Fig. 5

Role of harsh conditions in influencing darobactin production and antimicrobial activity. A Darobactin concentration (μg/mL) in M9 Minimal Media sustaining the pre-cultivated biomass of pTAMP-DarA-AT EcN strain (no antibiotic supplementation) after 2 h incubation at 37 °C and 40 °C (thermal induction), followed by an additional 4 h incubation at 37 °C. The error bars represent standard deviation based on three independent measurements (***p = 0.0004 as calculated by paired t-test) (B) End-point absorbance (OD₆₀₀) of P. aeruginosa PAO1 after 18 h incubation at 37 °C in filter-sterilized M9 Minimal Media containing the pTAMP-DarA-AT EcN strain. The samples subjected to thermal induction (40 °C) for 2 h followed by an additional incubation at 37 °C for 4 h demonstrate significant growth inhibition of P. aeruginosa PAO1. The error bars represent standard deviation based on three independent measurements (*p = 0.0234 as calculated by paired t-test) (C) Darobactin concentration (μg/mL) in M9 Minimal Media supplemented with 0.3% (w/v) Bovine Bile sustaining the pre-cultivated biomass of pTAMP-DarA-AT EcN strain (no antibiotic supplementation) after 2 h incubation at 37 °C and 40 °C (thermal induction), followed by an additional 4 h incubation at 37 °C. The error bars represent standard deviation based on three independent measurements (***p = 0.0005 as calculated by paired t-test) (D) End-point absorbance (OD₆₀₀) of P. aeruginosa PAO1 after 18 h incubation at 37 °C in filter-sterilized M9 Minimal Media supplemented with 0.3% (w/v) Bovine Bile, containing the pTAMP-DarA-AT EcN strain. The samples subjected to thermal induction (40 °C) for 2 h followed by an additional incubation at 37 °C for 4 h demonstrate significant growth inhibition of P. aeruginosa PAO1. The error bars represent standard deviation based on three independent measurements (*p = 0.0328 as calculated by paired t-test)