Fig 5.

Complementation activity of L. monocytogenes and B. subtilis DivIVA chimeras in the B. subtilis ΔdivIVA background. (A) Phase-contrast micrographs showing the ability of the tested L. monocytogenes and B. subtilis DivIVA chimeras to complement the filamentous ΔdivIVA phenotype. Cells were cultivated in LB broth containing 0.5% xylose until mid-log growth phase at 37°C before cell morphology was assessed microscopically. Bar, 5 μm. (B) Sporulation plate assay to test the activity of the L. monocytogenes and B. subtilis DivIVA chimeras to complement the sporulation defect of the B. subtilis ΔdivIVA mutant. Strains expressing the DivIVA chimeras were streaked on Schaeffer′s sporulation agar containing 0.5% xylose and kept at 37°C until lysis of nonsporulating strains was comfortably distinguishable from the brownish Spo⁺ strains. The wild type, the ΔdivIVA mutant, and strains complemented with either the B. subtilis (BSN51) or the L. monocytogenes (BSN238) divIVA gene were used as controls. Sections: 1, strain 168 (wt); 2, strain 4041 (ΔdivIVA); 3, strain BSN51 (B. subtilis divIVA); 4, strain BSN238 (L. monocytogenes divIVA); 5, strain BSN274 (Lm-144-Bs divIVA); 6, strain BSN278 (Lm-130-Bs divIVA); 7, strain BSN288 (Lm-104-Bs divIVA); 8, strain BSN287 (Lm-83-Bs divIVA); 9, strain BSN316 (Lm-71-Bs divIVA); 10, strain BSN321 (Bs-57-Lm divIVA). Note that sporulation of strain BSN288 (Lm-104-Bs divIVA) did not reach the wild-type level. This might be explained by the lack of MinCD activity in this strain, which is required for full sporulation (37).