design: Total RNA was extracted from bacterial cells lysed with 3 mg/ml lysozyme (Roche Diagnostic, Mannheim, Germany) and 0.4 mg/ml proteinase K (Ambion, Carlsbad, CA, United States) prepared in TE buffer (10 mM Tris-HCl; 1 mM ethylenediaminetetraacetic acid [EDTA], pH 8.0). RNeasy Mini Kit (Qiagen, Hilden, Germany) was used for RNA extraction, performing on-column DNase digestion with the RNAse-free DNase set (Qiagen, Hilden, Germany), as per manufacturers instructions. RNA libraries for RNA-seq were prepared by Novogene following Novogene's standard protocols.