2.2. Culture of OP50 Strain and Maintenance of C. elegans

OP50 bacteria was grown in lysogeny broth medium (LB: tryptone 10 g/L, yeast extract 5 g/L and NaCl 10 g/L) at 37 °C with stirring. Worms were maintained at 20 °C on nematode growth medium (NGM: agar 20 g/L, peptone 2 g/L, NaCl 41 mM, KH₂PO₄ 20 mM pH 6.0, MgSO₄ 1 mM, CaCl₂ 1 mM and cholesterol 5 mg/L) agar plates seeded with OP50 bacteria. Before each experiment, eggs were harvested from gravid worms by lysis with sodium hypochlorite. Young adult worms were then obtained from synchronized L1 larvae after culture of eggs for 20 h in M9 buffer (NaCl 86 mM, Na₂HPO₄ 42 mM, KH₂PO₄ 22 mM and MgSO₄ 1 mM).

Except for maintenance and larval development, feeding bacteria were 10 times concentrated and heat-inactivated 30 min at 65 °C.