碱胁迫对银杏内生菌Lysinibacillus sphaericus Ya6产胞外多糖的影响

Effects of alkali stress on the production of exopolysaccharides by endophyte Lysinibacillus sphaericus Ya6 from Ginkgo biloba L.

逆境下生物会产生多种应激反应和生理特性变化,胁迫下代谢变化的研究对诱导产生新型化合物等具有重要意义。采用邻苯三酚自氧化法、水杨酸法等测定了银杏内生菌Lysinibacillus sphaericus Ya6在不同程度碱胁迫下(pH 8~10)产胞外多糖的抗氧化性变化,分别采用紫外扫描、红外扫描、硫酸钡比浊法测定了其结构变化。结果表明,碱胁迫使Lysinibacillus sphaericus Ya6所产胞外多糖对超氧阴离子、羟自由基的清除能力有所提升;对DPPH自由基清除能力显著提升,pH为10时,胞外多糖的DPPH自由基清除率高达95.65%。紫外光谱分析发现样品在260和280 nm处无紫外吸收,表明样品中不含核酸和蛋白质;红外光谱分析表明各多糖样品均存在典型的多糖特征吸收峰,且存在甘露糖-吡喃糖结构,但吸收峰强度、位置存在差异。

The organisms will produce a variety of stress responses and physiological characteristics changes under stress.The study of metabolic changes under stress has great significance for inducing the production of new compounds.The antioxidation of exopolysaccharide produced by endophyte Lysinibacillus sphaericus Ya6 under alkali stress(pH 8-10)were determined by pyrogallol autoxidation method and salicylic acid method.The structural changes of exopolysaccharide were determined by ultraviolet scanning,infrared scanning and barium sulfate turbidimetry.The results showed that alkali stress forced Lysinibacillus sphaericus Ya6 exopolysaccharide to improve its ability to scavenge superoxide anions and hydroxyl radical.The scavenging capacity of DPPH free radical was significantly improved.The DPPH free radical scavenging rate of extracellular polysaccharide could reach to 95.65%when pH was 10.UV spectrum analysis showed that there were no absorption at 260 or 280 nm,indicating that the sample did not contain nucleic acid or protein.The infrared spectrum analysis showed that there were typical polysaccharide characteristic absorption peaks and mannose pyranose structure in each polysaccharide sample,but the intensity and location of absorption peaks were different.