Staphylococcus aureus utilizes environmental RNA as a building material in specific polysaccharide-dependent biofilms

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• Biofilms are microbial communities causing chronic infections.
• Extracellular DNA is vital for biofilm development.
• The role of extracellular RNA in biofilms is largely unknown.

Purpose of the Study:

• To investigate the role of extracellular RNA in Staphylococcus aureus biofilm formation and structural integrity.
• To identify the source and function of RNA within the biofilm matrix.
• To elucidate the mechanisms by which RNA contributes to biofilm organization.

Main Methods:

• Enzymatic degradation of RNA using RNase A to assess biofilm dispersal.
• RNA sequencing to identify RNA sources in the biofilm matrix.
• Microscopy and molecular interaction analyses to study RNA-polysaccharide interactions.

Main Results:

• RNase A treatment dispersed both fresh and mature Staphylococcus aureus biofilms.
• The Brain Heart Infusion medium was identified as the primary source (>99.32%) of extracellular RNA in biofilms.
• External RNA purified from the medium significantly promoted biofilm formation.
• Polysaccharides were found to be critical for capturing and stabilizing external RNA within biofilms.

Conclusions:

• Extracellular RNA plays a significant role in the structural integrity and organization of Staphylococcus aureus biofilms.
• Bacterial biofilms can effectively capture and utilize external RNA, with polysaccharides mediating this interaction.
• These findings highlight the importance of externally derived substances in bacterial biofilm development and organization, opening new avenues for therapeutic strategies.