Effect of Vitreoscilla hemoglobin on growth characteristics of radioresistant Deinococcus radiodurans

This study investigated the effect of Vitreoscilla hemoglobin, known to supply the heterologoues hosts with better growth and higher oxygen uptake, on growth, oxygen uptake and radioresistancy of Deinococcus radiodurans, a bacterium known for its extraordinary radioresistant properties. The wild-type and two recombinants, one carrying the Vitreoscilla hemoglobin gene (vgb+) and the other missing it (vgb-), were exposed to various doses of ionize radiation and investigated for their survival properties. Furthermore, given its relation of level of oxygen and radiation, the activities of catalase and superoxide dismutase and as well as the level of the reducing agent glutathione were investigated in comparative fashion.Results showed that, both recombinant strains became highly sensitive to radiation and they had considerably higher growth rates than the wild-type strain. Further, both recombinant strains had substantially lower oxygen uptake rate, reduced superoxide dismutase activity and glutathione level compared to the wild-type host strain. The catalase activity in recombinants, in contrast, was higher than that of in the host strain. As an indicator of radioresictancy, the cellular level of Mn/Fe in wild-type host was 3-fold higher than that of in recombinant strains.