UFZ - Helmholtz-Centre for Environmental Research, Department of Environmental Biotechnology, Permoserstr. 15, 04318, Leipzig, Germany; Institute of Landscape Ecology, University of Münster, Heisenbergstr. 2, 48149, Münster, Germany; Pontifical Bolivarian University, Environmental Engineering Faculty, Km 7 Vía Piedecuesta, Bucaramanga, Colombia.
UFZ - Helmholtz-Centre for Environmental Research, Department of Environmental Biotechnology, Permoserstr. 15, 04318, Leipzig, Germany.
Environ Pollut. 2022 Mar 15;297:118790. doi: 10.1016/j.envpol.2022.118790. Epub 2022 Jan 8.
Glyphosate can be degraded by soil microorganisms rapidly and is impacted by temperature and soil properties. Enhanced temperature and total organic carbon (TOC) as well as reduced pH increased the rate of CN-glyphosate conversion to CO and biogenic non-extractable residues (bioNERs) in a Haplic Chernozem (Muskus et al., 2019) and in a Humic Cambisol (Muskus et al., 2020). To date; however, the combined effect of temperature and TOC or pH on microbial community composition and glyphosate degraders in these two soils has not been investigated. Phospholipid fatty acid [PLFA] biomarker analysis combined with C labeling was employed to investigate the effect of two soil properties (pH, TOC) and of three temperatures (10 °C, 20 °C, 30 °C) on soil microorganisms. Before incubation, the properties of a Haplic Chernozem and a Humic Cambisol were adjusted to obtain five treatments: (a) Control (Haplic Chernozem: 2.1% TOC and pH 6.6; Humic Cambisol: 3% TOC and pH 7.0), (b) 3% TOC (Haplic Chernozem) or 4% TOC (Humic Cambisol), (c) 4% TOC (Haplic Chernozem) or 5% TOC (Humic Cambisol), (d) pH 6.0 (Haplic Chernozem) or pH 6.5 (Humic Cambisol), and (e) pH 5.5 for both soils. All treatments were amended with 50 mg kg glyphosate and incubated at 10 °C, 20 °C or 30 °C. We observed an increase in respiration, microbial biomass and glyphosate mineralization with incubation temperature. Although respiration and microbial biomass in the Humic Cambisol was higher, the microorganisms in the Haplic Chernozem were more active in glyphosate degradation. Increased TOC shifted the microbiome and the C-glyphosate degraders towards Gram-positive bacteria in both soils. However, the abundance of C-PLFAs indicative for the starvation of Gram-negative bacteria increased with increasing TOC or decreasing pH at higher temperatures. Gram-negative bacteria thus may have been involved in earlier stages of glyphosate degradation.
草甘膦可被土壤微生物迅速降解，并受温度和土壤特性的影响。在黑钙土（Muskus 等人，2019 年）和腐殖质钙层土（Muskus 等人，2020 年）中，增强的温度和总有机碳（TOC）以及降低的 pH 值均提高了 CN-草甘膦向 CO 和生物非提取残留（bioNERs）的转化速率。然而，迄今为止，尚未研究温度和 TOC 或 pH 值对这两种土壤中微生物群落组成和草甘膦降解菌的综合影响。采用磷脂脂肪酸 [PLFA] 生物标志物分析结合 C 标记法，研究了两种土壤特性（pH 值、TOC）和三种温度（10°C、20°C、30°C）对土壤微生物的影响。在培养之前，调整黑钙土和腐殖质钙层土的性质，以获得五种处理：（a）对照（黑钙土：TOC 为 2.1%，pH 值为 6.6；腐殖质钙层土：TOC 为 3%，pH 值为 7.0），（b）3%TOC（黑钙土）或 4%TOC（腐殖质钙层土），（c）4%TOC（黑钙土）或 5%TOC（腐殖质钙层土），（d）pH 值为 6.0（黑钙土）或 pH 值为 6.5（腐殖质钙层土），以及（e）两种土壤的 pH 值为 5.5。所有处理均添加 50mgkg 草甘膦，并在 10°C、20°C 或 30°C 下培养。我们观察到随着培养温度的升高，呼吸作用、微生物生物量和草甘膦矿化作用增加。尽管腐殖质钙层土的呼吸作用和微生物生物量较高，但黑钙土中的微生物在草甘膦降解方面更为活跃。TOC 的增加使两种土壤中的微生物组和 C-草甘膦降解菌向革兰氏阳性菌转移。然而，随着 TOC 的增加或在较高温度下 pH 值的降低，指示革兰氏阴性菌饥饿的 C-PLFA 的丰度增加。因此，革兰氏阴性菌可能参与了草甘膦降解的早期阶段。
