Evaluation of the mineralizable organic nitrogen in soil using an immunological technique

摘要

Phosphate buffer-extractable organic nitrogen (PEON), which can be extracted from soil with a 67-mM neutral phosphate buffer solution, is considered to be a major source of mineralizable nitrogen (N) that is ubiquitous in soil. We have developed a Western blot analysis and enzyme-linked immune sorbent assay (ELISA) method for determining PEON. First, anti-PEON antibody (IgG) from a rabbit was produced using purified PEON from a volcanic ash soil. PEON was detected as a ladder-like staining pattern in the high-molecular-weight region and as a single band under 14 kDa in Western blot analysis using the anti-PEON IgG. In the ELISA assay, the anti-PEON IgG could specifically react with PEON irrespective of soil type and management. Furthermore, the absorbance at 450 nm in ELISA was highly correlated to the concentration of organic N (N-org) in phosphate extracts of different soils. We propose the immune assay using the anti-PEON IgG as a possible novel method for evaluating available N in soil.