Fluorescein Diacetate Hydrolysis as a Measure of Total Microbial Activity in Soil and Litter

TLDR

Spectrophotometric determination of fluorescein diacetate hydrolysis provides a simple, sensitive, and rapid method for measuring microbial activity in soil and litter. FDA hydrolysis was examined in soil and straw over 3 h, showing a linear increase with soil addition and a correlation with respiration across soil layers. FDA hydrolysis increased linearly with added Fusarium culmorum mycelium or Pseudomonas denitrificans biomass, and acetone effectively terminated the reaction.

Abstract

Spectrophotometric determination of the hydrolysis of fluorescein diacetate (FDA) was shown to be a simple, sensitive, and rapid method for determining microbial activity in soil and litter. FDA hydrolysis was studied in soil and straw incubated for up to 3 h. Hydrolysis was found to increase linearly with soil addition. FDA hydrolysis by pure cultures of Fusarium culmorum increased linearly with mycelium addition both in shake cultures and after inoculation into sterile soil. FDA hydrolysis by Pseudomonas denitrificans increased linearly with biomass addition. The FDA hydrolytic activities in soil samples from different layers of an agricultural soil were correlated with respiration. Acetone was found to be suitable for terminating the reaction.