分离自茯砖茶的真菌菌株MJAU EC021的鉴定及培养过程中生理特性

Identification and physiological characteristics in cultivation of fungal strain MJAU EC021 isolated from brick tea

摘要:

【目的】从茯砖茶样中分离纯化得到生长优势菌株，研究其液体培养时的生理生化特性，为茯砖茶实际生产提供依据。【方法】用PDA平板稀释涂布法从茯砖茶中分离纯化菌株。采用常规真菌发酵培养方法，单因素筛选其培养条件，再利用响应面法优化最优培养条件，测定冠突散囊菌发酵液中还原糖、多酚、胞外酶酶活及抗氧化的能力。【结果】利用形态学与ITS序列分析鉴定优势菌株MJAU EC021为冠突散囊菌Eurotium cristatum；最优的培养条件：转速187 r/min，培养时间10 d，培养温度28 °C，冠突散囊菌生物量为21.52 g/L。冠突散囊菌发酵培养过程中4种胞外酶活性均在第10天时达到最大值，第9天时胞外多酚含量达到峰值为0.588 g GAE (没食子酸)/mL；发酵液对1,1-二苯基-2-苦基肼(DPPH)、羟基自由基的清除率达到最大值分别是90%、94%。【结论】真菌菌株MJAU EC021是株冠突散囊菌E. cristatum, 发酵液具有较好的抗氧化能力，是潜在的抗氧化添加剂。

Abstract:

[Objective] The preponderant strain was isolated from brick tea. Studies on its physiological and biochemical characteristics in cultivation, which provide the basis for the actual production of brick tea fermentation. [Methods] Strains were obtained from brick tea by dilution plate method in PDA. Based on common fungus fermentation method, the culture conditions was selected by the single factor method, and than culturing conditions were optimized using response surface methodology. Contents of reducing sugar, polyphenols, enzyme activity and antioxidant capacity from fermented liquid were determined. [Results] The preponderant strain was identified as Eurotium cristatum by the morphology and ITS sequence analysis. The optimization culturing conditions were: 187 r/min, 10 d, 28 °C. And then yield of biomass was 21.52 g/L. The four kinds of extracellular enzyme activity reached the maximum value at 10th days, meanwhile extracellular polyphenol (EP) 0.588 g GAE (gallic acid)/mL at 9th day. The fermentation liquid of E. cristatum showed antioxidant activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radical. The scavenging effects towards DPPH and hydroxyl radical were 90% and 94%, respectively. [Conclusion] Fungal strain MJAU EC021 was E. cristatum. And then the fermentation liquid had good antioxidant capacity, which is a potential antioxidant additive.