Differential transcription of small RNAs and mRNAs of Streptococcus pneumoniae TIGR4 when grown with the biofilm inhibitor Carolacton

Carolacton is a novel biofilm inhibitor that kills biofilm cells of Streptococcus mutans in nanomolar concentrations. Interestingly, Carolacton also inhibits growth of the clinically relevant and human pathogenic bacterium Streptococcus pneumoniae TIGR4. The cellular target of Carolacton is still unknown. Here, we adressed the differential transcription of cellular RNAs when S. pneumoniae TIGR4 was grown in the presence of Carolacton. This was done to identify transcriptional regulatory networks that are directly affected by treatment of the pneumococcus with Carolacton. In order to gain insights into the primary transcriptional response, early time-points were chosen for sampling, which should not reflect secondary responses (e.g. due to differences in growth phase, drop in pH etc.). To achieve a thorough overview over all affected cellular RNA species, such as mRNAs, small regulatory RNAs and tRNAs, and not to lose small transcripts during library preparation, RNAs were separated according to size and used to construct two separate libraries for sequencing. Overall design: For each of the six examined time-points (0, 5, 15, 60, 120, 180 min), two biological replicates of Carolacton-treated and untreated samples were collected.