Influence of microbial and enzymatic activities on immobilisation of xenobiotics in soil organo-clay complexes

有机-粘土复合体是土壤中不可提取残留物的主要汇。尽管已知这种掺入主要由微生物活性辅助，但确切的机制仍不清楚。胞外酶活性与活生物量贡献的竞争正在讨论中。因此，我们将研究微生物和稳定的胞外酶在土壤有机粘土颗粒共价固定两种外源性物质--内分泌干扰物353-壬基酚过程中的作用和参与（p-353-NP）和杀真菌剂甲霜灵。（a）整个土壤，（B）天然有机-粘土复合物和（c）模型有机-粘土复合物，均为灭菌和非灭菌形式。这种策略将允许从那些胞外酶的活的微生物的影响分离，并使微生物辅助粘合过程的详细表征。NER形成后将进行放射性分析，使用14 C-异生物质和定量，对映选择性以及化合物特定同位素分析，使用未标记的物质。此外，还将测试特定酶（过氧化物酶、酚氧化酶）形成NER的潜力，从而验证胞外酶活性是外源性物质共价固定到土壤中有机-粘土复合物的主要驱动力的假设。

Organo-clay complexes are a major sink of non-extractable residues in soil. Although it is known that this incorporation is dominantly assisted by microbial activity, the exact mechanism remains unclear. The competition of extracellular enzyme activity versus contribution of living biomass is under discussion. Therefore we will study the role and participation of microorganisms as well as stabilized extracellular enzymes in the covalent immobilization process of two xenobiotics on organo-clay particles in soil, i.e. the endocrine disrupting compound 353-nonylphenol (p-353-NP) and the fungicide metalaxyl.Three systems are investigated: (a) whole soil, (b) native organo-clay complexes and (c) model organo-clay complexes, both in sterilized and non-sterilized form. This strategy will allow the separation of effects from living micororganisms from those of extracellular enzymes and enables the detailed characterisation of microbial assisted bonding processes. NER formation will be followed by radioanalyses using 14C-xenobiotics and quantitative, enantioselective as well as compound specific isotope analyses using unlabelled substances. Further on the potential of specific enzymes (peroxidase, phenoloxidase) for NER formation will be tested.We will thus test the hypothesis that extracellular enzyme activities are the main driving force for covalent immobilization of xenobiotics to organo-clay complexes in soils.