Original article Effects of sulfadiazine-contaminated fresh and stored manure on a soil microbial community Ute Hammesfahr a , Anja Kotzerke b , Marc Lamshöft c , Berndt-Michael Wilke b , Ellen Kandeler d , Sören Thiele-Bruhn a, * a Soil Science, University of Trier, Campus II, D-54286 Trier, Germany b Institute of Ecology, Berlin University of Technology, Franklinstr. 29, D-10587 Berlin, Germany c Institute of Environmental Research, Technical University of Dortmund, Otto-Hahn-Str. 6, D-44221 Dortmund, Germany d Institute of Soil Science and Land Evaluation, University of Hohenheim, Emil-Wolff-Str. 27, D-70599 Stuttgart, Germany article info Article history: Received 7 June 2010 Received in revised form 6 October 2010 Accepted 8 October 2010 Available online 16 October 2010 Handling editor: Christoph Tebbe Keywords: Antibiotics Sulfadiazine Manure storage PLFA N mineralization abstract The response of soil microorganisms to manure contaminated by veterinary antibiotics is not well understood. Therefore, a 57-d incubation experiment was performed to investigate effects of sulfadiazine (SDZ) contaminated manure on soil microorganisms. Manure was either obtained directly from medi- cated pigs or subsequently stored for six month. We hypothesized that SDZ-contaminated manure changes functions and structural composition of soil microorganisms and that manure storage reduces antibiotic effects. Rates of potential nitrification and N mineralization as well as PLFA (phospholipid fatty acid) patterns were determined. Addition of uncontaminated manure to soil affected N cycle processes and the microbial community structure, and effects differed between fresh and stored manure. The rates of potential nitrification, ammonification and N mineralization and ratios of bacteria/fungi and gram- negative/gram-positive bacteria derived from PLFA were lower in soil treated with stored compared to fresh, uncontaminated manure. SDZ-contaminated manure affected N cycle processes with slight differences due to manure storage, whereas PLFA tot and the derived bacteria/fungi ratio were only reduced by stored, contaminated manure. SDZ reduced rates of nitrification and N mineralization, while ammonification increased. Effects of SDZ on soil microorganisms were significant although the bioavailable SDZ fraction (CaCl 2 -extractable) rapidly declined. We conclude that conventional manure storage is unsuited to reduce risks from sulfonamide antibiotics in the soil environment. Ó 2010 Elsevier Masson SAS. All rights reserved. 1. Introduction The use of antibiotics in livestock farming is common practice to prevent infectious diseases or to stimulate growth of domestic animals. Sulfadiazine (SDZ) is a sulfonamide antibiotic, inhibiting the dihydropteroate synthesis in the folic acid pathway and is widely used in pig production [1]. The SDZ is mainly excreted from the treated bodies and ends up in manure, while only 4% remain in medicated pigs [2]. Application of contaminated manure to soil results in residual antibiotic contamination; up to 90 mg kg 1 of extractable and consequently even higher amounts of total sulfonamides have been reported for agricultural soil [3]. Several studies on the fate of sulfonamides in soil suggested that effects on soil microbial biomass, structural composition and enzyme activities are likely to occur [4,5]. In several recent microcosm studies, the effects of such bacteriostatic antibiotics on microbial structure and function have been investigated. Effects of sulfonamide antibiotics on actual and potential microbial activities and the bacterial community structure were reported [6,7] and shifts from bacteria to fungi were observed [7,8]. In these studies, soil amendment with a nutrient source (glucose) was required to obtain antibiotic effects on microbial function and structure. Therefore, the effect of sulfonamides seemed to be linked to substrate addition, which is normally the case since manure or biosolids are the main carrier of antibiotics to soil. Manure is a common substrate used for fertilisation in agri- cultural ecosystems and stimulates growth of microorganisms through the high input of organic carbon and nutrients. Many studies determined an increase in the microbial growth caused by organic fertiliser [9]. Structural changes in the soil community have been determined by PLFA profiling and were mainly attrib- uted to indicators for gram-negative bacteria [10]. In addition, soil physiological properties, mobility and availability of antibiotics were influenced by manure addition to soil [11,12]. * Corresponding author. Tel.: þ49 651 2013923; fax: þ49 651 2013809. E-mail address: thiele@uni-trier.de (S. Thiele-Bruhn). Contents lists available at ScienceDirect European Journal of Soil Biology journal homepage: http://www.elsevier.com/locate/ejsobi 1164-5563/$ e see front matter Ó 2010 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.ejsobi.2010.10.004 European Journal of Soil Biology 47 (2011) 61e68