Table 1.
Strains and plasmids used in this study.
Table 2.
Comparison of NCDO712 plasmids with earlier studies.
Fig 1.
Plasmid maps of pSH73, pSH74, and pNZ712.
Plasmid pNZ712 includes genes encoding functional nisin immunity (nisCIP) and copper resistance (lcoRSABC). The 16-kb plasmid pSH74 contains a novel 8-kb pilus gene cluster spaCB-spaA-srtC1-srtC2. Plasmid pSH73 harbors repX, repB and cadCA genes. The latter genes were annotated as a cadmium resistance regulatory protein and a cadmium efflux ATPase.
Fig 2.
Schematic representation of the pilus gene cluster on pSH74 and the suggested functions of its constituting genes (not to scale).
The internal deletion of 1451 bases in spaCB is indicated in red.
Fig 3.
Cell aggregation after pilus gene over-expression.
A—L. lactis NCDO712, B—empty vector control MG1363(pIL253), C—MG1363(pIL253pilΔ1), D—MG1363(pIL253pil). The images were taken 3 min after re-suspension of cells from an overnight culture.
Fig 4.
Pilin gene overexpression in L. lactis MG1363 leads to increased chain length.
A—MG1363(pIL253), B—MG1363(pIL253pil), C—MG1363(pIL253pilΔ1).
Fig 5.
Scanning electron microscopy at 50.000 x magnification of L. lactis strains over-expressing spaCB-spaA-srtC1-srtC2.
A—NCDO712, B—IL1403, C—IL1403(pIL253pil), D—MG1363(pIL253), E—MG1363(pIL253pil), F—MG1363(pIL253pilΔ1). White arrows indicate pili in panel C. Black bars: 2 μm in all panels.
Fig 6.
Scanning electron microscopy of spaCB-spaA-srtC1-srtC2 over-expressing L. lactis strains.
A—NCDO712(pIL253pil), B—NCDO712, C—MG1363(pIL253pil), D—MG1363(pIL253), E—IL1403(pIL253pil), F- MG1363(pIL253pilΔ1). Black bars: 1 μm in all panels.