Chair of Geobiotechnology, Technische Universität Berlin, Ackerstraße 76, 13355 Berlin, Germany; Helmholtz-Centre for Environmental Research - UFZ, Department of Environmental Biotechnology, Permoserstr. 15, 04318 Leipzig, Germany.
Bayer CropScience AG, Alfred-Nobel-Str. 50, 40789 Monheim am Rhein, Germany.
Environ Pollut. 2018 Nov;242(Pt A):769-777. doi: 10.1016/j.envpol.2018.07.049. Epub 2018 Jul 17.
Bromoxynil is a widely used nitrile herbicide applied to maize and other cereals in many countries. To date, still little is known about bromoxynil turnover and the structural identity of bromoxynil non-extractable residues (NER) which are reported to occur in high amounts. Therefore, we investigated the microbial turnover of C-labeled bromoxynil for 32 days. A focus was laid on the estimation of biogenic NER based on the turnover of C into amino acids (AA). At the end, 25% of C-bromoxynil equivalents were mineralized, 2% assigned to extractable residues and 72.5% to NER. Based on 12% in the C-total AA and an assumed share of AA of 50% in microbial biomass we arrived at 24% of total C-biogenic NER. About 33% of the total C-NER could thus be explained by C-biogenic NER; 67% was unknown and by definition xenobiotic NER with potential for toxicity. The C label from C-bromoxynil was mainly detected in the humic acids (28.5%), but significant amounts were also found in non-humics (17.6%), fulvic acids (13.2%) and humins (12.7%). The C-total amino acids hydrolyzed from humic acids, humins and fulvic acids amounted to 5.2%, 6.1% and 1.2% of C-bromoxynil equivalents, respectively, corresponding to total C-biogenic NER amounts of 10.4%, 12.2% and 2.4%. The humins contained mostly C-biogenic NER, whereas the humic and fulvic acids may be dominated by the xenobiotic NER. Due to the high proportion of unknown C-NER and particularly in the humic and fulvic acids, future studies should focus on the detailed characterization of these fractions.
溴苯腈是一种广泛使用的腈类除草剂，用于许多国家的玉米和其他谷物。迄今为止，人们对溴苯腈的转化以及据报道大量存在的溴苯腈不可提取残留（NER）的结构身份知之甚少。因此，我们研究了 32 天 C 标记的溴苯腈的微生物转化。重点是基于 C 转化为氨基酸（AA）来估计生物产生的 NER。最后，25%的 C-溴苯腈当量被矿化，2%分配到可提取残留，72.5%分配到 NER。基于 C 总 AA 中的 12%和假设微生物生物量中 AA 占 50%，我们得出总 C 生物产生的 NER 占 24%。因此，大约 33%的总 C-NER 可以用 C 生物产生的 NER 来解释；67%是未知的，根据定义是具有毒性的异生物质 NER。C 标记的 C-溴苯腈主要存在于腐殖酸（28.5%）中，但在非腐殖酸（17.6%）、富里酸（13.2%）和腐黑物（12.7%）中也发现了大量 C 标记的 C-溴苯腈。从腐殖酸、腐黑物和富里酸水解的 C 总氨基酸分别相当于 C-溴苯腈当量的 5.2%、6.1%和 1.2%，相当于总 C 生物产生的 NER 量为 10.4%、12.2%和 2.4%。腐黑物主要含有 C 生物产生的 NER，而腐殖酸和富里酸可能以异生物质 NER 为主。由于未知的 C-NER 比例较高，特别是在腐殖酸和富里酸中，未来的研究应集中在这些部分的详细特征描述上。
