Streptococcus pneumoniae

Bistable switches are the key elements of the regulatory networks governing cell development, differentiation and life-strategy decisions. Transcriptional noise is a main determinant that causes switching between different states in bistable systems. By using the human pathogen Streptococcus pneumoniae as a model bacterium, we will investigate how transcriptional fidelity and processivity influence (noisy) gene expression and participate in bistability. To study this question, we will use both ...

Cells were grown to mid-exponential phase (OD600nm ~0.2) in GM17 medium at 37°C (with 0.15 mM ZnSO4 where relevant) and 84 ml of culture was mixed by inverting with 8.4 ml of fixing solution (50 mM Tris pH 8.0, 100 mM NaCl, 0.5 mM EGTA, 1 mM EDTA, 30% (v/v) formaldehyde) and incubated at room temperature for 30 min. Cells were disrupted and crosslinked DNA was sheared by sonication. Antibodies coupled to magnetic beads were used to pull down cross-linked complexes. DNA was purified, amplified, ...

1. Preparation of B. subtilis cultures

Inoculate cells from -80°C stocks in 10 ml time-lapse microscopy (TLM) medium (62 mM K2HPO4 , 44mM KH2PO4, 15 mM (NH4)2SO4, 6.5 mM sodium citrate, 0.8 mM MgSO4, 0.02 % casamino acids, 27.8 mM glucose, 0.1 mM L-tryptophan, the pH was set to 7 using a KOH solution) supplemented with antibiotics, if necessary. Grow the cells overnight in a shake flask (30°C, 225 rpm). The following morning, dilute the cells 1:10 in pre-warmed chemically defined medium (CDM) (62 ...