Summary of Study ST002277

This data is available at the NIH Common Fund's National Metabolomics Data Repository (NMDR) website, the Metabolomics Workbench, https://www.metabolomicsworkbench.org, where it has been assigned Project ID PR001458. The data can be accessed directly via it's Project DOI: 10.21228/M8898H This work is supported by NIH grant, U2C- DK119886.

See: https://www.metabolomicsworkbench.org/about/howtocite.php

This study contains a large results data set and is not available in the mwTab file. It is only available for download via FTP as data file(s) here.

Study ID	ST002277
Study Title	Skin-to-blood pH shift triggers metabolome and proteome global remodelling in Staphylococcus epidermidis
Study Type	NMR Metabolomics combine with proteomics to study pH adaptation of Staphylococcus epidermidis 19N
Study Summary	Staphylococcus epidermidis (SE) is one of the most common bacteria of the human skin microbiota. Despite its role as a commensal, SE has emerged as an opportunistic pathogen, associated with 80% of medical devices related infections. Moreover, these bacteria are extremely difficult to treat due to their ability to form biofilms and accumulate resistance to almost all classes of antimicrobials developed so far. Thus new preventive and therapeutic strategies are urgently needed. In spite of its clinical importance, the molecular mechanisms associated with SE colonisation and disease are still poorly understood. A deeper understanding of the metabolic and cellular processes associated with response to environmental factors characteristic of SE ecological niches in health and disease might provide new clues on colonisation and disease processes. Here we studied the impact of pH conditions, mimicking the skin pH (5.5) and blood pH (7.4), in a S. epidermidis commensal strain, belonging to the B clonal lineage, by means of next-generation proteomics and 1H NMR-based metabolomics. Moreover, we evaluated the metabolic changes occurring when a sudden pH change arise, simulating the skin barrier break produced by a catheter. We found that exposure of S. epidermidis to skin pH induced oxidative phosphorylation and biosynthesis of peptidoglycan, lipoteichoic acids and betaine. In contrast, at blood pH, the incorporation of monosaccharides and its oxidation by glycolysis and fermentation was promoted. Additionally, several proteins related to virulence and immune evasion, namely extracellular proteases and membrane iron transporters were more abundant at blood pH. In the situation of an abrupt skin-to-blood pH shift we observed the decrease in the osmolyte betaine and changes in the levels of several metabolites and proteins involved in redox cell homeostasis. Our results suggest that at the skin pH S. epidermidis cells are metabolically more active and adhesion is promoted, while at blood pH, metabolism is tuned down and cells have a more virulent profile. pH increase during commensal-to-pathogen conversion appears to be a critical environmental signal to the remodelling of the S. epidermidis metabolism towards a more pathogenic state. Targeting S. epidermidis proteins induced by a low alkaline pH and local acidification of medical devices microenvironment might be new strategies to treat and prevent S. epidermidis infections.
Institute	ITQB NOVA
Laboratory	Proteomics of Non-Model Organisms
Last Name	Gonçalves
First Name	Luís
Address	Avenida Republica, Oeiras, Not USCanada, 2780-157 Oeiras, Portugal
Email	lgafeira@itqb.unl.pt
Phone	214469464
Submit Date	2022-07-14
Num Groups	3
Raw Data Available	Yes
Raw Data File Type(s)	fid
Analysis Type Detail	NMR
Release Date	2023-01-16
Release Version	1

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Treatment:

Treatment ID:	TR002375
Treatment Summary:	In this work, three pH transitions from pre-inoculum to inoculum were assayed. S. epidermidis pre-inoculums and the growth were performed at medium with pH 7.4, to mimic the blood pH; and pH 5.5, to mimic the skin pH. The pre-inoculum cellular density was adjusted to 0.06 (OD600) (aprox.1.5x108 CFU/mL) and used to inoculate fresh medium in the three conditions depicted in Figure 1, simulating S. epidermidis at skin and blood and a pH shock endured by S. epidermidis during the infection process from skin to blood transition. The cell cultures incubated at 37ºC with 225 rpm were followed by OD600 and recovered at mid-exponential phase for further analysis. Pre-inocula were prepared in TSB medium at pH 5.5 or 7.4. Inocula at pH 5.5 was used for the cultures grown at 5.5 (N55) and 7.4 (N57), and the inoculum at pH 7.4 for the culture at the same pH (N77). The cells were harvested at mid-exponential phase.

Treatment ID:

TR002375

Treatment Summary:

In this work, three pH transitions from pre-inoculum to inoculum were assayed. S. epidermidis pre-inoculums and the growth were performed at medium with pH 7.4, to mimic the blood pH; and pH 5.5, to mimic the skin pH. The pre-inoculum cellular density was adjusted to 0.06 (OD600) (aprox.1.5x108 CFU/mL) and used to inoculate fresh medium in the three conditions depicted in Figure 1, simulating S. epidermidis at skin and blood and a pH shock endured by S. epidermidis during the infection process from skin to blood transition. The cell cultures incubated at 37ºC with 225 rpm were followed by OD600 and recovered at mid-exponential phase for further analysis. Pre-inocula were prepared in TSB medium at pH 5.5 or 7.4. Inocula at pH 5.5 was used for the cultures grown at 5.5 (N55) and 7.4 (N57), and the inoculum at pH 7.4 for the culture at the same pH (N77). The cells were harvested at mid-exponential phase.