Enzymatic Hydrolysis of Organic Phosphorus in Swine Manure and Soil

Abstract

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.

Effect of Drying on Phosphorus Distribution in Poultry Manure

“…A modified Hedley sequential fractionation procedure as described by He, Griffin, and Honeycutt (2004a) was used in this study. Each sample (0.25 g, 658C dry equivalent) was sequentially extracted in 25 mL of distilled water, 0.5 M NaHCO 3 (pH 8.5), 0.1 M NaOH, and 1 M HCl for 2 h (water) or 16 h (all others) at 228C on an orbital shaker at 250 rpm.…”

A Modified Molybdenum Blue Method for Orthophosphate Determination Suitable for Investigating Enzymatic Hydrolysis of Organic Phosphates

“…For incubation experiments, the extract was diluted to one-half, one-fourth, or one-eighth fold and adjusted to pH 5.0 in 100 mM sodium acetate buffer. Combinations of acid phosphatases from potato and wheat germ and nuclease P1 were used to release hydrolysable P o in the diluted extracts as detailed by He et al (2004). The reaction mixtures were incubated at 378C; and 50, 100, or 200 mL were taken off at various time intervals for P i determination.…”

Phosphatase Hydrolysis of Organic Phosphorus Compounds

“…The dephosphorylation of OP compounds in soils largely depends on the stereochemical and stereoisomeric structures of the OP compounds in question, in addition to the type and enzyme sources involved in such catalytic hydrolysis. The high affinity of some enzymes for particular substrates has been used as the basis to identify and quantify specific OP compounds, or as part of post separation quantification step [20]- [23]. Strickland and Solorzano [24] used alkaline phosphatase to assess bioavailable P hydrolyzed by exocellular algal phosphatase released due to phosphate depletion.…”