title: Land Spreading of Wastewaters from the Fruit-Packaging Industry and Potential Effects on Soil Microbes: Effects of the Antioxidant Ethoxyquin and Its Metabolites on Ammonia Oxidizers.
abstract: Thiabendazole (TBZ), imazalil (IMZ), ortho-phenylphenol (OPP), diphenylamine (DPA), and ethoxyquin (EQ) are used in fruit-packaging plants (FPP) with the stipulation that wastewaters produced by their application would be depurated on site. However, no such treatment systems are currently in place, leading FPP to dispose of their effluents in agricultural land. We investigated the dissipation of those pesticides and their impact on soil microbes known to have a key role on ecosystem functioning. OPP and DPA showed limited persistence (50% dissipation time [DT50], 0.6 and 1.3 days) compared to TBZ and IMZ (DT50, 47.0 and 150.8 days). EQ was rapidly transformed to the short-lived quinone imine (QI) (major metabolite) and the more persistent 2,4-dimethyl-6-ethoxyquinoline (EQNL) (minor metabolite). EQ and OPP exerted significant inhibition of potential nitrification, with the effect of the former being more persistent. This was not reflected in the abundance (determined by quantitative PCR [qPCR]) of the amoA gene of ammonia-oxidizing bacteria (AOB) and archaea (AOA). Considering the above discrepancy and the metabolic pattern of EQ, we further investigated the hypothesis that its metabolites and not only EQ were toxic to ammonia oxidizers. Potential nitrification, amoA gene abundance, and amoA gene transcripts of AOB and AOA showed that QI was probably responsible for the inhibition of nitrification. Our findings have serious ecological and practical implications for soil productivity and N conservation in agriculturally impacted ecosystems and stress the need to include metabolites and RNA-based methods when the soil microbial toxicity of pesticides is assessed.
authors.affiliation: Aristotle University of Thessaloniki, Faculty of Agriculture, Forestry and Natural Environment, Laboratory of Pesticide Science, Thessaloniki, Greece University of Thessaly, Department of Biochemistry and Biotechnology, Larisa, Greece.
authors.forename: Evangelia S
authors.initials: ES
authors.lastname: Papadopoulou
authors.affiliation: University of Thessaly, Department of Biochemistry and Biotechnology, Larisa, Greece.
authors.forename: Bella
authors.initials: B
authors.lastname: Tsachidou
authors.affiliation: University of Silesia, Department of Microbiology, Katowice, Poland.
authors.forename: Sławomir
authors.initials: S
authors.lastname: Sułowicz
authors.affiliation: Aristotle University of Thessaloniki, Faculty of Agriculture, Forestry and Natural Environment, Laboratory of Pesticide Science, Thessaloniki, Greece.
authors.forename: Urania
authors.initials: U
authors.lastname: Menkissoglu-Spiroudi
authors.affiliation: University of Thessaly, Department of Biochemistry and Biotechnology, Larisa, Greece dkarpouzas@bio.uth.gr.
authors.forename: Dimitrios G
authors.initials: DG
authors.lastname: Karpouzas
mesh_terms: D000641:Ammonia / Q000378:metabolism*; D000975:Antioxidants / Q000378:metabolism / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D005015:Ethoxyquin / Q000378:metabolism / Q000494:pharmacology*; D018857:Food Packaging; D005520:Food Preservatives / Q000378:metabolism / Q000494:pharmacology*; D005638:Fruit / Q000737:chemistry; D007220:Industrial Waste / Q000032:analysis; D010084:Oxidation-Reduction; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism / Q000494:pharmacology*; D062065:Wastewater / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000378:metabolism / Q000494:pharmacology
chemical_list: D000641:Ammonia; D000975:Antioxidants; D005015:Ethoxyquin; D005520:Food Preservatives; D007220:Industrial Waste; D012989:Soil Pollutants; D062065:Wastewater; D014874:Water Pollutants, Chemical