Aslam Sohaib, Arslan Muhammad, Nowak Karolina M
Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research - UFZ, Permoserstr. 15, 04318 Leipzig, Germany.; Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstr. 15, 04318 Leipzig, Germany.; Department of Environmental Sciences, Forman Christian College (A Chartered University), Ferozepur Road, 54600 Lahore, Pakistan.
Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada.
Sci Total Environ. 2023 Oct 28:168206. doi: 10.1016/j.scitotenv.2023.168206.
Widely-used glyphosate may produce aminomethylphosphonic acid (AMPA), glycine and sarcosine. To date, little is known about effects of these degradation products on soil microorganisms and their potential degraders. Here, we incubated a soil spiked either with 2-C-glyphosate, C-AMPA, C-sarcosine or C-glycine for 75 days. Respiration (CO) and mineralization rates of the compound (CO) were estimated in addition to phospholipid fatty acids (PLFAs and C-PLFAs) as biomarkers to identify four groups of microorganisms (Gram-negative & Gram-positive bacteria, actinobacteria, fungi). 16S/ITS rRNA amplicon sequencing was also conducted to identify the microbial community at the phylum and genus level. The CO and CO rates were highest on day 2 in all treatments, as follows: glycine (CO: 1.09 μmol g; CO: 18 %) > sarcosine (CO: 0.89 μmol g; CO: 8.5 %) > glyphosate (CO: 0.67 μmol g; CO: 2.2 %) > AMPA (CO: 0.53 μmol g; CO: 0.3 %). Both the PLFAs and C-PLFAs were highest in glycine (PLFAs: 0.054-0.047 μmol g; C-PLFAs: 0.2-0.4 %) and glyphosate (PLFAs: 0.049-0.047 μmol g; C-PLFAs: 0.1-0.3 %) treatments compared to sarcosine and AMPA treatments. Gram negative bacteria were major microbial group of soil microbiome as well as primary degraders of all compounds. In contrast, Gram-positive bacteria, actinobacteria and fungi could have been consumers of primary degraders. Certain genera e.g. Gemmatimonas, Arenimonas and Massilia showed increased abundance in certain treatments indicating their potential involvement in biodegradation. Based on similar time-dependent microbial activity and shifts in abundances of (C-)PLFAs and 16S rRNA genera, we deduced that glyphosate was mainly degraded to glycine, and presumably at elevated amounts. We reported for the first time that the glycine presumably altered microbial activity and community composition rather than glyphosate directly. Future studies should thus also consider the potential impacts of degradation products of the parent compound on soil microbiomes.
广泛使用的草甘膦可能会产生氨甲基膦酸（AMPA）、甘氨酸和肌氨酸。迄今为止，对于这些降解产物对土壤微生物及其潜在降解菌的影响知之甚少。在此，我们将添加了2-C-草甘膦、C-AMPA、C-肌氨酸或C-甘氨酸的土壤进行了75天的培养。除了将磷脂脂肪酸（PLFAs和C-PLFAs）作为生物标志物来鉴定四类微生物（革兰氏阴性菌和革兰氏阳性菌、放线菌、真菌）外，还估算了化合物的呼吸作用（CO₂）和矿化率（CO₂）。还进行了16S/ITS rRNA扩增子测序，以在门和属水平上鉴定微生物群落。在所有处理中，CO₂和CO₂速率在第2天最高，如下所示：甘氨酸（CO₂：1.09 μmol g⁻¹；CO₂：18%）＞肌氨酸（CO₂：0.89 μmol g⁻¹；CO₂：8.5%）＞草甘膦（CO₂：0.67 μmol g⁻¹；CO₂：2.2%）＞AMPA（CO₂：0.53 μmol g⁻¹；CO₂：0.3%）。与肌氨酸和AMPA处理相比，甘氨酸（PLFAs：0.054 - 0.047 μmol g⁻¹；C-PLFAs：0.2 - 0.4%）和草甘膦（PLFAs：0.049 - 0.047 μmol g⁻¹；C-PLFAs：0.1 - 0.3%）处理中的PLFAs和C-PLFAs均最高。革兰氏阴性菌是土壤微生物群落的主要微生物类群，也是所有化合物的主要降解菌。相比之下，革兰氏阳性菌、放线菌和真菌可能是主要降解菌的消费者。某些属，如芽单胞菌属、沙漠单胞菌属和马赛菌属，在某些处理中丰度增加，表明它们可能参与了生物降解。基于类似的随时间变化的微生物活性以及（C-）PLFAs和16S rRNA属丰度的变化，我们推断草甘膦主要降解为甘氨酸，且推测其含量有所增加。我们首次报道，可能是甘氨酸而非草甘膦直接改变了微生物活性和群落组成。因此，未来的研究也应考虑母体化合物的降解产物对土壤微生物群落的潜在影响。
