pH对桑黄TH021菌株液体发酵抗氧化能力的影响

Effect of pH on antioxidant ability of Phellinus igniarius TH021 strain in liquid fermentation

【目的】探索pH对桑黄TH021菌株液体发酵及其甲醇提取物抗氧化能力和主要活性成分的影响,为充分利用该菌提供依据。【方法】用5L机械搅拌发酵罐在pH 4.5,5.5,6.5和7.5下进行桑黄TH021菌株液体发酵,于培养第8天时获取滤液、菌丝体,测定其生长速率,分析甲醇提取物对DPPH自由基清除能力、亚铁离子螯合作用、超氧阴离子清除作用及主要活性成分含量,研究pH对桑黄TH021液体发酵甲醇提取物抗氧化能力及活性成分的影响。【结果】桑黄TH021菌株生长的最适pH值为6.5。在pH为6.5时,桑黄TH021菌株滤液甲醇提取物产量(LYC)达到最高,为(4.63±0.01)g/L;桑黄TH021菌株液体发酵菌丝体甲醇提取物对DPPH、超氧阴离子的清除作用,以及滤液甲醇提取物对亚铁离子的螯合作用均达到最高;菌丝体甲醇提取物总酚含量和黄酮类物质含量均达到最高,分别为(14.04±1.69)和(9.21±1.14)mg/g。在pH为7.5时,桑黄TH021菌株液体发酵滤液甲醇提取物多糖含量达到最高,为(66.10±1.96)mg/g。【结论】pH对桑黄TH021菌株液体发酵甲醇提取物抗氧化能力及主要活性成分有显著影响,因此要在适宜的pH下使用。

【Objective】This study explored the influence of culturing pH on liquid fermentation of Phellinus igniarius TH021 strain,the antioxidant capacity of its methanol extracts,and the main bioactive compounds to provide theoretical basis for making full use of the strain.【Method】Liquid fermentation of Phellinus igniarius TH021 strain at controlled pH of 4.5,5.5,6.5,and 7.5was conducted in a 5Lstirring fermenter.After 8days,the growth rate,DPPH radical scavenging activities,and scavenging effects of ferrous ions were determined.The influence of pH on antioxidant capacity of methanol extract and active ingredients of Phellinus igniarius TH021 strain in liquid fermentation were analyzed.【Result】The optimal pH value for mycelium growth of Phellinus igniarius TH021 strain was 6.5.At pH 6.5,the yield of filtrate methanol extract of Phellinus igniarius TH021 strain reached the highest value of（4.63±0.01）g/L.The DPPH radical scavenging capacity and scavenging ability of superoxide anion of the methanol extracts of mycelia,and ferrous ion chelation of the methanol extracts also reached the highest level at pH 6.5.Antioxidant production reached maximum at pH 7.5and the polysaccharide content in extracts was（66.10±1.96）mg/g.The maximum total phenolic content and flavonoids content of the methanol ex-tracts of mycelia were（14.04±1.69）mg/g and（9.21±1.14）mg/g at pH 6.5,respectively.【Conclusion】pH significantly affected antioxidant ability and contents of antioxidant compounds of methanol extracts of liquid fermentation of TH021 strain.