Metabolically active bacteria are required for the differences in lifespan between wild-type and ahr-1 on HT115. (A) ahr-1 mRNA expression in wild-type worms feeding on HT115 or OP50. Pooled data of 3 independent replicates are shown. No statistical significance was observed with the t-test. (B–D) Survival upon heat stress in 7-days old wild-type and ahr-1(ju145) feeding on either HT115 or OP50. Pooled data of 60 worms/condition in 3 independent experiments are shown. * p-value < 0.05 vs. wt, # p-value < 0.05 vs. HT115, statistical test: Log-rank test. (B) Alive bacteria were used as a food source. (C) Bacteria were killed by UVB irradiation before seeding to the NGM. (D) Bacteria had grown on the NGM for 2 days before being killed by UVB irradiation. (E) Kaplan Meier curves of wild-type and ahr-1(ju145) on UVB-killed bacteria. Pooled data of 120 (wt HT115, ahr-1 HT115, ahr-1 OP50) and 110 (wt OP50) worms in 2 independent experiments are shown. * p-value < 0.05 vs. wt, # p-value < 0.05 vs. HT115, statistical test: Log-rank test.