For every bacterial strain and negative control the cells of at least two wells of a six well tissue culture plaque were lysed and total RNA was isolated. Prior to lysis culture medium was aspirated and cells were lysed using RLT lysis buffer (Qiagen, Germany). Total RNA was isolated using the RNeasy Mini Kit and the RNase free DNase I set (Qiagen) following the manufacturers protocol. The RNA was recovered in RNase free water, heat denatured for 10 min. at 65uC; quantified with the NanoDropH ND-1000 UV-Vis Spectrophotometer (NanoDrop Technologies, USA) and a quality profile with the Agilent 2100 bioanalyzer (Agilent Technologies, Germany) was made.