FIG 8.

Spermidine biosynthesis pattern and regulatory spectrum. (A) Spermidine levels of wild-type strain PAO1 in different media at different time points. (B) RNA levels of speE in wild-type strain PAO1 and mutant ΔspuE with or without different concentrations of spermidine. (C) Transcriptome analysis revealed the T3SS genes affected by null mutation of the spermidine synthase gene speE. (D) RT-qPCR analysis of the T3SS-related genes affected by null mutation of speE. Total RNAs were collected when bacterial strains were grown to an OD₆₀₀ of 1.0 to 1.3 with or without exogenous supplement of spermidine in MMN medium. The rpoD gene was used as an internal control. Experiment was repeated at least triplicates in each assay and error bars indicate standard deviations. Statistics significance: *, P < 0.05; **, P < 0.01; ***, P < 0.001. Statistical comparison was performed by using Student's t test. Statistical analysis compared of wild-type strain PAO1 and mutant ΔspeE in MMN was performed by using Student’s t test.