采用纳米磨法、酶法辅助超声波法、超声波法和研磨法提取类球红细菌超氧化物歧化酶（SOD），测定SOD活力；以还原力、ABTS+?、?OH和O2-?的清除作用为指标考察这4种提取方法对湿菌体SOD体外抗氧化活性的影响，并比较了纳米磨法和超声波法对干菌体SOD清除?OH和O2-?的作用。结果表明，纳米磨法提取湿菌体和干菌体SOD的活力最高，分别为36.90±1.25 U/g和214.20±7.72 U/g。这4种提取方法提取湿菌体的SOD均具有体外抗氧化活性；纳米磨法SOD的抗氧化活性最好，固液比1:15时，其对ABTS+?、?OH和O2-?的清除率分别为92.1±3.32%、76.90±2.67%和36.90±1.22%，还原力为11.30±0.35。纳米磨法干菌的SOD抗氧化活性优于超声波法，固液比1:20时，其对?OH和 O2-?的清除率分别为57.10±1.96%和79.40±2.71%。类球红细菌SOD具有较强的抗氧化能力，且与菌体浓度呈量效关系，纳米磨法是较优的提取方法。

Superoxide dismutase (SOD) activity levels were determined for the samples extracted from the biomass of Rhodobacter sphaeroides by grinding, ultrasonic extraction, enzyme assisted ultrasonicextraction, and nanomilling. The in vitro antioxidant activity of SODs extracted by the four methods from R. sphaeroides 3757 wet biomass were evaluated via evaluating their reducing power and scavenging capacity against ABTS+?, ?OH, and O2-?. The in vitro antioxidant activity of SODs extracted by ultrasonic approach and nanomilling from R. sphaeroides 3757 dry biomass were compared based on scavenging capacity against ?OH and O2-?. SODs extracted from wet and dry biomass of R. sphaeroides 3757 by nanomilling exhibited activities of 36.90 ± 1.25 U/g and 214.20 ± 7.72 U/g, respectively, which were higher than those of any other extraction method. The SOD antioxidant activity observed for nanomilling from wet biomass of R. sphaeroides 3757 was higher than that of grinding, ultrasonic extraction, and enzyme assisted ultrasonic extraction . For nanomilling, the reducing power was 11.3 ± 0.35 and the scavenging capacities against ABTS+?, ?OH, and O2-? were 92.1 ±3.32%, 76.90 ± 2.67%, and 36.90 ± 1.22%, respectively, when the solid/liquid ratio was 1:15. The antioxidant activity of SOD extracted by nanomilling from dry biomass of R. sphaeroides 3757 was higher than the counterpart extracted by the ultrasonic method. For nanomilling, when solid/liquid ratio was 1:20, the scavenging capacities against ?OH and O2-? were 57.10 ± 1.96% and 79.40 ± 2.71, respectively. The SODs extracted by different methods from both wet and dry biomass of R. sphaeroides 3757 exhibited significant antioxidant activity in vitro in a concentration-dependent manner. These results showed that SODs from R. sphaeroides 3757 exhibit potent in vitro antioxidant activity, and that nanomilling is the optimal extraction method.

国家科技部“十二五” 国家科技支撑计划项目(2012BAK17B11)，北京市教育委员会科技计划面上项目(KM201311417007)；北京市教育委员会科技成果转化和产业化项目(PXM2013_014209_07-000082)；