Comparison of gene expression profiles between static and shake culture in Rothia mucilaginosa

Abstract

Biofilm formation is an important virulence factor contributing to the chronicity and persistency of oral infections. Biofilms are formed by microbial cells embedded in exopolysac­ charides (EPS), which are a component of biofilm. We previously isolated EPS­producing Rothia mucilaginosa (strain DY­18) from a persistent apical periodontitis lesion. The aim of the present study was to identify genes relating to biofilm formation. High viscosity of spent culture medium obtained from static culture indicated that strain DY­18 produces large amounts of EPS and forms biofilms. In contrast, the low viscosity shown in shake culture was correlated with the planktonic mode of growth of this strain. Gene expression of strain DY­18 in the biofilm mode (static culture condition) was compared to that in the planktonic mode (shake culture condition) using microarray analysis. The results suggest that the genes encoding DNA polymerase Ⅲsubunit beta (gene tag :RMDY18_00020), signal transduction histidine kinase (RMDY18_00350), and molecular chaper­ one (RMDY18_16800) were significantly up­regulated in the biofilm mode. Bioinformatic analysis showed that RMDY18_16800 has domains relating to stress response, which has been shown to be a regulator of biofilm formation in other bacteria. The results suggest that these genes might contribute to EPS production and biofilm formation of strain DY­18.