Fig. 2. Extracellular RNA is present in the Staphylococcus aureus biofilm matrix.

a A biofilm matrix extracted from 24-h biofilms of MR10 was treated with the indicated enzymes or left untreated (Control); nucleic acids were separated on agarose gels. b RNA size was estimated using urea-denaturing polyacrylamide gel electrophoresis. The sample after treatment with RNase A was also loaded as a control. c MR10 biofilms formed at the indicated time points (hours) were treated with RNase A (gray bars) or left untreated (white bars) with RNase A. The data are presented as the mean and standard deviation (error bar) of three independent experiments. **P < 0.01. d A biofilm matrix was isolated from the biofilms at the indicated time points (hours) and the presence of nucleic acids was determined using agarose gel electrophoresis. The applied volume was standardized by biofilm wet weight (10 μL of the biofilm matrix extracted from 0.44 mg of the biofilm was applied per one lane). The white and black arrowheads denote RNA and DNA, respectively.