<i>Enterococcus faecalis</i> inhibits <i>Klebsiella pneumoniae</i> growth in polymicrobial biofilms in a glucose-enriched medium

Ballén, Victoria; Ratia, Carlos; Cepas, Virginio; Soto, Sara M.

doi:10.1080/08927014.2020.1824272

Cited by 14 publications

(14 citation statements)

References 49 publications

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“…This is not surprising as P. aeruginosa growth is generally affected at low pH and P. aeruginosa prefers to grow in a more neutral pH range (82, 83). In fact, E. faecalis V583 adopts a similar strategy of lowering environmental pH as a result of lactic acid export to inhibit Klebsiella pneumoniae growth in polymicrobial biofilms (84). Even though a P. aeruginosa PADP6 strain that is able to grow in iron-restricted conditions is used to study the polymicrobial interactions with E. faecalis , the lowered iron availability resulted from 22D-mediated iron chelation and L-lactate-mediated iron chelation is likely an added stress apart from the lowered pH environment.…”

Section: Discussionmentioning

confidence: 99%

Enterococcus faecalis antagonizes Pseudomonas aeruginosa growth in polymicrobial biofilms

Tan

Lam

Biuković

et al. 2022

Preprint

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Enterococcus faecalis is often co-isolated with Pseudomonas aeruginosa in polymicrobial biofilm-associated infections of wounds and the urinary tract. As a defense strategy, the host innately restricts iron availability at infection sites. Despite their co-prevalence, the polymicrobial interactions of these two pathogens in iron-restricted conditions, such as those found in the host, remains unexplored. Here we show that E. faecalis inhibits P. aeruginosa growth within biofilms when iron is restricted. E. faecalis lactate dehydrogenase (ldh1) gives rise to L-lactate production during fermentative growth. We find that E. faecalis ldh1 mutant fails to inhibit P. aeruginosa growth. Additionally, we demonstrate that ldh1 expression is induced in iron-restricted conditions, resulting in increased lactic acid exported and consequently, a reduction in pH. Together, our results suggest that E. faecalis synergistically inhibit P. aeruginosa growth by decreasing environmental pH and L-lactate-mediated iron chelation. Overall, this study highlights that the microenvironment in which the infection occurs is important for understanding its pathophysiology.

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Section: Discussionmentioning

confidence: 99%

Enterococcus faecalis antagonizes Pseudomonas aeruginosa growth in polymicrobial biofilms

Tan

Lam

Biuković

et al. 2022

Preprint

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“…faecalis manifests amensalism by using an altered metabolic path which produces lactic acid and inhibits the growth of K . pneumonia (Ballén et al, 2020). Despite several opportunistic strategies adapted by this bacterium in the enriched medium, it needs to be explored whether the organism can overcome the stress of magnetic field.…”

Section: Discussionmentioning

confidence: 99%

“…The bacterial strain can also bind to the substrate dentine and can penetrate the dental tubules (Evans et al, 2002). As a survival strategy in the glucose enriched medium, E. faecalis manifests amensalism by using an altered metabolic path which produces lactic acid and inhibits the growth of K. pneumonia (Ballén et al, 2020). Despite several opportunistic strategies adapted by this bacterium in the enriched medium, it needs to be explored whether the organism can overcome the stress of magnetic field.…”

Section: Discussionmentioning

confidence: 99%

Dosimetry of pulsed magnetic field towards attaining bacteriostatic effect on Enterococcus faecalis: Implications for endodontic therapy

