桃色欧文氏菌Cp2胞外多糖测定方法及培养条件的优化

Optimization of the method for determiningexopolysaccharides and culture conditions ofErwinia persicina Cp2

摘要:

【目的】 明确紫花苜蓿（Medicago sativa）种带桃色欧文氏菌（Erwinia persicina）Cp2 胞外多糖（exopolysaccharides，EPS）的含量测定方法及其最佳培养条件，获得更高产量的胞外多糖。【方法】采用单因素试验优化Cp2 EPS 的测定方法和培养条件。【结果】 优化后的苯酚硫酸法测定条件为最大吸收波长490 nm、显色时间20 min、显色温度100 ℃、苯酚质量分数5%、苯酚用量0. 80 mL、浓硫酸用量5. 00 mL；优化后的最适培养基为大豆蛋白胨20. 00 g、K2HPO4 1. 50 g、MgSO4·7H2O 1. 50 g、淀粉25. 00 g、蒸馏水1. 00 L，pH 值 7. 0~7. 2，121 ℃灭菌15 min；富集培养温度30 ℃。【结论】 苯酚硫酸法较蒽酮硫酸法更适于测定Cp2 EPS。采用优化后的培养条件桃色欧文氏菌Cp2 EPS 产量较优化前增加了365. 91%。同时本研究结果将为桃色欧文氏菌Cp2 胞外多糖的功能研究及产品开发提供理论基础。

Abstract:

【Objective】 To determine the content of exopolysaccharides（EPS） in seed-borne Erwinia persicinaCp2 present in alfalfa and identify its optimum culture conditions for achieving higher yield of EPS.【Method】 Asingle-factor test was employed to optimize the determination method and culture conditions of Cp2 EPS.【Result】The optimized conditions for the phenol-sulfuric acid method were determined as follows： maximum absorptionwavelength of 490 nm，color development time of 20 min，color development temperature of 100 ℃，phenol mass frac-tion of 5%，phenol dosage 0. 80 mL，and concentrated sulfuric acid dosage of 5. 00 mL. The optimized medium forCp2 EPS production included soy peptone （20. 00 g），dipotassium hydrogen phosphate （1. 50 g），magnesium sulfate（1. 50 g），starch （25. 00 g），distilled water （1. 00 L）maintained at pH 7. 0~7. 2，sterilization at 121 ℃ for 15 min，and the enrichment culture temperature of 30 ℃ .【Conclusion】 The results revealed that the phenol-sulfuric acidmethod was superior to anthrone-sulfuric acid in determining the Cp2 EPS content，resulting in 365. 91% increasein Cp2 EPS production compared to the previous method. This study provides a theoretical basis for the functional re-search and product development of Erwinia persicina strain Cp2 exopolysaccharides.