(751a) High Cell Density Fermentation of Deinococcus Radiodurans Under Optimized Conditions

Deinococcus radiodurans (DR) is the #1 candidate for bioremediating nuclear waste site, due to its unique ability to resist high doses of radiation. Its radiation resistance mechanism has been under intense investigation. However, studies of its growth media and growth conditions are scarce, and its large scale production has not been reported. In this study, a systematic investigation was carried out to produce DR at the 20-L fermentor scale. The phosphate buffer typically used was found to be inhibitory to DR growth, and caused cell grouping. HEPES and MOPS buffer helped DR growth. Several antifoams were investigated to support large scale production with submerged aeration, and KFO 673 defoamer was chosen based on its ability to prevent foaming without affecting DR growth. The traditional TGY media only support DR growth to 10 OD600. Using a Design of Experiments approach, glucose, Mg, Mn were found to be critical to support high density growth of DR. With addition of 10 g/L glucose, 0.5 g/L MgSO4?7H2O, 5 µM MnCl2 into TGY media, OD600 of 40 was achieved. The optimal pH and temperature for DR growth were found to be 7.0 and 37 oC, respectively. Fermentation was carried out in a 20-L fermentor using the newly developed media under the optimal conditions.