Fig 4.

E. coli OP50 can resist the intrusion of Salmonella in the gut of older worms. (A) Gut densities of E. coli OP50 (black bars) and S. Typhimurium SL1344 (gray bars) recovered from C. elegans N2 after their growth on founder E. coli OP50 lawns and then after the substitution of S. Typhimurium lawns at several points in worm maturation (L4 stage plus 1, 2, 3, 4, or 5 days). Data represent means ± SD. (B) Intestinal bacteria recovered from C. elegans N2 after being switched from lawns of founder E. coli OP50 (black bars) to lawns of S. Typhimurium SL1344 (gray bars), which were transferred on day 3 (L4 plus 3), with worms then maintained on the introduced S. Typhimurium strain with sampling of the worms at 24, 48, and 96 h after the shift.