title: Stress fermentation strategies for the production of hyperthermostable superoxide dismutase from Thermus thermophilus HB27: effects of ions.
abstract: 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.
authors.affiliation: State Key Laboratory of Heavy Oil Processing and Centre for Bioengineering and Biotechnology, China University of Petroleum (East China), 66 Changjiang West Road, Qingdao, 266580, People's Republic of China.
authors.forename: Hu
authors.initials: H
authors.lastname: Zhu
authors.forename: Jianguo
authors.initials: J
authors.lastname: Liu
authors.forename: Jianbo
authors.initials: J
authors.lastname: Qu
authors.forename: Xinliang
authors.initials: X
authors.lastname: Gao
authors.forename: Tao
authors.initials: T
authors.lastname: Pan
authors.forename: Zhanfeng
authors.initials: Z
authors.lastname: Cui
authors.forename: Xiubo
authors.initials: X
authors.lastname: Zhao
authors.forename: Jian R
authors.initials: JR
authors.lastname: Lu
mesh_terms: D000641:Ammonia / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D061249:Batch Cell Culture Techniques / Q000295:instrumentation / Q000379:methods; D019149:Bioreactors; D005285:Fermentation; D008345:Manganese / Q000494:pharmacology*; D013312:Stress, Physiological; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism*; D016963:Thermus thermophilus / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D008345:Manganese; D000641:Ammonia; D013482:Superoxide Dismutase
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