Investigating the effect of biofilm pathways on Bacillus subtilis anti-termination

Abstract

Biofilms are communities of bacteria ensconced in a blanket of exopolysaccharides and proteins. They can form in a variety of clinically important contexts such as the surfaces of teeth, contact lenses, and medical implants. Biofilm communities are more resistant to antibiotics than planktonic cells. Hence, it is important to understand the underlying mechanisms which promote biofilm formation. Bacillus subtilis is an important model system for studying biofilm-synthesis genes. The biosynthetic genes for B. subtilis exopolysaccharide are found in one, unusually long, operon (eps). A previously discovered processive anti-termination (PA) mechanism promotes readthrough of transcription termination sites within this operon. PA occurs when regulatory factor(s) modify the transcription elongation complex (TEC) such that it becomes resistant to downstream termination events. The PA mechanism of the eps operon requires a highly conserved RNA element called eps-associated RNA (EAR). It is not currently known how EAR exerts its influence on the TEC. The eps operon itself is only one of many biosynthetic genes necessary to biofilm formation and maintenance. In this study, we investigate the impact of a few key regulatory pathways on EAR anti-termination. We combined deletions of genes involved in these pathways with a genetic reporter assay for EAR anti-termination activity. Our preliminary data do not support a connection between these genes and the PA efficiency of EAR. These data suggest that anti-termination of the eps operon is not necessarily coupled to other known biofilm-regulatory pathways.