Typhimurium encoded cold shock protein E is essential for motility and biofilm formation.

The ability of bacteria to form biofilms increases their survival under adverse environmental conditions. Biofilms have enormous medical and environmental impact; consequently, the factors that influence biofilm formation are an important area of study. In this investigation, the roles of two cold shock proteins (CSP) during biofilm formation were investigated in Typhimurium, which is a major foodborne pathogen. Among all CSP transcripts studied, the expression of (STM14_0732) was higher during biofilm growth. The deletion strain (Δ) did not form biofilms on a cholesterol coated glass surface; however, complementation with WT , but not the F30V mutant, was able to rescue this phenotype. Transcript levels of other CSPs demonstrated up-regulation of (STM14_4399) in Δ. The deletion strain (Δ) did not affect biofilm formation; however, ΔΔ exhibited higher biofilm formation compared to Δ. Most likely, the higher amounts in Δ reduced biofilm formation, which was corroborated using over-expression studies. Further functional studies revealed that Δ and ΔΔ exhibited slow swimming but no swarming motility. Although over-expression did not affect motility, complementation restored the swarming motility of Δ. The transcript levels of the major genes involved in motility in Δ demonstrated lower expression of the class III (, , ), but not class I () or class II (, ), flagellar regulon genes. Overall, this study has identified the interplay of two CSPs in regulating two biological processes: CspE is essential for motility in a CspA-independent manner whereas biofilm formation is CspA-dependent.