Abstract

Under laboratory conditions, the decomposition of glyphosate with the formation of aminomethylphosphonic acid (AMPA) and its effect on the total abundance of bacteria and fungi as well as the number of copies of genes encoding the enzymes C–P lyase of α-proteobacteria (phnJ), acid and alkaline phosphatase (phoC and phoD) and Fe protein of nitrogenase (nifH) in agro-sod-podzolic soil (Epialbic Retisol) were determined. It was shown that when applying glyphosate in recommended doses (5–10 mg/kg), only 5–7% of the introduced herbicide were detected after 14 days, but when the dose was increased to 100 mg/kg, this value increased up to 23%. Decreasing the rate of the herbicide degradation was observed only during the first week of incubation and was accompanied by a decrease in the number of copies of the phoC, phoD, and nifH genes and an increase in the abundance of fungi. The obtained results indicate that glyphosate was mainly degraded by means of C–P bond breaking and the formation of phosphates, and also suggest possible inhibition of the nitrogen fixation process. It is shown that at an application dose of glyphosate of 100 mg/kg may lead to the accumulation of AMPA, the first metabolite of the herbicide degradation pathway, formed after the C–N bond break. Bioassay using wheat showed that when applying glyphosate at a dose of 100 mg/kg, an inhibition of plant development was observed: the length of the roots and the biomass of the shoots reduced by 60 and 20% compared to the control, respectively. Based on the data obtained, it was proposed to use the reduction in the content of copies of the phoC gene and the increase in the number of copies of ITS rRNA as indicators of the predominant decomposition of glyphosate through the sarcosine pathway. The decrease in the number of copies of ITS rRNA gene by 40% or more can be used as an indicator of the possibility of AMPA accumulation during glyphosate degradation.

中文翻译：

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短期模型试验条件下草甘膦的降解及其对土壤-土壤-土壤的微生物群落的影响

摘要

在实验室条件下，草甘膦的分解与氨基甲基膦酸（AMPA）的形成及其对细菌和真菌总丰度的影响，以及对编码α-蛋白细菌C–P裂解酶的基因的拷贝数的影响（phnJ），酸性和碱性磷酸酶（phoC和phoD）和氮蛋白的铁蛋白（nifH）在土壤-土壤-坡地土壤中（Epialbic Retisol）进行了测定。结果表明，以推荐剂量（5–10 mg / kg）施用草甘膦时，在14天后仅检测到引入除草剂的5–7％，但是当剂量增加至100 mg / kg时，该值增加至23％。仅在孵育的第一周才观察到除草剂降解速度的降低，并伴随着phoC，phoD和nifH拷贝数的减少。基因和真菌丰度的增加。获得的结果表明，草甘膦主要通过C–P键断裂和磷酸盐的形成而降解，并且还暗示可能抑制固氮过程。结果表明，在100 mg / kg的草甘膦剂量下，可能导致AMPA的积累，AMPA是除草剂降解途径的第一个代谢产物，在C–N键断裂后形成。使用小麦的生物测定表明，当以100 mg / kg的剂量施用草甘膦时，观察到对植物发育的抑制作用：与对照相比，根的长度和枝条的生物量分别减少了60％和20％。根据获得的数据，建议减少phoC副本的内容基因和ITS rRNA拷贝数的增加表明草甘膦通过肌氨酸途径主要分解。ITS rRNA基因拷贝数减少40％或更多可被用作草甘膦降解期间AMPA积累的可能性的指标。