subtilis

strains MO1099 (Guérout-Fleury et al., 1996), IB1056 (Barák et al., 2008) and 1920 (Edwards & Errington, 1997) with selection for spectinomycin to yield strains IB1106, IB1107 and IB1108. Escherichia coli cells were grown in Luria–Bertani (LB) medium (Ausubel et al., 1987) at 37 °C or 28 °C. Bacillus subtilis cells were grown in LB or in Difco sporulation medium (DSM; Schaefer et al., 1965) at 37 °C. DNA manipulations and E. coli transformations were XL765 datasheet performed using standard methods (Sambrook et al., 1989). Methods for transformation of B. subtilis and other usual genetic techniques were used as described previously (Harwood & Cutting, 1990). Media were supplemented, when required, with ampicillin (100 μg mL−1), spectinomycin (100 μg mL−1), erythromycin (1 μg mL−1) together with lincomycin (25 μg mL−1), kanamycin (10 μg mL−1), chloramphenicol (5 μg mL−1) or tetracycline (5 μg mL−1). Xylose concentrations of 0.05–0.3% were used for the induction of the Pxyl; Phyperspank driven expression was induced using 0.1–1.0 mM isopropyl β-d-1-thiogalactopyranoside (IPTG). The expression levels of GFP and YFP fusion proteins were determined by Western blot analysis with an anti-GFP antibody (Roche Diagnostics) as described

previously (Barák et al., 2008). The cell cultures, for these purposes, were grown in DSM medium supplemented with an appropriate induction level of xylose or IPTG to mid-exponential phase. Bacillus subtilis cultures were inoculated from a fresh overnight plate to an OD600 nm of 0.1 and grown to mid-exponential phase (OD600 nm of 0.3–0.5) as liquid cultures in DSM. When it was necessary selleck kinase inhibitor to increase cell density, cells were concentrated by centrifugation (3 min at 9200 g) and resuspended in a small volume of supernatant before examination by microscopy. Cells were examined microscopically on freshly prepared poly l-lysine-treated slides or slides with a thin layer of 1% agarose in LB. The cell length was measured as the axis length from one cell pole to the other CHIR99021 and evaluated using Olympus image-pro

plus 6.0. The cells that had already divided but were not separated yet were counted and measured as two individual cells. Cells were counted as two separated cells only when the constriction was completed. The average cell length was determined from at least two independent measurements, each time from more than 200 cells (more than 500 cells together). Minicells were not included in the calculations of the average cell lengths and in the graphs of cell length distribution, and their occurrence was calculated separately. To visualize the cells and septa membranes, the cell cultures were stained using FM 4-64 dye (Molecular Probes) at a concentration of 1 μg mL−1. All images were obtained with an Olympus BX61 microscope equipped with an Olympus DP30BW camera. Olympus cellp imaging software or Olympus image-pro plus 6.0 software were used for imaging.