硼处理根瘤菌胞外多糖提取条件优化

Optimization of extraction for extracellularpolysaccharides produced by rhizobiumthrough boron treatment

摘要:

为了研究硼处理根瘤菌12531f胞外多糖的提取条件,以根瘤菌12531f为材料,筛选适宜硼浓度并以此浓度处理为诱导条件,优化三氯乙酸体积分数、醇沉倍数和醇沉时间。结果表明:1 mg/L的硼处理菌株12531f可以显著提高胞外多糖的含量;通过L9(34)正交实验发现,在三氯乙酸体积分数10%、醇沉时间24 h的条件下,醇沉倍数由2倍提高到3倍时,硼处理根瘤菌12531f菌株胞外多糖平均含量最高,达33.23 μg/mL,与优化前相比,胞外多糖含量提高了56.97%。得到纯度高、含杂量低的胞外多糖,有利于进行进一步结构鉴定和分析,为硼处理根瘤菌12531f菌株胞外多糖的进一步研究奠定良好基础。

Abstract:

Extracellular polysaccharides secreted by alfalfa rhizobium can,at the time of infection,weaken the defense responses of host plants.This would promote the colonization of rhizobia and endogenously grow in seeds by forming a symbiosis between seeds and rhizobia,leading to the enhanced nodulation and nitrogen fixation of alfalfa seedlings germinated from those seeds.To study the effects of boron treatments on the extraction for extracellular polysaccharides produced by rhizobia 12531f,an appropriate boron concentration was determined.Under the optimum boron concentration,the volume fraction of trichloroacetic acid,time of alcohol precipitation,and volume of alcohol for precipitation.Our results showed that the production of extracellular polysaccharides by strain 12531f was significantly increased under 1 mg L?1 boron.Through the L9(34) orthogonal test,the extracellular polysaccharide excreted by rhizobium 12531f increased by 57% (to a value of 33.23 μg/mL) compared with before optimization,when the volume of alcohol for precipitation was increased from two times to three times,under 10% trichloroacetic acid with an alcohol precipitation time of 24 h.The purification of extracellular polysaccharides provides important foundation for the identification and analysis of its structural in future.