1. 75 50 25 37 15 10 67851234 2.702.923.33.612.060.040.20.921.83OD 600 : Time (hr) : Media :LB + 0.4% NO 3 - 21% O 2 0 O 2 : ΔlasB mutant Elastase PAO1 Fig. S1. Aerobic growth of a ΔlasB mutant and SDS-PAGE analysis of its culture supernatants. The mutant bacteria grown overnight in LB at 37 °C were inoculated at 1:100 in LB + 0.4 % NO 3 -, and growth was monitored by measuring OD 600. Aliquots of the culture were harvested every hour and protein contents present in each culture supernatant (CS) were analyzed by SDS-PAGE. For a comparison, SDS- PAGE of the PAO1 CS harvested after 8 hr aerobic growth was shown to the right. The protein band that corresponds to the mature elastase is shown with an arrow.

2. Fig. S2. The effect of anaerobiosis on the elastase secretion of various P. aeruginosa strains including clinical isolates. (A) Strains indicated at the top were grown in LB plus 0.4 % (w/v) NO 3 - either aerobically (21% O 2 ) or anaerobically (0% O 2 ) for 18 hrs. The level of elastase was analyzed by SDS-PAGE. PA14 and PAK are non-mucoid pathogenic strains, while FRD1 is a mucoid laboratory strain derived from a CF patient. Pneu1, 2 and 3 are non-mucoid isolates from Korean pneumonia patients. (B) MTT cell viability assay of A549 human epithelial cells treated with cell-free culture supernatants (CS) of indicated strains. A549 cells were treated with the same set of CSs as in panel A. Experimental conditions are identical to those described for Fig. 1A. *p<0.01 vs. treatment with anaerobic CS. 25 37 PAO1PA14PAKFRD1 25 37 Pneu 1Pneu 2Pneu 3 21% O 2 0% O 2 21% O 2 0% O 2 A B Relative viability * * * * * *

3. Gene namePrimer sequences (5'-3') mvfR F : ATCAAGCAGGACAACGCGGA R : GCAGGGAGGCATTGCACAAC rsaL F : ACAGCCCCAAAACATGGCCT R : GGGCAGGTTCTCGCCATTCT vqsR F : AGCAGATCGCGCTGTTCGAG R : CTCCTCCCTGACCGCATCCT rhlR F : GCGCTTTCACATCGACCAGG R : GCGGTGGTGTATTCGTCCCA rhlA F : GCGCTTTCACATCGACCAGG R : GCGGTGGTGTATTCGTCCCA PA3904 F : GGTAGGTAGCGTCGGCACCC R : GGCATTGCAGGCACAGCTTC PA4677 F : CGAAGCGGTGTTCACCAAGC R : GCCGTAACGCTGCAACAACC xcpP F : GCGCGGACGACATTACAAGC R : CGAGTCTTCTTCGGCGGGTT pqsA F : CCACTCCGCTGGACGACAAC R : GCAGCATGTGCGAGGGAATC pqsC F : ATCTGTTCGGCTTCCTCGCC R : CGCACTCCATCTGCGAATCC lasB F : CCGCAAGACCGAGAATGACA R : CTTCCCACTGATCGAGCACT lasI F : TTCAAGGAGCGCAAAGGCTG R : GTTCTTCAGCATGTAGGGGC rhlI F : CTTCATCGAGAAGCTGGGCT R : AGGTAGGCGAAGACGTCCTT rpoD F : AAGGCCCTGAAGAAGCACGG R : GATCGGCATGAACAGCTCGG Table S1. Primers used for qRT-PCR