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Optical O₂ Sensors Also Respond to Redox Active Molecules Commonly Secreted by Bacteria

Flamholz, Avi I. and Saccomano, Samuel and Cash, Kevin and Newman, Dianne K. (2022) Optical O₂ Sensors Also Respond to Redox Active Molecules Commonly Secreted by Bacteria. mBio, 13 (6). Art. No. e02076-22. ISSN 2150-7511. doi:10.1128/mbio.02076-22. https://resolver.caltech.edu/CaltechAUTHORS:20221117-155838300.12

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Abstract

From a metabolic perspective, molecular oxygen (O₂) is arguably the most significant constituent of Earth’s atmosphere. Nearly every facet of microbial physiology is sensitive to the presence and concentration of O₂, which is the most favorable terminal electron acceptor used by organisms and also a dangerously reactive oxidant. As O₂ has such sweeping implications for physiology, researchers have developed diverse approaches to measure O₂ concentrations in natural and laboratory settings. Recent improvements to phosphorescent O₂ sensors piqued our interest due to the promise of optical measurement of spatiotemporal O₂ dynamics. However, we found that our preferred bacterial model, Pseudomonas aeruginosa PA14, secretes more than one molecule that quenches such sensors, complicating O₂ measurements in PA14 cultures and biofilms. Assaying supernatants from cultures of 9 bacterial species demonstrated that this phenotype is common: all supernatants quenched a soluble O₂ probe substantially. Phosphorescent O₂ probes are often embedded in solid support for protection, but an embedded probe called O₂NS was quenched by most supernatants as well. Measurements using pure compounds indicated that quenching is due to interactions with redox-active small molecules, including phenazines and flavins. Uncharged and weakly polar molecules like pyocyanin were especially potent quenchers of O₂NS. These findings underscore that optical O₂ measurements made in the presence of bacteria should be carefully controlled to ensure that O₂, and not bacterial secretions, is measured, and motivate the design of custom O₂ probes for specific organisms to circumvent sensitivity to redox-active metabolites.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1128/mbio.02076-22DOIArticle
https://resolver.caltech.edu/CaltechAUTHORS:20220810-751722000Related ItemDiscussion Paper
ORCID:
AuthorORCID
Flamholz, Avi I.0000-0002-9278-5479
Saccomano, Samuel0000-0001-9105-2663
Cash, Kevin0000-0002-9748-2530
Newman, Dianne K.0000-0003-1647-1918
Additional Information:Thanks to Chelsey VanDrisse for supplying pyocyanin, Andrew Babbin for OXNANO beads, Lucas Meirelles and John Ciemniecki for assistance with toxoflavin and B. glumae cultivation. Thanks to Josh Goldford, Darcy McRose, Georgia Squyers, Lev Tsypin, and Shuangning Xu for useful conversations. This investigation was aided by a Postdoctoral Fellowship from The Jane Coffin Childs Memorial Fund for Medical Research (to A.I.F.) and NIH grants (1R01AI127850-01A1 and 1R01HL152190-01) to D.K.N. as well as the US Department of Energy (DOE) Office of Science, Office of Biological and Environmental Research Bioimaging Science Program under subcontract B643823 (to K.C.) and the LLNL 3DQ Microscope Project, SCW1713.
Group:Division of Geological and Planetary Sciences
Funders:
Funding AgencyGrant Number
Jane Coffin Childs Memorial Fund for Medical ResearchUNSPECIFIED
NIH1R01AI127850-01A1
NIH1R01HL152190-01
Department of Energy (DOE)B643823
Department of Energy (DOE)SCW1713
Issue or Number:6
DOI:10.1128/mbio.02076-22
Record Number:CaltechAUTHORS:20221117-155838300.12
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20221117-155838300.12
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:117907
Collection:CaltechAUTHORS
Deposited By: Research Services Depository
Deposited On:30 Nov 2022 18:42
Last Modified:25 Jan 2023 22:56

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