Natural Resources, School of


Date of this Version

Spring 4-21-2016


Hoehn, E.C. (2016). Improved microplate fluorometric soil enzyme assay for β-glucosidase detection.UNL Digital Commons. 1-102.


A THESIS Present to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Natural Resource Sciences, Under the Supervision of Professor Daniel D Snow. Lincoln, Nebraska: May, 2016

Copyright © 2016 Emily C. Hoehn


Soil microbes produce extracellular enzymes responsible for degrading complex organic compounds to release energy and nutrients. Measurement of soil enzymes can be considered an indicator of soil health and microbial community composition because of its sensitivity to agricultural and management practices. Fluorescence enzyme assays tend to be more sensitive than spectrophotometric (ie. colorimetric) assays and a 96-well plate has the potential capacity for high-throughput use. Development of a newly modified enzyme assay using fluorometric (4-methylumbelliferone), automated pipetting system and sonication, as well as a reduction in replicates allows for a higher sample throughput rate suitable for service laboratory use. The newly modified enzyme assay was applied to a long-term cropping system and varying fertilizer nitrogen management to determine the use of air-dried versus fresh soil enzyme activity. No significant difference was found in air-dried and fresh soils, but fertilizer N differences were only apparent under air-dried conditions. The positive linear relationship between β-glucosidase and grain yield support the use of enzymes as a soil quality indicator.

Adviser: Daniel D Snow