Escherichia coli and Salmonella Enteritidis dual-species biofilms: interspecies interactions and antibiofilm efficacy of phages

Abstract

Escherichia coli and Salmonella Enteritidis are foodborne pathogens forming challenging biofilms that contribute to their virulence, antimicrobial resistance, and survival on surfaces. Interspecies interactions occur between species in mixed biofilms promoting different outcomes to each species. Here we describe the interactions between E. coli and S. Enteritidis strains, and their control using specific phages. Single-species biofilms presented more cells compared to dual-species biofilms. The spatial organization of strains, observed by confocal microscopy, revealed similar arrangements in both single- and dual-species biofilms. The EPS matrix composition, assessed by Fourier-transform infrared spectroscopy, disclosed that the spectra extracted from the different dual-species biofilms can either be a combination of both species EPS matrix components or that the EPS matrix of one species predominates. Phages damaged more the single-species biofilms than the mixed biofilms, showing also that the killing efficacy was greatly dependent on the phage growth characteristics, bacterial growth parameters, and bacterial spatial distribution in biofilms. This combination of methodologies provides new knowledge of species-species and phage-host interactions in biofilms of these two major foodborne pathogens.

A Novel Tail-Associated O91-Specific Polysaccharide Depolymerase from a Podophage Reveals Lytic Efficacy of Shiga Toxin-Producing Escherichia coli

“…Antibiofilm activity assay. The effect of PHB19 and Dep6 on E. coli biofilms was assessed with 96-well microtiter plates or individual polystyrene plates as described previously (45)(46)(47). Briefly, E. coli biofilms were allowed to form in 96-well microtiter plates for 24 or 48 h at 37°C.…”

All Treatment Parameters Affect Environmental Surface Sanitation Efficacy, but Their Relative Importance Depends on the Microbial Target

“…Oxaran et al ( 27 ) interchanged L. monocytogenes and Staphylococcus aureus with each of their associated environmental spoilage microbiota communities and concluded that enhanced protection is caused by associations in the biofilm instead of specific characteristics of the pathogen. In addition, the decreased diffusion of antimicrobial agents through multilayer complex structures has been shown to contribute to the increased resistance ( 32 , 34 , 37 ). A dense structure of multiple heterogeneous layers of L. monocytogenes and Lactobacillus plantarum cells increased sanitizer tolerance of both species against benzalkonium chloride, but the protective effect was less pronounced against peracetic acid ( 38 ).…”

Phage JS02, A Putative Temperate Phage, A Novel Biofilm-Degrading Agent for Staphylococcus Aureus

“…For instance, similar to planktonic cells, the response of the bio lm to the phage was strain-dependent; the temperate phage ΦPan70 produced a reduction of 99.9% to ~ 99.999% depending on the strain [8]. Although the mechanism of phage-bio lm interaction is still unclear, it is believed that phage-derived enzymes degrade the major exopolysaccharide protective layer of the bio lm matrix, and consequently, phages can reach and kill bacterial cells in the bio lm [9]. Furthermore, phages can diffuse through the pores and channels in the bio lm to reach different layers of the bio lm [10].…”

“…For thermo-stability, the phage was incubated at 40 ºC, 50 ºC, 60 ºC, 70 ºC, and 80 ºC, and sample were collected after 20, 40, and 60 min for phage titration using the DLA method. For pH stability, the phage were added to tubes containing SM buffer of different pH values (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12) and then incubated for 1 h at 37 ºC before phage titration was performed by the DLA method [17].…”