Autofluorescence properties of wound-associated bacteria cultured under various temperature, salinity, and pH conditions
Abstract Background Bacterial autofluorescence plays a vital role in photodiagnosis (PD) and antimicrobial photodynamic therapy (aPDT), yet the autofluorescence properties of wound-associated bacteria and their responses to the physicochemical microenvironment, remain underexplored. Here, we investi...
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BMC
2025-08-01
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| Online Access: | https://doi.org/10.1186/s12866-025-04200-3 |
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| author | Xiaofen Sun Yikun Wang Ao Du Meili Dong Yuhan Wang Yuanzhi Zhang Yang Zhang Yao Huang Xiang Huang Yong Liu Jingshu Ni |
| author_facet | Xiaofen Sun Yikun Wang Ao Du Meili Dong Yuhan Wang Yuanzhi Zhang Yang Zhang Yao Huang Xiang Huang Yong Liu Jingshu Ni |
| author_sort | Xiaofen Sun |
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| description | Abstract Background Bacterial autofluorescence plays a vital role in photodiagnosis (PD) and antimicrobial photodynamic therapy (aPDT), yet the autofluorescence properties of wound-associated bacteria and their responses to the physicochemical microenvironment, remain underexplored. Here, we investigated the bacterial autofluorescence of Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus under various culture conditions, including different temperatures, NaCl concentrations, and pH levels found within wounds. Fluorescence imaging was employed to quantify red fluorescence intensity, while fluorescence spectrometry was used to correlate the observed fluorescence with spectral profiles, benchmarking them against coproporphyrin and protoporphyrin IX. Results Our results revealed that the selected bacteria emitted red fluorescence in vitro, consistent with their known porphyrin biosynthesis capabilities. The intensity of red fluorescence was primarily dependent on the bacterial species, growth phase, and culture conditions. Elevated culture temperature accelerated the fluorescence metabolism, whereas increasing NaCl concentrations and alkaline pH levels inhibited red fluorescence in a dose-dependent manner. Linear regression revealed a strong positive correlation between red fluorescence intensity and peak fluorescence emission when excited at 405 nm. The biosynthesis of endogenous porphyrins varied both across and within bacterial species, with distinct porphyrins produced under specific conditions. The emission spectra of the gram-positive S. aureus consistently aligned with coproporphyrin, while the gram-negative A. baumannii, E. coli, and K. pneumoniae typically displayed fluorescence peaks characteristic of protoporphyrin IX. Notably, K. pneumoniae shifted to coproporphyrin with extended culture duration or more favourable conditions, and E. coli exhibited a similar transition as the pH increased to 9. Conclusions We concluded that the local physicochemical conditions found within wounds could affect the autofluorescence and endogenous porphyrins of the bacteria, which may, in turn, have connotations for PD and aPDT. |
| format | Article |
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| institution | Kabale University |
| issn | 1471-2180 |
| language | English |
| publishDate | 2025-08-01 |
| publisher | BMC |
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| series | BMC Microbiology |
| spelling | doaj-art-4c9783f0bf1c41419bbe88634ffb1e3a2025-08-20T03:42:23ZengBMCBMC Microbiology1471-21802025-08-0125111710.1186/s12866-025-04200-3Autofluorescence properties of wound-associated bacteria cultured under various temperature, salinity, and pH conditionsXiaofen Sun0Yikun Wang1Ao Du2Meili Dong3Yuhan Wang4Yuanzhi Zhang5Yang Zhang6Yao Huang7Xiang Huang8Yong Liu9Jingshu Ni10Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of SciencesAnhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of SciencesAnhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of SciencesAnhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of SciencesAnhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of SciencesAnhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of SciencesAnhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of SciencesAnhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of SciencesDepartment of Anesthesiology, Division of Life Sciences and Medicine, First Affiliated Hospital of USTC, University of Science and Technology of ChinaAnhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of SciencesAnhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of SciencesAbstract Background Bacterial autofluorescence plays a vital role in photodiagnosis (PD) and antimicrobial photodynamic therapy (aPDT), yet the autofluorescence properties of wound-associated bacteria and their responses to the physicochemical microenvironment, remain underexplored. Here, we investigated the bacterial autofluorescence of Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus under various culture conditions, including different temperatures, NaCl concentrations, and pH levels found within wounds. Fluorescence imaging was employed to quantify red fluorescence intensity, while fluorescence spectrometry was used to correlate the observed fluorescence with spectral profiles, benchmarking them against coproporphyrin and protoporphyrin IX. Results Our results revealed that the selected bacteria emitted red fluorescence in vitro, consistent with their known porphyrin biosynthesis capabilities. The intensity of red fluorescence was primarily dependent on the bacterial species, growth phase, and culture conditions. Elevated culture temperature accelerated the fluorescence metabolism, whereas increasing NaCl concentrations and alkaline pH levels inhibited red fluorescence in a dose-dependent manner. Linear regression revealed a strong positive correlation between red fluorescence intensity and peak fluorescence emission when excited at 405 nm. The biosynthesis of endogenous porphyrins varied both across and within bacterial species, with distinct porphyrins produced under specific conditions. The emission spectra of the gram-positive S. aureus consistently aligned with coproporphyrin, while the gram-negative A. baumannii, E. coli, and K. pneumoniae typically displayed fluorescence peaks characteristic of protoporphyrin IX. Notably, K. pneumoniae shifted to coproporphyrin with extended culture duration or more favourable conditions, and E. coli exhibited a similar transition as the pH increased to 9. Conclusions We concluded that the local physicochemical conditions found within wounds could affect the autofluorescence and endogenous porphyrins of the bacteria, which may, in turn, have connotations for PD and aPDT.https://doi.org/10.1186/s12866-025-04200-3Bacterial autofluorescenceEndogenous porphyrinsTemperatureNaCl concentrationpH |
| spellingShingle | Xiaofen Sun Yikun Wang Ao Du Meili Dong Yuhan Wang Yuanzhi Zhang Yang Zhang Yao Huang Xiang Huang Yong Liu Jingshu Ni Autofluorescence properties of wound-associated bacteria cultured under various temperature, salinity, and pH conditions BMC Microbiology Bacterial autofluorescence Endogenous porphyrins Temperature NaCl concentration pH |
| title | Autofluorescence properties of wound-associated bacteria cultured under various temperature, salinity, and pH conditions |
| title_full | Autofluorescence properties of wound-associated bacteria cultured under various temperature, salinity, and pH conditions |
| title_fullStr | Autofluorescence properties of wound-associated bacteria cultured under various temperature, salinity, and pH conditions |
| title_full_unstemmed | Autofluorescence properties of wound-associated bacteria cultured under various temperature, salinity, and pH conditions |
| title_short | Autofluorescence properties of wound-associated bacteria cultured under various temperature, salinity, and pH conditions |
| title_sort | autofluorescence properties of wound associated bacteria cultured under various temperature salinity and ph conditions |
| topic | Bacterial autofluorescence Endogenous porphyrins Temperature NaCl concentration pH |
| url | https://doi.org/10.1186/s12866-025-04200-3 |
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