ATP in soil: A new extractant and extraction procedure

An extraction mixture comprised of 0.67 m H₃PO₄, 2 m urea, 20% DMSO, 1.8 mg of adenosine, 20 mM EDTA, and 1% Zwittergent 3,10 and a procedure to extract ATP from soil have been developed. The reagents and method were tested on six different Oklahoma soils and yielded a recovery of 99% of the ATP from added Escherichia coli cells. The extraction mixture was designed to minimize interference from soil-derived materials. The phosphoric acid provides acid to extract ATP and to inactivate proteins, and phosphate to saturate phosphate-binding sites. It also complexes or precipitates metal ions. The EDTA chelates metal ions, prevents inhibition of luciferase, and aids lysis of bacterial cells. The adenosine serves to saturate ATP binding-sites. Urea denatures proteins and prevents hydrogen bonding of the released ATP. DMSO, the Polytron treatment, and Zwittergent 3,10 remove cells from surfaces and lyse them. An internal standard of E. coli cells is used to determine efficiency of extraction and assay. When compared with the 12 best methods suggested by previous studies, the newly-formulated extractant and procedure yielded the greatest amount of ATP from soil.