Improvement of pesticide mineralization in on-farm biopurification systems by bioaugmentation with pesticide-primed soil

RESEARCH ARTICLE Improvement of pesticide mineralization in on-farm biopuri¢cation systems by bioaugmentation with pesticide-primed soil Kristel Sniegowski1, Karolien Bers1, Kris Van Goetem1, Jaak Ryckeboer1, Peter Jaeken2, Pieter Spanoghe3 & Dirk Springael1 1 Division of Soil and Water management, Katholieke Universiteit Leuven, Heverlee, Belgium; 2Ecology Department, Proefcentrum Fruitteelt vzw, Sint-Truiden, Belgium; and 3Laboratory of Crop Protection Chemistry, Ghent University, Ghent, Belgium Present address: Peter Jaeken, Phytofar, A. Reyerslaan 80, 1030 Brussels, Belgium. Received 28 June 2010; revised 3 December 2010; accepted 3 December 2010. Final version published online 13 January 2011. MICROBIOLOGY ECOLOGY DOI:10.1111/j.1574-6941.2010.01031.x Editor: Kornelia Smalla Keywords biopurification system; pesticide-primed soil; bioaugmentation; linuron mineralization; Variovorax. Abstract Microcosms were used to examine whether pesticide-primed soils could be preferentially used over nonprimed soils for bioaugmentation of on-farm biopurification systems (BPS) to improve pesticide mineralization. Microcosms containing a mixture of peat, straw and either linuron-primed soil or nonprimed soil were irrigated with clean or linuron-contaminated water. The lag time of linuron mineralization, recorded for microcosm samples, was indicative of the dynamics of the linuron-mineralizing biomass in the system. Bioaugmentation with linuronprimed soil immediately resulted in the establishment of a linuron-mineralizing capacity, which increased in size when fed with the pesticide. Also, microcosms containing nonprimed soil developed a linuron-mineralizing population, but after extended linuron feeding. Additional experiments showed that linuron-mineralization only developed with some nonprimed soils. Concomitant with the increase in linuron degradation capacity, targeted PCR-denaturing gradient gel electrophoresis showed the proliferation of a Variovorax phylotype related to the linuron-degrading Variovorax sp. SRS16 in microcosms containing linuronprimed soil, suggesting the involvement of Variovorax in linuron degradation. The correlation between the appearance of specific Variovorax phylotypes and linuron mineralization capacity was less clear in microcosms containing nonprimed soil. The data indicate that supplementation of pesticide-primed soil results in the establishment of pesticide-mineralizing populations in a BPS matrix with more certainty and more rapidly than the addition of nonprimed soil. Introduction Since 1940, pesticides are intensively used worldwide. An important environmental issue of pesticide use is the pollution of ground and surface water as a result of either diffuse (run-off, percolation and spray drift) or point contamination (direct losses through spillage and leakages). Recent studies showed that direct losses account for 40–90% of the surface water pollution (De Wilde et al., 2007). To minimize direct pesticide losses, the installation of biopurification systems (BPS) to treat pesticide-contaminated wastewater on the farm yard has been proposed (Torstensson & del Pilar Castillo, 1997; Vischetti et al., 2004; De Wilde et al., 2007). In on-farm BPS, the contaminated water is conducted over a solid matrix, called a biomix, which is composed of a c 2011 Federation of European Microbiological Societies Published by Blackwell Publishing Ltd. All rights reserved mixture of various materials, for example straw, peat and soil, in which biodegradation and sorption result in pesticide removal. BPS are considered a simple, low-cost, practical and labor-extensive approach for farmers to treat pesticide-contaminated wastewater on the farm. Despite the high pesticide removal percentage observed in BPS (Fogg et al., 2003a, b, 2004; Pigeon et al., 2005), degradation remains poor for some pesticides (Fogg et al., 2003a, 2004). Moreover, a rapid complete degradation is advised to avoid possible toxicity effects of accumulated contaminants (Henriksen et al., 2003), aging (Johannesen et al., 2003; Zhao et al., 2003) and the occurrence of mobile and toxic metabolites (Coppola et al., 2007). In addition, degradation during start-up of the system is poor (Fogg et al., 2004) because the appropriate microorganisms need to proliferate FEMS Microbiol Ecol 76 (2011) 64–73 Correspondence: Kristel Sniegowski, Division of Soil and Water management, Katholieke Universiteit Leuven, Kasteelpark Arenberg 20, 3001 Heverlee, Belgium. Tel.: 132 16 32 16 04; fax: 132 16 19 97; e-mail: 65 Pesticide-primed soil to improve on-farm biopurification FEMS Microbiol Ecol 76 (2011) 64–73 ing isolates originating from linuron-treated soils, including the linuron-primed soil used in this study, almost exclusively belong to the genus Variovorax (Dejonghe et al., 2003; Sorensen et al., 2005; Breugelmans et al., 2007), the number of Variovorax and composition of the Variovorax community within the BMs was monitored by means of targeted molecular techniques. Materials and methods Pesticides used Linuron [3-(3,4-dichlorophenyl)-1-methoxy-1-methyl urea] (purity, 99.5%) was purchased from Sigma Aldrich (Belgium). [phenyl-U-14C] linuron (16.93 mCi mmol 1, radiochemical purity 4 95%) was obtained from Izotop, Hungary. BM set-ups BM were set up in glass cylinders (height 10 cm; diameter 4 cm) containing a glass filter positioned at 8 cm depth and filled with the appropriate mixture of soil, peat and straw (Table 1). The linuron-primed soil (soil L) was sampled from the A-horizon of a potato field in Halen, Belgium, in April 2005. The field had been treated for several years with linuron and was shown to contain a linuron-mineralizing microbial community (Breugelmans et al., 2007). Non-linuronprimed soils were obtained from seven different locations representing four different ecosystems, i.e. garden (soils G1 and Table 1. Overview of the different BM set-ups operated in this study Set-up Origin soil Moisture LinuronLinuron content primed soil treatment (w/w%) pH (  SD) Experiment 1: mixture: straw (25 vol%); peat (25 vol%); soil (50 vol%) Agriculture 1 56.12 6.20 (  0.12) L Agriculture 1 1 60.52 6.20 (  0.12) L1 C Construction 48.00 6.05 (  0.22) site Construction 1 48.14 6.05 (  0.22) C1 site Experiment 2: mixture: straw (37.5 vol%); peat (37.5 vol%); soil (25 vol%) w No soil 1 217.78 5.11 (  0.10) O1 Agriculture 1 1 89.52 5.44 (  0.26) L1 Construction 1 71.03 5.49 (  0.21) C1 site Agriculture 1 42.67 5.56 (  0.55) A1 1 A1 Agriculture 1 34.64 5.09 (  0.15) 2 Forest 1 82.33 5.61 (  0.10) F1 1 F1 Forest 1 57.54 4.87 (  0.11) 2 Garden 1 74.19 5.43 (  0.05) G1 1 G1 Garden 1 42.25 5.38 (  0.30) 2 1 and indicate treatment with and without linuron, respectively. Straw: 50 vol%, peat: 50 vol%, soil: 0 vol%. w 2011 Federation of European Microbiological Societies Published by Blackwell Publishing Ltd. All rights reserved c in the biomix before maximum degradation rates a (...truncated)