Enterococcus faecalis thrives in dual-species biofilm models under iron-rich conditions

Abstract

Escherichia coli (E. coli) and Enterococcus faecalis (E. faecalis) are pathogenic strains that often coexist as an intestinal ora in humans and are prone to cause bio lm-associated infections such as gastrointestinal tract and urinary tract infections. Earlier studies have demonstrated that E. faecalis bio lm can metabolize ferrous ions in iron-rich environments and promote bio lm growth under in-vivo conditions. However, the in uence of iron transporters on dual-species bio lm growth and the nature of molecular-level interactions between iron transporter proteins and Fe 2+ remains unknown. Therefore, we performed co-culture studies and found that Fe 2+ at concentrations of 50 to 150 µM promotes the colonization of E. coli, and Fe 2+ concentrations of 50 to 200 µM promote the growth of E. faecalis and dual-species colonies. Similarly, Fe 2+ at concentrations of 50 to 250 µM promotes E. coli and E. faecalis bio lm formation 50 to 300 µM promotes bio lm formation of dual-species bio lms. Atomic absorption spectroscopy results reveal that Fe 2+ ion augmentation in bacterial cells was increased to 4 folds in the single-species model and 11 folds in the dual-species model under iron-supplemented conditions. Furthermore, Fe 2+ augmentation increased the antibiotic resistance of E. faecalis in both single and dualspecies bacterial cultures. In addition, we have performed in-silico studies to determine a threedimensional (3D) structure of ferrous iron-transporter proteins FeoB of E. faecalis and its a nity to extracellular Fe 2+ . Our model suggests that the FeoB facilitates the Fe 2+ uptake in E. faecalis cells in the absence of iron chelator, 2,2-bipyridyl.

Phage SPO1 Protein Gp49 Is a Novel RNA Binding Protein That Is Involved in Host Iron Metabolism

“…This could be explained in that Gp49 does not have RNase activity and its RNA binding ability may stabilize, thus upregulate the genes in the hem operon. A recent study showed that the Gram-positive bacterium Enterococcus faecalis ( E. faecalis ) was stained safranin color instead of violet during Gram staining in the iron-supplemented condition (300 μM) [ 20 ]. The 11-fold increase of iron storage in bacterial cells reported in the study is consistent with our observation in the Gp49 overexpressing B. subtilis .…”

Comparative proteomics analysis of biofilms and planktonic cells of Enterococcus faecalis and Staphylococcus lugdunensis with contrasting biofilm-forming ability

“…In E . faecalis , FeoB has been reported to promote biofilm formation and antibiotic resistance by potentially binding and importing Fe2+ into the cytosol [ 38 ]. On the other hand, the presence and biological role of ferrous iron transport protein in S .…”

“…Ferrous iron transport protein is a membrane protein that is essential for Fe (II) uptake in bacteria [37]. In E. faecalis, FeoB has been reported to promote biofilm formation and antibiotic resistance by potentially binding and importing Fe2+ into the cytosol [38]. On the other hand, the presence and biological role of ferrous iron transport protein in S. lugdunensis has not yet been clearly determined, other than a previous study that found that the deletion of accessory gene regulator (agr) involved in quorum sensing upregulated ferrous iron transport protein B [39], indicating a potential involvement in biofilm formation.…”

A review on antimicrobial strategies in mitigating biofilm-associated infections on medical implants

“…UTIs are caused by Gram-positive bacteria (e.g., E. faecalis, S. aureus , group B Streptococcus (GBS)), Gram-negative bacteria (e.g., E. coli, K. Pneumonia, Proteus mirabilis ( P. Mirabilis ) , P. aeruginosa ), as well as some fungal species (e.g., Candida spp.) ( Flores-Mireles et al, 2015 ; Govindarajan et al, 2022 ; Jacobsen and Shirtliff, 2011 ). UTI starts when uropathogens from the gut or bacteria from the skin around the urethral opening migrate to the urethra and then progress to the bladder.…”