香菇多糖发酵工艺优化、结构表征与抗氧化功能研究

Research on the optimization of fermentation process, structural characterization and antioxidant activity of Lentinula edodes polysaccharides

中文关键词:  香菇  胞外多糖  单因素试验  响应面  结构表征  抗氧化

英文关键词:Lentinula edodes  exopolysaccharides  single-variable experiment  response surface analysis  structural characterization  antioxidant properties

中文摘要:

      目的 研究香菇液体发酵高产胞外多糖的最适培养基组成及发酵工艺, 并对所得胞外多糖进行结构表征和抗氧化活性评价。方法 通过单因素试验筛选最适碳源、氮源及其浓度, 同时筛选在发酵条件(pH、装液量、转速、接种量、发酵天数)中对香菇胞外多糖产量影响显著的3因素(pH、装液量、转速)进行响应面优化。采用扫描电镜、紫外光谱、红外光谱及热重分析对最优条件下制备的胞外多糖进行结构表征, 并测定其对1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-trinitrophenylhydrazine, DPPH)自由基、2,2-联氮-二(3-乙基-苯并噻唑啉-6-磺酸)二铵盐[2,2-biazo-di (3-ethyl-benzothiazolin-6-sulfonic acid) diammonium salt, ABTS]阳离子自由基及羟基自由基的清除能力。结果 香菇液体发酵最适碳氮源及浓度为葡萄糖20 g/L、酵母膏5 g/L; 最佳发酵工艺为pH 6、装液量101 mL、转速149 r/min、接种量5%、发酵天数8 d。扫描电子显微镜显示在此条件下所得胞外多糖结构疏松; 紫外光谱显示无核酸和蛋白质特征吸收, 红外光谱在3408.1、2920.5、1646.1、1324.5 cm–1等处呈现多糖特征吸收峰, 热重分析表明在28~180 ℃香菇多糖热稳定性较好, 胞外多糖对DPPH自由基、ABTS阳离子自由基及羟自由基均有较好的清除率, 分别为60.14%、53.47%、93.94%。结论 本研究优化香菇菌种液体发酵产胞外多糖的工艺, 确定该工艺稳定可行, 为提升发酵效率、增加香菇多糖产量及其进一步开发利用提供理论依据。

英文摘要:

      Objective To determine the best medium composition and fermentation conditions to maximize the production of exopolysaccharides from Lentinula edodes through submerged fermentation, as well as to analyze the structure and assess the antioxidant properties of the extracted exopolysaccharides. Methods Single-factor experiments were conducted to identify the optimal carbon and nitrogen sources and their concentrations. Furthermore, 3 key factors influencing the yield of Lentinula edodes exopolysaccharides—pH, liquid volume and agitation speed were selected for response surface methodology optimization under controlled fermentation parameters (pH, liquid volume, rotation speed, inoculum size and fermentation time). The exopolysaccharides produced under these optimized conditions were characterized using scanning electron microscopy, ultraviolet spectroscopy, infrared spectroscopy and thermogravimetric analysis. Their ability to scavenge free radicals, including 1,1-diphenyl-2-trinitrophenylhydrazine (DPPH), 2,2-biazo-di (3-ethyl-benzothiazolin-6-sulfonic acid) diammonium salt, and hydroxyl radicals, was also evaluated. Results Glucose at 20 g/L and yeast extract at 5 g/L were identified as the optimal carbon and nitrogen sources, respectively, for submerged fermentation of Lentinula edodes. The ideal fermentation parameters were pH 6, liquid volume of 101 mL, agitation speed of 149 r/min, inoculum size of 5% and an 8-day fermentation period. Scanning electron microscope images showed that the exopolysaccharides had a loose structural morphology. Ultraviolet spectroscopy revealed no absorption peaks indicative of nucleic acids or proteins, while infrared spectroscopy displayed characteristic polysaccharide absorption bands at 3408.1, 2920.5, 1646.1 and 1324.5 cm–1. Thermogravimetric analysis demonstrated that the polysaccharides maintained good thermal stability between 28 ℃ and 180 ℃. The exopolysaccharides exhibited strong antioxidant activity, with scavenging rates of 60.14% for DPPH radicals, 53.47% for ABTS cationic radicals and 93.94% for hydroxyl radicals. Conclusion The study optimize the submerged fermentation process for producing exopolysaccharides from Lentinula edodes, confirming the method’s stability and practicality. These findings provide a theoretical foundation for enhancing fermentation efficiency, increasing polysaccharide yields and supporting further development and application of Lentinula edodes polysaccharides.