Fluorescein diacetate (FDA) hydrolytic activity of forest soil

Authors: Jana Gáfriková 1    Peter Kuric 1   
1 Prírodovedecká fakulta Univerzity Komenského, Katedra pedológie, Bratislava, Slovenská republika, Bratislava,   
Year: 2017
Section: Ecology and Environmental Sciences
Abstract No.: 1564
ISBN: 978-80-972360-1-4

Soil microbial activity, reflected in soil enzyme activity, is widely used indicator of soil microbial quality as well as organic matter turnover. Fluorescein diacetate (FDA) hydrolysis is commonly accepted simple, sensitive and accurate method for estimating soil microbial activity [1, 2]. The enzymes involved in FDA hydrolysis, including non-specific esterases, proteases and lipases, are integral part of living cells or released by decomposing microorganisms, especially bacteria and fungi [3].

Topsoil (10 cm) of Cambic podzol was collected in July 2016 at Tatra National Park from area affected by windstorm in 2004. After the disturbance, wooden debris from the area was not extracted (NEX). Nowadays, self-regenerated plot is in process of secondary succession, mainly covered by seedlings and young Picea abies and Rubus idaeus. Soil samples consisted of nine different soils where dominant vegetation was P.abies (NEX-P) or R.idaeus (NEX-R).

FDA activity was estimated from 1.0 g of fresh soil. The procedure included incubation with K-phosphate buffer (60mM, pH 7.6) and FDA solution on end-over-end shaker at 25°C for 30 min. Released fluorescein was extracted by chloroform-methanol extractant and measured spectrofotometrically at 490 nm.

A hydrolytic capacity of soil, expressed as FDA activity, ranged for NEX-R from 0.20 to 0.36 µg fluorescein/g dry soil/0.5 h and for NEX-P from 0.19 to 0.37 µg fluorescein/g dry soil/0.5 h. The average value for NEX-R was 0.30 µg fluorescein/g dry soil/0.5 h and for NEX-P 0.27 µg fluorescein/g dry soil/0.5 h.

[1] Gillian, A., Duncan, H. 2001. Developmnet of a sensitive and rapid method for measure of total microbial activity using FlouresceinDiacetate (FDA) in a range of soils. Soil Biology & Biochemistry 33. p 943-951.
[2] Green, V.S., Stott, D.E., Diack, M. 2006. Assay for fluorescein diacetate hydrolytic activity: Optimization for soil samples. Soil Biology & Biochemistry 38. p 693-701.
[3] Schnürer, J.,Rosswall, T. 1982. Fluorescein Diacetate Hydrolysis as a Measure of Total Microbial Activity in Soil and Litter. Applied and Environmental Microbiology. p 1256-1261.