et al. 2021

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Aim To examine in a laboratory setting the efficacy of moderate to high strength magnetic fields, as a potential bacteriostatic stimulus, against Enterococcus faecalis, one of the causative agents for infection during root canal treatments. Methodology Four different strengths (1, 2, 3 and 4 T) of the pulsed magnetic field (PMF) were applied in thirty repetitions to bacterial suspension. A pickup coil setup was used to measure the electromotive force induced inside the bacterial suspensions. The optical density (OD) was monitored over time (for 16 h 40 min) during the post‐treatment period to assess bacterial growth. Along with the change in OD values, live/dead assay, membrane depolarization study, atomic force microscopy (AFM), scanning electron microscopy (SEM) and reactive oxygen species (ROS) assay on selected samples were studied to evaluate the effect of PMFs. All results were analysed using one‐way ANOVA followed by post hoc Tukey test and considered significant at p < .05. Regression analysis (at a confidence of 95%, α = 0.05) was performed on the bacterial growth and membrane depolarization studies to determine progressive changes of the outcomes. Results The peak value of the induced electromotive force was recorded as 0.25 V, for the 4 T magnetic field pulse with a pulse width of 16 ms. There was a significant arrest of bacterial cell growth after an exposure to PMFs of 1 T, 3 T and 4 T (ANOVA score: F (4, 495) =395.180 at p = .05). The image‐based qualitative results of the live/dead assay using fluorescence microscopy techniques indicated that an exposure to higher PMFs (3 T/ 4 T) induced a bacteriostatic effect in a longer post‐exposure timescale. Evidence of altered membrane potential within the 2 h of exposure to 4 T PMF was supported by the incidence of elevated ROS. For the ROS assay, a significant difference occurred for 4 T exposed samples (ANOVA score: calculated F (1, 3) =20.2749 at p = .05). SEM and AFM observations corroborated with the outcomes, by portraying significant membrane damage. Conclusion In a laboratory setting, PMFs with higher magnitudes (3 T and 4 T) were capable of inducing bacteriostatic effects on E. faecalis.

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“…These combined efforts will piece together the biological mechanisms that drive biofouling over membranes, knowledge ultimately useful for developing economical and sustainable membrane-based bioseparation processes. Beyond membrane biofouling, the PSD approach also has broader implications for understanding the spatiotemporal development of early biofilms over a variety of other synthetic material interfaces such as urinary catheter surfaces, where multispecies biofilm assembly ultimately leads to catheter-associated urinary tract infections. − …”

Section: Discussionmentioning

confidence: 99%

Polymer Surface Dissection for Correlated Microscopic and Compositional Analysis of Bacterial Aggregates during Membrane Biofouling

Masigol

Radaha

Kannan

et al. 2021

ACS Appl. Bio Mater.

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Multispecies biofilms are a common limitation in membrane bioreactors, causing membrane clogging, degradation, and failure. There is a poor understanding of biological fouling mechanisms in these systems due to the limited number of experimental techniques useful for probing microbial interactions at the membrane interface. Here, we develop a new experimental method, termed polymer surface dissection (PSD), to investigate multispecies assembly processes over membrane surfaces. The PSD method uses photodegradable polyethylene glycol hydrogels functionalized with bioaffinity ligands to bind and detach microscale, microbial aggregates from the membrane for microscopic observation. Subsequent exposure of the hydrogel to high resolution, patterned UV light allows for controlled release of any selected aggregate of desired size at high purity for DNA extraction. Follow-up 16S community analysis reveals aggregate composition, correlating microscopic images with the bacterial community structure. The optimized approach can isolate aggregates with microscale spatial precision and yields genomic DNA at sufficient quantity and quality for sequencing from aggregates with areas as low as 2000 μm2, without the need of culturing for sample enrichment. To demonstrate the value of the approach, PSD was used to reveal the composition of microscale aggregates of different sizes during early-stage biofouling of aerobic wastewater communities over PVDF membranes. Larger aggregates exhibited lower diversity of bacterial communities, and a shift in the community structure was found as aggregate size increased to areas between 25,000 and 45,000 μm2, below which aggregates were more enriched in Bacteroidetes and above which aggregates were more enriched with Proteobacteria. The findings demonstrate that community succession can be observed within microscale aggregates and that the PSD method is useful for identification and characterization of early colonizing bacteria that drive biofouling on membrane surfaces.

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Enterococcus faecalis inhibits Klebsiella pneumoniae growth in polymicrobial biofilms in a glucose-enriched medium

Cited by 14 publications

References 49 publications

Enterococcus faecalis antagonizes Pseudomonas aeruginosa growth in polymicrobial biofilms

Enterococcus faecalis antagonizes Pseudomonas aeruginosa growth in polymicrobial biofilms

Dosimetry of pulsed magnetic field towards attaining bacteriostatic effect on Enterococcus faecalis: Implications for endodontic therapy

Polymer Surface Dissection for Correlated Microscopic and Compositional Analysis of Bacterial Aggregates during Membrane Biofouling

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