Ecological Indicators 23 (2012) 482–490 Contents lists available at SciVerse ScienceDirect Ecological Indicators jo ur n al homep ag e: www.elsevier.com/locate/ecolind The FungiResp method: An application of the MicroResp TM method to assess fungi in microbial communities as soil biological indicators Meriem Ben Sassi a,b , Jeanne Dollinger a,b , Pierre Renault a,b , Ahmed Tlili c , Annette Bérard a,b,∗ a INRA, UMR1114 EMMAH, F-84914 Avignon, France b UAPV, UMR1114 EMMAH, F-84914 Avignon, France c Institute of Freshwater Ecology and Inland Fisheries, Alte Fischerhütte 2, Neuglobsow, Germany a r t i c l e i n f o Article history: Received 23 January 2012 Received in revised form 3 May 2012 Accepted 7 May 2012 Keywords: Substrate-induced respiration Selective inhibition MicroResp TM Soil microbial catabolic structure Soil fungal catabolic structure a b s t r a c t Soil ecosystem services need to monitor soil quality in terms of soil functions. This need in turn requires functional indicators. Microbial functional diversity offers a way to characterize soil quality and any changes to it. Among soil microbial communities, fungi play a critical role in organic matter decomposition and nutrient cycling in soil by decomposing complex substrates, but only a few studies have focused on the function of soil fungal communities. We have developed a protocol based on substrate-induced respiration using the MicroResp TM technique combined with a selective inhibition (SI) procedure to characterize the fungal biomass and catabolic profiles for soil microbial and fungal communities: the FungiResp method. After comparisons with oxytetracycline, we chose bronopol as a bactericide to extend the FungiResp protocol. An optimal bronopol concentration of 78 g g -1 soil was selected for the four soils tested to minimize the risk of inhibiting non-target communities (fungi). We used this convenient, miniaturized method to compare different soils and different perturbations (drought and heat). The FungiResp method gave further data on the fungal part of the microbial substrate-induced respiration in these different contexts. Also, the catabolic structure of microbial and fungal communities measured as pattern of substrate utilization (CLPPs) enabled us to contrast the functional contributions of the decomposer groups in the different soils studied and highlight the functional impacts of the different perturbations applied to them. © 2012 Elsevier Ltd. All rights reserved. 1. Introduction Soil faces a broad range of threats from human activities and global change. These pressures may degrade it through an increase in erosion, contamination, sealing, compaction, salin- ization, and loss of organic matter, structure and biodiversity (Commission of the European Communities, 2002). Soil ecosys- tem services (Millennium Ecosystem Assessment, 2005), need to monitor soil quality in terms of soil functions, which demands func- tional indicators (Romaniuk et al., 2011; Ritz et al., 2009). Doran and Zeiss (2000) suggested complementary criteria of soil bioindi- cators: they should be sensitive to variations in management and climate change, well correlated with beneficial soil func- tions, useful for elucidating ecosystem processes, comprehensible and useful to land managers and finally easy and inexpensive to measure. Soil microbial communities are extremely diverse in their composition and play an essential role in nutrient cycling ∗ Corresponding author at: INRA, UMR1114 EMMAH, F-84914 Avignon, France. E-mail address: annette.berard@paca.inra.fr (A. Bérard). functions such as organic matter decomposition and mineraliza- tion, nutrient mobilization and carbon sequestration (Reynolds et al., 2003; Strickland and Rousk, 2010). Recent studies have sought to assess the importance of microbial diversity, micro- bial community composition and interactions between microbial species for soil functioning (Bell et al., 2005). Also, the loss of microbial functions is an indicator of decrease in soil quality (Chapman et al., 2007). Hence it is useful to assess microbial functional diversity to characterize soil quality and any decrease it may undergo. Community-level physiological profiles (CLPPs), usually assessed by carbon substrate utilization, are good tools to evaluate the microbial functional diversity of a soil, and have been widely implemented with the Biolog method (Calbrix et al., 2005). Alternative microplate methods derived from Biolog were devised for fungi (Buyer et al., 2001; Dobranic and Zak, 1999). However, these techniques are limited to the assessment of the extractable and cultivable fraction of soil microbial com- munities, and need long incubation times to induce microbial selection and growth. A respirometric technique based on the analysis of the substrate-induced respiration (SIR) response of whole-soil samples was investigated with a multiple carbon- source substrate for CLPP by Degens and Harris (1997). However, 1470-160X/$ – see front matter © 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ecolind.2012.05.002