AUTHOR=Aljohani Ahmad M. , El-Chami Cecile , Alhubail Muna , Ledder Ruth G. , O’Neill Catherine A. , McBain Andrew J. 

TITLE=Escherichia coli Nissle 1917 inhibits biofilm formation and mitigates virulence in Pseudomonas aeruginosa

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1108273

DOI=10.3389/fmicb.2023.1108273

ISSN=1664-302X

ABSTRACT=<p>In the quest for mitigators of bacterial virulence, cell-free supernatants (CFS) from 25 human commensal and associated bacteria were tested for activity against <italic>Pseudomonas aeruginosa</italic>. Among these, <italic>Escherichia coli</italic> Nissle 1917 CFS significantly inhibited biofilm formation and dispersed extant pseudomonas biofilms without inhibiting planktonic bacterial growth. eDNA was reduced in biofilms following exposure to <italic>E. coli</italic> Nissle CFS, as visualized by confocal microscopy. <italic>E. coli</italic> Nissle CFS also showed a significant protective effect in a <italic>Galleria mellonella</italic>-based larval virulence assay when administrated 24 h before challenge with the <italic>P. aeruginosa.</italic> No inhibitory effects against <italic>P. aeruginosa</italic> were observed for other tested <italic>E. coli</italic> strains. According to proteomic analysis, <italic>E. coli</italic> Nissle CFS downregulated the expression of several <italic>P. aeruginosa</italic> proteins involved in motility (Flagellar secretion chaperone FliSB, B-type flagellin fliC, Type IV pilus assembly ATPase PilB), and quorum sensing (acyl-homoserine lactone synthase lasI and HTH-type quorum-sensing regulator rhlR), which are associated with biofilm formation. Physicochemical characterization of the putative antibiofilm compound(s) indicates the involvement of heat-labile proteinaceous factors of greater than 30 kDa molecular size.</p>