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- Title
Oxygen uptake rates in the hyperthermophilic anaerobe Thermotoga maritima grown in a bioreactor under controlled oxygen exposure: clues to its defence strategy against oxidative stress.
- Authors
Lakhal, Raja; Auria, Richard; Davidson, Sylvain; Ollivier, Bernard; Durand, Marie-Claire; Dolla, Alain; Hamdi, Moktar; Combet-Blanc, Yannick
- Abstract
2.3-L bioreactor was specially adapted to grow hyperthermophilic microorganisms under controlled conditions of temperature, pH, redox potential and dissolved O. Using this bioreactor regulated at 80°C and pH 7.0, we demonstrated that Thermotoga maritima recovered its growth despite being exposed to oxygen for a short time (30 min with a maximum concentration of 23 μM of dissolved oxygen). Under these conditions, we demonstrated that O uptake rate, estimated at 73.6 μmoles O min g proteins for dissolved oxygen, was optimal and constant, when dissolved oxygen was present in a range of 22-5 μM. Transcription analyses revealed that during short oxygen exposure, T. maritima expressed genes coding for enzymes to deal with O and reactive oxygen species (ROS) such as peroxides. Thus, genes encoding ROS-scavenging systems, alkyl hydroperoxide reductase ( ahp), thioredoxin-dependent thiol peroxidase ( bcp 2) and to a lesser extent neelaredoxin ( nlr) and rubrerythrin ( rbr), were found to be upregulated during oxygen exposure. The oxygen reductase FprA, homologous to the rubredoxin-oxygen oxidoreductase (ROO) found in Desulfovibrio species, is proposed as a primary consumer of O in T. maritima. Moreover, the expression of frpA was shown to depend on the redox (Eh) level of the culture medium.
- Subjects
THERMOPHILIC bacteria; ANAEROBIC bacteria growth; OXYGEN; BIOREACTORS; OXIDATIVE stress
- Publication
Archives of Microbiology, 2011, Vol 193, Issue 6, p429
- ISSN
0302-8933
- Publication type
Article
- DOI
10.1007/s00203-011-0687-8