两种海藻内生菌的分离及其抗氧化活性研究

Isolation and Antioxidative Activities of Algal Endophytes

为研究不同海藻不同内生菌(细菌、真菌)的抗氧化活性差异,并筛选出抗氧化活性较好的菌株。选取广西北部湾海域绿藻门石莼(Ulva lactuca L.)与褐藻门裙带菜(Undaria pinnatifida Suringar)为研究对象,以其清除DPPH、羟基自由基与超氧阴离子的能力综合评价体外抗氧化活性,在抗氧化能力都较强的前12株菌株中进一步遴选出石莼与裙带菜内生细菌与内生真菌各3株进行深入检测。石莼与裙带菜的内生细菌、真菌对DPPH、羟基自由基与超氧阴离子的清除活性均随质量浓度增加而升高;不同藻类的石莼与裙带菜的内生菌抗氧化活性之间存在显著差异(P<0.05);同种藻类内生菌间,除裙带菜内生真菌外,整体表现为,石莼与裙带菜的内生细菌对DPPH、羟基自由基与超氧阴离子的半抑制浓度IC50值均显著高于内生真菌,说明石莼与裙带菜内生细菌的抗氧化活性显著低于内生真菌。其中,石莼内生真菌SZ-5菌株清除DPPH、羟基自由基与超氧阴离子的综合能力相对最强,IC50依次为(0.59±0.06)、(1.30±0.36)、(1.14±0.35)mg/mL;经分子鉴定为短梗霉菌属真菌Aureobasidium spp.。

The study compared the antioxidative activities of typical algal endophytes in Ulva lactuca L.and Undaria pinnatifida Suringar from Beibu Gulf in Guangxi and screened out the better ones.Among the first 12 strains with stronger antioxidative activities,9 potent strains were screened out for the further study.Results indicated that the scavenging activities of algal endophytes on DPPH,hydroxyl radical and superoxide anions increased with concentrations.There was a significant difference in the antioxidative activity between Ulva lactuca L.and Undaria pinnatifida Suringar(P<0.05).The semi-inhibition concentrations(IC50)of endophytic bacteria from Ulva lactuca L.and Undaria pinnatifida Suringar for DPPH,hydroxyl radical and superoxide anions were significantly higher than those of endophytic fungi,indicating that the antioxidative activities of endophytic bacteria were significantly lower than those of endophytic fungi.SZ-5 strain from Ulva lactuca L.had the strongest potency to scavenge DPPH,hydroxyl and superoxide anions,and the IC50 was(0.59±0.06),(1.30±0.36)mg/mL and(1.14±0.35)mg/mL,respectively.SZ-5 was identified as Aureobasidium spp.