Oxygen tolerance estimates in Campylobacter species depend on the testing medium

Area of Science:

• Microbiology
• Bacterial Physiology
• Oxygen Tolerance

Background:

• Microaerophilic bacteria, such as Campylobacter jejuni subsp. jejuni, have specific oxygen requirements.
• Complex media composition, particularly the tryptone component, can influence the observed oxygen tolerance of these bacteria.
• Understanding oxygen tolerance is crucial for Campylobacter cultivation and research.

Purpose of the Study:

• To investigate the impact of different complex media on the oxygen tolerance of Campylobacter jejuni subsp. jejuni.
• To determine the oxygen tolerance of various Campylobacter species using a chemically-defined medium.
• To evaluate the effect of reactive oxygen intermediate scavengers on Campylobacter oxygen tolerance.

Main Methods:

• Culturing Campylobacter jejuni subsp. jejuni on complex media with varying oxygen levels.
• Utilizing a chemically-defined, agar-solidified medium for precise oxygen tolerance assessment.
• Supplementing the defined medium with various scavengers of reactive oxygen intermediates.

Main Results:

• Oxygen tolerance of Campylobacter jejuni subsp. jejuni was significantly influenced by the brand and tryptone content of complex media.
• Growth was observed at 21% oxygen with some tryptones, but not with others at 15% oxygen or higher.
• A chemically-defined medium allowed for oxygen tolerance assessment of Campylobacter jejuni subsp. jejuni, Campylobacter coli, and Campylobacter fetus subsp. fetus.
• Scavengers like allopurinol, azelaic acid, caffeine, cimetidine, TEMPOL, and pyruvate markedly enhanced oxygen tolerance.

Conclusions:

• The composition of growth media critically affects the apparent oxygen tolerance of Campylobacter species.
• Chemically-defined media provide a more reliable system for studying oxygen tolerance.
• Specific reactive oxygen species scavengers can significantly improve the survival of Campylobacter under oxygen stress.