He Zhongqi, Griffin Timothy S, Honeycutt C Wayne
USDA Agricultural Research Service, New England Plant, Soil, and Water Laboratory, University of Maine, Orono, ME 04469, USA.
J Environ Qual. 2004 Jan-Feb;33(1):367-72.
Organic phosphorus (Po) exists in many chemical forms that differ in their susceptibility to hydrolysis and, therefore, bioavailability to plants and microorganisms. Identification and quantification of these forms may significantly contribute to effective agricultural P management. Phosphatases catalyze reactions that release orthophosphate (Pi) from Po compounds. Alkaline phosphatase in tris-HCl buffer (pH 9.0), wheat (Triticum aestivum L.) phytase in potassium acetate buffer (pH 5.0), and nuclease P1 in potassium acetate buffer (pH 5.0) can be used to classify and quantify Po in animal manure. Background error associated with different pH and buffer systems is observed. In this study, we improved the enzymatic hydrolysis approach and tested its applicability for investigating Po in soils, recognizing that soil and manure differ in numerous physicochemical properties. We applied (i) acid phosphatase from potato (Solanum tuberosum L.), (ii) acid phosphatases from both potato and wheat germ, and (iii) both enzymes plus nuclease P1 to identify and quantify simple labile monoester P, phytate (myo-inositol hexakis phosphate)-like P, and DNA-like P, respectively, in a single pH/buffer system (100 mM sodium acetate, pH 5.0). This hydrolysis procedure released Po in sequentially extracted H2O, NaHCO3, and NaOH fractions of swine (Sus scrofa) manure, and of three sandy loam soils. Further refinement of the approach may provide a universal tool for evaluating hydrolyzable Po from a wide range of sources.
有机磷（Po）以多种化学形式存在，它们对水解的敏感性不同，因此对植物和微生物的生物有效性也不同。这些形式的鉴定和定量可能对有效的农业磷管理有显著贡献。磷酸酶催化从Po化合物中释放正磷酸盐（Pi）的反应。三羟甲基氨基甲烷盐酸盐缓冲液（pH 9.0）中的碱性磷酸酶、醋酸钾缓冲液（pH 5.0）中的小麦（Triticum aestivum L.）植酸酶以及醋酸钾缓冲液（pH 5.0）中的核酸酶P1可用于对动物粪便中的Po进行分类和定量。观察到与不同pH和缓冲系统相关的背景误差。在本研究中，我们改进了酶促水解方法，并测试了其在研究土壤中Po方面的适用性，因为我们认识到土壤和粪便在许多物理化学性质上存在差异。我们应用（i）马铃薯（Solanum tuberosum L.）酸性磷酸酶、（ii）马铃薯和小麦胚芽的酸性磷酸酶以及（iii）这两种酶加核酸酶P1，分别在单一pH/缓冲系统（100 mM醋酸钠，pH 5.0）中鉴定和定量简单的不稳定单酯磷、植酸盐（肌醇六磷酸）样磷和DNA样磷。这种水解程序从猪（Sus scrofa）粪便以及三种砂壤土的依次提取的水、碳酸氢钠和氢氧化钠组分中释放出Po。该方法的进一步完善可能为评估来自广泛来源的可水解Po提供一种通用工具。
