Understanding the Role of Phosphodiesterase yhjH on Biofilm Formation in PHL628 E. coli

Biofilm serves as a protective mechanism against antimicrobial and disinfectant agents as a means to improve the bacteria's biological fitness. YhjH is a phosphodiesterase that degrades bis-(3’5’)-cyclic dimeric guanosine monophosphate (c-di-GMP) and has been shown to play a role in bacterial stress response by influencing biofilm formation. This temperature dependent phosphodiesterase plays a role in biofilm formation by impacting flagellar, curli, and type 1 pili synthesis via c-di-GMP level modulation. However, the exact mechanism involved in how yhjH impacts biofilm formation is still largely unknown. Here, we investigated how yhjH phosphodiesterase activity affects Escherichia coli biofilm formation by characterizing the influence of endogenous yhjH levels on biofilm formation in comparison to exogenously overexpressed yhjH. Using qPCR, immunoblotting techniques, and biofilm assays, yhjH phosphodiesterase activity was observed in E. coli strain PHL628 at 28 °C and 37 °C. Our initial findings indicate that at both the 48 hour and 72 hour time points biofilm concentration is greater in the bacteria grown in the absence of yhjH overexpression at 28 °C. At 37 °C, the bacteria at both time points with yhjH overexpression have a higher concentration of biofilm. By expanding our understanding of how yhjH phosphodiesterase affects biofilm formation, we could find more effective ways to treat diseases such as cystic fibrosis and Crohn's diseases that are caused by biofilm formation and current global health issues such as antibiotic resistance.