Kerstin Hund-Rinke, Anna Hümmler, Ruben Schlinkert, Franziska Wege & Gabriele Broll - Environmental Sciences Europe volume 31, Article number: 86 (2019)
Before chemicals, pesticides and biocides are registered and approved, their effects on soil microorganisms must be tested, specifically their impact on nitrogen transformation. Following a request from the European Food Safety Authority (EFSA), the Panel on Plant Protection Products and their Residues provided an opinion document evaluating the science behind the risk assessment of plant protection products in the context of soil-dwelling organisms. The EFSA document concludes that the most relevant community-based microbial test systems should cover the widest possible range of metabolic processes without compromising test sensitivity. The EFSA document refers to the MicroResp test system, stating that although it has not been used to study the effects of pesticides on soil microbial processes, its capability should be investigated in the future. In the scope of harmonization approaches, the recommendations in the EFSA document covering pesticides could also influence the risk assessment and regulation of other kinds of chemicals, including silver nanomaterials. We therefore used the silver nanomaterial NM-300K as a model substance to evaluate the sensitivity of three functional tests covering the activities of different microbial fractions: (1) the potential ammonium oxidation (PAO) test, which considers the first step in nitrification; (2) the MicroResp test, which determines respiratory activity by measuring CO2 evolution; and (3) a colorimetric test system for exoenzyme activity. We also surveyed bacterial 16S rRNA sequence diversity by next-generation sequencing (NGS).
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