落叶松锈迷孔菌产多糖液体培养基的优化及其体外抗氧化活性

本研究通过响应面设计优化了落叶松锈迷孔菌产胞外多糖的液体培养基,并对其体外抗氧化活性进行了分析。结果显示,以落叶松锈迷孔菌胞外多糖产量为响应值,采用Plackett-Burman设计、最陡爬坡设计和Box-Behnken设计建立数学模型,获得落叶松锈迷孔菌产胞外多糖的最适培养基为：去皮马铃薯415.70g/L、蛋白胨10.80g/L、葡萄糖20.0g/L、吐温80 7.27mL/L、KH₂PO₄ 1.0g/L、MgSO₄?7H₂O 0.5g/L、CaCO₃ 0.57g/L、FeSO₄?7H₂O 0.3g/L、ZnSO₄?7H₂O 0.3g/L、维生素B₁ 0.01g/L、芦丁6.09g/L。在此优化条件下得到的多糖产量为3.07g/L,与理论值3.06g/L相近,相比于优化前提高了2.87倍,说明响应面法对于优化落叶松锈迷孔菌的液体培养基以提高多糖产量行之有效。此外,经过醇沉、透析和去蛋白等获得初步纯化的多糖可有效清除羟自由基、超氧阴离子、1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基和2,2?-连氮-双(3-乙基苯并噻唑-6-磺酸)2,2?-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid),ABTS]自由基。

Medium optimization and in vitro antioxidant activities of exopolysaccharides of Porodaedalea laricis

Liquid medium of Porodaedalea laricis was optimized by response surface methodology for increasing exopolysaccharide yield, and in vitro antioxidant activities of the preliminarily purified exopolysaccharide were evaluated. Plackett-Burman design, the steepest ascent path and Box-Behnken design were employed to establish mathematical model using exopolysaccharide yield as response value. The optimal medium for high production of P. laricis exopolysaccharide was composed of peeled potato 415.70g/L, peptone 10.80g/L, glucose 20.0g/L, Tween 80 7.27mL/L, KH₂PO₄ 1.0g/L, MgSO₄?7H₂O 0.5g/L, CaCO₃ 0.57g/L, FeSO₄?7H₂O 0.3g/L, ZnSO₄?7H₂O 0.3g/L, vitamin B₁ 0.01g/L and rutin 6.09g/L. By use of the optimized medium, the exopolysaccharide yield was 3.07g/L, being closely consistent with the theoretical value of 3.06g/L predicted by the developed model, and this yield was 2.87-fold higher than that obtained in unoptimized medium. The result indicated that the response surface methodology is available for optimizing the medium composition with the purpose of increasing exopolysaccharide yield of P. laricis. The exopolysaccharide preliminarily purified by ethanol precipitation, dialysis and deproteination exhibited effective scavenging activities against hydroxyl, superoxide, DPPH and ABTS radicals.