Fig. 1.
T6S antagonism in the gut is species-dependent. (A and B) B. thetaiotaomicron (Bt) is susceptible to B. fragilisN (Bf) T6S in vitro (A) but not in vivo (B). (C and D) B. vulgatus (Bv) is susceptible to B. fragilisN T6S both in vitro (C) and in vivo (D). For in vitro competitions (A and C), competitive index calculations are normalized to tssC controls and *P < 0.05. Error bars indicate ± SD (n = 2; representative of four independent trials). For gnotobiotic mouse studies (B and D), B. thetaiotaomicron or B. vulgatus was introduced into germ-free mice with WT (red bars) or tssC (black bars) B. fragilisN, and the abundance of each strain was determined by quantitative PCR using gDNA from fecal samples collected over time. *P < 0.05 between recipient populations in each group (n = 5 mice per group; representative of two independent trials); error bars indicate ± SD.