Survival of <i>B</i>. <i>subtilis</i> Δ<i>hfq</i>_<i>Bs</i> in competition with <i>hfq</i>-expressing strain.

<p>A) Co-cultures were performed with <i>hfq</i>_<i>Bs</i>-expressing strain and Δ<i>hfq</i>_<i>Bs</i> mutant in LB medium and incubated at 37°C during 5 days. An antibiotic resistance gene (<i>cat</i> or <i>spc</i>) was inserted in the intergenic region <i>hfq-ymzE</i> (control, black) or in replacement of the <i>hfq</i>_<i>Bs</i> coding sequence (mutant, white). Each population was numbered on LB plates supplemented with spectinomycin or chloramphenicol. To number spores, samples were incubated 15 min at 80°C before plating (dot lines). Two combinations of co-cultures were performed using two sets of isogenic strains (●) TR247 (<i>hfq</i>_<i>Bs</i>⁺<i>igr</i>::<i>cat</i>) and (◊) TR232 (Δ<i>hfq</i>_<i>Bs</i>::<i>spc igr</i>+) or strains (○) TR223 (Δ<i>hfq</i>_<i>Bs</i>::<i>cat igr</i>+) and (♦) TR241 (<i>hfq</i>_<i>Bs</i>⁺<i>igr</i>::<i>spc</i>). B) The same experiments were performed with sporulation-deficient derivative strains (<i>sigE</i>::<i>erm</i>). The two co-cultures were performed using strains (●) TR243 and (◊) TR237 or strains (○) TR235 and (♦) TR245. C) Competition experiments were performed with TR259 and TR255 strains which are deleted of the <i>bsrE</i>-asBsrE type 1 TA and express (●) or not (◊) Hfq_<i>Bs</i>. D) Competition experiments were performed with the TF8A (<i>txpA</i>-RatA deleted) derivative strains using Δ<i>hfq</i>_<i>Bs</i> TR248 (◊) and control TR252 (●) strains.