Fig. 8

Effects of the yifE mutant and putrescine transporter PotFGHI on putrescine production. a The putrescine concentration in the supernatant of the culture media of strains KT152, KT160, and KT161 grown in terrific broth supplemented with 100 μg/mL of ampicillin for 48 h. When the OD₆₀₀ reached 0.4, 0.02 mM IPTG was added. b The putrescine concentration in the supernatant of the culture media of strains KT160 grown in terrific broth supplemented with 100 μg/mL of ampicillin. When the OD₆₀₀ reached 0.4, 0.01 mM IPTG was added. * p < 0.001; ns, not significantly different. yifE: WT, yifE^wt; Q100TAG, yifE^Q100TAG gene. potFGHI: + , presence of potFGHI operon; -, absence of potFGHI operon. [IPTG]: 0.01 and 0.02 is the optimum concentration of IPTG in terms of mM. Data shown are averages ± standard deviations, and culture experiments were performed in triplicate