New methods hold the promise for providing answers to previously intractable problems in microbial ecology. This project will develop new technologies needed to determine where nitrification occurs in acidic forest soils: (a) polymerase chain reaction (PCR) to quantify nitrifier populations in small soil samples using primers based on the ammonium monooxygenase chromosomal gene and regions of 16S ribosomal DNA specific to ammonia- oxidizing strains and (b) microelectrodes to measure pH gradients in the soil. Autotrophic nitrification may occur in alkaline microenvironments within an acid forest soil developed under red alder (Alnus rubra). Microgradients of pH and populations of nitrifiers (by PCR) will be determined. Methods developed will be applicable to improvements in forestry and agricultural practices as well as to the fundamental study of nutrient dynamics in soils.
