Production, extraction and characterization of Chlorella vulgaris soluble polysaccharides and their applications in AgNPs biosynthesis and biostimulation of plant growth
Production, extraction and characterization of Chlorella vulgaris soluble polysaccharides and their applications in AgNPs biosynthesis and biostimulation of plant growth
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DOI：
10.1038/s41598-020-59945-w
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发表时间：
2020-02-20
影响因子：
4.6
通讯作者：
Dalal, Shimaa R.
中科院分区：
文献类型：
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作者：
El-Naggar, Noura El-Ahmady;Hussein, Mervat H.;Dalal, Shimaa R.
与其他多种微藻一样，小球藻能够混合营养生长。这最大限度地提高了其生长和多糖 (PS) 的产量。提取的多糖具有复杂的单糖成分（果糖、麦芽糖、乳糖和葡萄糖）、硫酸盐（210.65 +/- 10.5 mg g(-1) PS）、糖醛酸（171.97 +/- 5.7 mg g(-1) PS）、总蛋白质含量（32.99 +/- 2.1 mg g(-1) PS）和总碳水化合物 （495.44 +/- 8.4 毫克克(-1) PS）。提取的多糖的傅里叶变换红外光谱 (FT-IR) 分析表明存在 N-H、O-H、C-H、-CH3、>CH2、COO-1、S=O 和 C=O 官能团。紫外-可见光谱分析显示蛋白质、核酸和化学基团（酯、羰基、羧基和胺）的存在。纯化的多糖呈浅绿色，无味粉末形式。溶于水，不溶于其他有机溶剂。热重分析表明，小球藻可溶性多糖在 240 摄氏度之前都是热稳定的，并且降解发生在三个不同的阶段。差示扫描量热法 (DSC) 分析显示，小球藻可溶性多糖具有特征性放热转变，结晶温度峰值分别为 144.1 ℃、162.3 ℃ 和 227.7 ℃。X 射线衍射图说明了这些多糖的半结晶性质。使用普通小球藻可溶性多糖溶液生物合成银纳米粒子（AgNP）。可溶性多糖的浅绿色溶液与100 mM硝酸银在黑暗中孵育24小时后变成棕色，在430 nm处显示最大峰。生物合成的 AgNP 的 FT-IR 分析表明存在羰基、-CH3、>CH2、C-H、-OH 和 -NH 官能团。扫描和透射电镜显示AgNPs呈球形，平均粒径为5.76。能量色散 X 射线 (EDX) 分析显示银占主导地位。生物合成的银纳米粒子经过测试其抗菌活性，对芽孢杆菌、欧文氏菌、念珠菌具有积极作用。用多糖溶液（3 和 5 mg mL(-1)）对小麦和菜豆种子进行引发处理，可显着促进幼苗生长。观察到根长、叶面积、芽长、光合色素、蛋白质含量、碳水化合物含量、新鲜和干生物量的增加，此外这些生长增量可能归因于抗氧化活性的增加。
Chlorella vulgaris, like a wide range of other microalgae, are able to grow mixotrophically. This maximizes its growth and production of polysaccharides (PS). The extracted polysaccharides have a complex monosaccharide composition (fructose, maltose, lactose and glucose), sulphate (210.65 +/- 10.5 mg g(-1) PS), uronic acids (171.97 +/- 5.7 mg g(-1) PS), total protein content (32.99 +/- 2.1 mg g(-1) PS), and total carbohydrate (495.44 +/- 8.4 mg g(-1) PS). Fourier Transform infrared spectroscopy (FT-IR) analysis of the extracted polysaccharides showed the presence of N-H, O-H, C-H, -CH3, >CH2, COO-1, S=O and the C=O functional groups. UV-Visible spectral analysis shows the presence of proteins, nucleic acids and chemical groups (ester, carbonyl, carboxyl and amine). Purified polysaccharides were light green in color and in a form of odorless powder. It was soluble in water but insoluble in other organic solvents. Thermogravimetric analysis demonstrates that Chlorella vulgaris soluble polysaccharide is thermostable until 240 degrees C and degradation occurs in three distinct phases. Differential scanning calorimetry (DSC) analysis showed the characteristic exothermic transition of Chlorella vulgaris soluble polysaccharides with crystallization temperature peaks at 144.1 degrees C, 162.3 degrees C and 227.7 degrees C. The X-ray diffractogram illustrated the semicrystalline nature of these polysaccharides. Silver nanoparticles (AgNPs) had been biosynthesized using a solution of Chlorella vulgaris soluble polysaccharides. The pale green color solution of soluble polysaccharides was turned brown when it was incubated for 24 hours with 100 mM silver nitrate in the dark, it showed peak maximum located at 430 nm. FT-IR analysis for the biosynthesized AgNPs reported the presence of carbonyl, -CH3, >CH2, C-H,-OH and -NH functional groups. Scanning and transmission electron microscopy show that AgNPs have spherical shape with an average particle size of 5.76. Energy-dispersive X-ray (EDX) analysis showed the dominance of silver. The biosynthesized silver nanoparticles were tested for its antimicrobial activity and have positive effects against Bacillus sp., Erwinia sp., Candida sp. Priming seeds of Triticum vulgare and Phaseolus vulgaris with polysaccharides solutions (3 and 5 mg mL(-1)) resulted in significant enhancement of seedling growth. Increased root length, leaf area, shoot length, photosynthetic pigments, protein content, carbohydrate content, fresh and dry biomass were observed, in addition these growth increments may be attributed to the increase of antioxidant activities.