Development and use of a chemically defined medium for estimating the oxygen tolerance of campylobacter species
When estimating the degree of oxygen tolerance of Campylobacter spp. on Brucella medium, the brand of tryptone (pancreatic digest of casein) used in the medium greatly influenced the results. In fact, with some brands and batches of tryptone, C. jejuni could grow at 21 % 02 without any additional sc...
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| Format: | Others |
| Language: | en |
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Virginia Tech
2014
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| Online Access: | http://hdl.handle.net/10919/41342 http://scholar.lib.vt.edu/theses/available/etd-03032009-040333/ |
| Summary: | When estimating the degree of oxygen tolerance of Campylobacter spp. on Brucella
medium, the brand of tryptone (pancreatic digest of casein) used in the medium greatly influenced
the results. In fact, with some brands and batches of tryptone, C. jejuni could grow at 21 % 02
without any additional scavengers of reactive oxygen intermediates (ROIs), although C02 was still
required for growth. When the medium was prepared with other brands of tryptone, it did not allow
growth of C. jejuni beyond 10% 02. The dependence of the growth response on different types and
brands of tryptone-based media makes it impossible to achieve reproducibility in oxygen tolerance
studies.
<p>To eliminate such variation in complex media, we developed a chemically defined medium
for Campylobacter spp. This medium allows reproducible colony counts to be obtained. The
medium was used to assess the effect of ROI scavengers on the oxygen tolerance of various
Campylobacter species. Allopurinol, azelaic acid, caffeine, cimetidine, and pyruvate when used
singly were the most effective in enhancing oxygen tolerance. When ROI scavengers were combined
with dimethyl sulfoxide, the effects of allopurinol, azelaic acid, caffeine, cimetidine, and pyruvate
were even more pronounced than when they were used alone. A combination of
tetramethylpiperidine-1-oxyl (1EMPOL), a superoxide dis mutase mimic, with pyruvate also
enhanced oxygen tolerance effectively. A survey of the literature dealing with the types of ROIs
destroyed by scavengers used in our study suggests that hydrogen peroxide (H202) and hydroxyl
radicals (OH.) are the most toxic ROIs for Campylobacter species. === Master of Science |
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