6 ΔtnaA grown in LBG determined by LC-MS (n = 3 to 7). The data represent mean values ± standard errors of the means. Statistical analysis was done by Mann-Whitney U test. In samples where no tilivalline was detected, the detection limit by LC-MS was used for statistics. Where stated, “vehicle” means addition of DMF (0.1%). *, P ≤ 0.05; **, P ≤ 0.01.