Department of Environmental Studies, University of Delhi, Delhi, 110007, India.
Aquagreen Engineering Management Pvt. Ltd., Ansal Chambers, Bhikaji Cama Place, New Delhi, 110066, India.
Protoplasma. 2020 Jan;257(1):319-330. doi: 10.1007/s00709-019-01424-9. Epub 2019 Jul 29.
Owing to its essentiality for cellular metabolism, phosphate (PO) plays a pivotal role in ecosystem dynamics. Frequent testing of phosphate levels is necessary to monitor ecosystem health. Present investigations were aimed to identify the key factors that are essential for proper quantification of PO. Primarily, H levels played a critical role in the development of molybdenum blue complex by ammonium molybdate and PO with ascorbic acid as a reductant. Molybdenum blue complex formed in the presence of 8 to 12 mmol of H in 3 ml reaction mixture remained stable even after 72 h. Of different concentrations of ammonium molybdate and ascorbic acid tested, best molybdenum blue complex was formed when their concentrations were 24.3 and 5.68 μmol, respectively. More or less similar intensity of molybdenum blue complex (due to reduction of phosphomolybdic acid and not molybdic acid) was formed in the presence of H at levels ranging from 8 to 10 mmol in 3 ml reaction mixture. Our findings unequivocally demonstrated that (i) the reaction mixture containing 3% ammonium molybdate, 0.1% ascorbic acid and 5 M HSO in the ratio of 1:1:1 is ideal for PO quantification; (ii) antimony (Sb) significantly curbs the formation of molybdenum blue under these ideal conditions; (iii) this fine-tuned protocol for PO quantification could be extended without any problem for determining the level of PO both in plant as well as soil samples; and (iv) Azotobacter possesses potential to enhance levels of total PO in leaves and grains and soluble/active PO in rhizosphere soils of wheat.
由于磷酸盐（PO）对细胞代谢至关重要，因此在生态系统动态中起着关键作用。为了监测生态系统健康，需要频繁测试磷酸盐水平。目前的研究旨在确定对 PO 进行正确定量所需的关键因素。首先，H 水平在钼蓝络合物的形成中起着关键作用，该络合物由钼酸铵和 PO 与抗坏血酸作为还原剂形成。在 3ml 反应混合物中存在 8 至 12mmol 的 H 时形成的钼蓝络合物即使在 72 小时后仍保持稳定。在所测试的不同浓度的钼酸铵和抗坏血酸中，当它们的浓度分别为 24.3 和 5.68μmol 时，形成了最佳的钼蓝络合物。在 3ml 反应混合物中存在 8 至 10mmol 的 H 时，形成了类似强度的钼蓝络合物（由于磷酸钼酸的还原而不是钼酸的还原）。我们的研究结果明确表明：（i）在 3%钼酸铵、0.1%抗坏血酸和 5M HSO 的比例为 1:1:1 的反应混合物中，（ii）锑（Sb）在这些理想条件下显著抑制钼蓝的形成；（iii）在不影响植物和土壤样品中 PO 水平的情况下，可以毫无问题地扩展这种用于 PO 定量的精细调整方案；（iv）固氮菌具有提高叶片和谷物中总 PO 以及根际土壤中可溶性/活性 PO 水平的潜力。
