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In this study, we explored how ammonium and metal ion stresses affected the production of recombinant hyperthermostable manganese superoxide dismutase (Mn-SOD). To improve Mn-SOD production, fed-batch culture in shake flasks and bioreactor fermentation were undertaken to examine the effects of [Formula: see text] and Mn(2+) feeding. Under the optimized feeding time and concentrations of [Formula: see text] and Mn(2+), the maximal SOD activity obtained from bioreactor fermentation reached some 480 U/ml, over 4 times higher than that in batch cultivation (113 U/ml), indicating a major enhancement of the concentration of Mn-SOD in the scale-up of hyperthermostable Mn-SOD production. In contrast, when the fed-batch culture with appropriate [Formula: see text] and Mn(2+) feeding was carried out in the same 5-L stirred tank bioreactor, a maximal SOD concentration of some 450 U/ml was obtained, again indicating substantial increase in SOD activity as a result of [Formula: see text] and Mn(2+) feeding. The isoelectric point (pI) of the sample was found to be 6.2. It was highly stable at 90 °C and circular dichroism measurements indicated a high α-helical content of 70 % as well, consistent with known SOD properties. This study indicates that [Formula: see text] and Mn(2+) play important roles in Mn-SOD expression. Stress fermentation strategies established in this study are useful for large-scale efficient production of hyperthermostable Mn-SOD and may also be valuable for the scale-up of other extremozymes.

Original publication




Journal article



Publication Date





995 - 1002


Ammonia, Bacterial Proteins, Batch Cell Culture Techniques, Bioreactors, Fermentation, Manganese, Stress, Physiological, Superoxide Dismutase, Thermus thermophilus