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Title: Microsensor and transcriptomic signatures of oxygen depletion in biofilms associated with chronic wounds: Biofilms and oxygen

Polymicrobial biofilms have been implicated in delayed wound healing, although the mechanisms by which biofilms impair wound healing are poorly understood. Many species of bacteria produce exotoxins and exoenzymes that may inhibit healing. In addition, oxygen consumption by biofilms may impede wound healing. In this study, we used oxygen microsensors to measure oxygen transects through in vitro-cultured biofilms, biofilms formed in vivo in a diabetic (db/db) mouse model, and ex vivo human chronic wound specimens. The results show that oxygen levels within both euthanized and live mouse wounds had steep gradients that reached minima ranging from 19 to 61% oxygen partial pressure, compared to atmospheric oxygen levels. The oxygen gradients in the mouse wounds were similar to those observed for clinical isolates cultured in vitro and for human ex vivo scabs. No oxygen gradients were observed for heat-killed scabs, suggesting that active metabolism by the viable bacteria contributed to the reduced oxygen partial pressure of the wounds. To characterize the metabolic activities of the bacteria in the mouse wounds, we performed transcriptomics analyses of Pseudomonas aeruginosa biofilms associated with the db/db mice wounds using Affymetrix microarrays. The results demonstrated that the bacteria expressed genes for metabolic activities associated with cellmore » growth. Interestingly, the transcriptome results indicated that the bacteria within the wounds also experienced oxygen-limitation stress. Among the bacterial genes that were expressed in vivo were genes associated with the Anr-mediated hypoxia-stress response. Other bacterial stress response genes highly expressed in vivo were genes associated with stationary-phase growth, osmotic stress, and RpoH-mediated heat shock stress. Overall, the results support the hypothesis that the metabolic activities of bacteria in biofilms act as oxygen sinks in chronic wounds and that the depletion of oxygen contributes to the detrimental impact of biofilms on wound healing.« less
Authors:
 [1] ;  [2] ;  [2] ;  [2] ;  [3] ;  [3] ;  [1] ;  [4] ;  [5] ;  [2] ;  [2] ;  [1] ;  [1] ;  [1]
  1. Center for Biofilm Engineering, Montana State University, Bozeman Montana
  2. Division of Dermatology, Department of Medicine, University of Washington, Seattle Washington
  3. The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman Washington
  4. Department of Microbiology and Molecular Genetics, 5180 Biomedical and Physical Sciences, Michigan State University, East Lansing Michigan
  5. Pacific Northwest National Laboratory, Chemical and Biological Signature Science, Richland Washington
Publication Date:
OSTI Identifier:
1255378
Report Number(s):
PNNL-SA-109039
Journal ID: ISSN 1067-1927
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Wound Repair and Regeneration; Journal Volume: 24; Journal Issue: 2
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
bacterial biofilms; chronic wound infections