Maharana Bhumika, Mahalle Sejal, Bhende Rahul, Dafale Nishant A
Environmental Biotechnology & Genomics Division, CSIR-National Environmental Engineering Research Institute (CSIR-NEERI), Nehru Marg, Nagpur, 440020, India.
Appl Biochem Biotechnol. 2025 Jan;197(1):73-93. doi: 10.1007/s12010-024-05033-y. Epub 2024 Aug 3.
The residual pesticides in soil can affect the natural microbiome composition and genetic profile that drive nutrient cycling and soil fertility. In the present study, metagenomic approach was leveraged to determine modulations in nutrient cycling and microbial composition along with connected nexus of pesticide, antibiotic, and heavy metal resistance in selected crop and fallow soils having history of consistent pesticide applications. GC-MS analysis estimated residuals of chlorpyrifos, hexachlorbenzene, and dieldrin showing persistent nature of pesticides that pose selective pressure for microbial adaptation. Taxonomic profiling showed increased abundance of pesticide degrading Streptomyces, Xanthomonas, Cupriavidus, and Pseudomonas across the selected soils. Genes encoding for pesticide degrading cytochrome p450, organophosphorus hydrolase, aldehyde dehydrogenase, and oxidase were predominant and positively correlated with Bacillus, Sphingobium, and Burkholderia. Nitrogen-fixing genes (nifH, narB, and nir) were relatively less abundant in crop soils, correlating to the decrease in nitrogen-fixing bacteria (Anabaena, Pantoea, and Azotobacter). Microbial enzymes involved in carbon (pfkA, gap, pgi, and tpiA) and phosphorus cycle (gmbh and phnJ) were significantly higher in crop soils indicating extensive utilization of pesticide residuals as a nutrient source by the indigenous soil microbiota. Additionally, presence of antibiotic and heavy metal resistance genes suggested potential cross-resistance under pressure from pesticide residues. The results implied selective increase in pesticide degrading microbes with decrease in beneficial bacteria that resulted in reduced soil health and fertility. The assessment of agricultural soil microbial profile will provide a framework to develop sustainable agriculture practices to conserve soil health and fertility.
土壤中的残留农药会影响驱动养分循环和土壤肥力的自然微生物群落组成和基因图谱。在本研究中，利用宏基因组学方法来确定在选定的有持续农药施用历史的作物土壤和休耕土壤中，养分循环和微生物组成的变化，以及农药、抗生素和重金属抗性之间的联系。气相色谱 - 质谱联用（GC-MS）分析估计了毒死蜱、六氯苯和狄氏剂的残留量，表明这些农药具有持久性，对微生物适应构成了选择性压力。分类学分析表明，在选定的土壤中，降解农药的链霉菌属、黄单胞菌属、贪铜菌属和假单胞菌属的丰度增加。编码降解农药的细胞色素p450、有机磷水解酶、醛脱氢酶和氧化酶的基因占主导地位，且与芽孢杆菌属、鞘氨醇单胞菌属和伯克霍尔德菌属呈正相关。固氮基因（nifH、narB和nir）在作物土壤中的丰度相对较低，这与固氮细菌（鱼腥藻属、泛菌属和固氮菌属）数量的减少相关。参与碳循环（pfkA、gap、pgi和tpiA）和磷循环（gmbh和phnJ）的微生物酶在作物土壤中显著更高，这表明本地土壤微生物群将农药残留作为养分来源进行了广泛利用。此外，抗生素和重金属抗性基因的存在表明在农药残留的压力下可能存在交叉抗性。结果表明，随着有益细菌数量的减少，降解农药的微生物选择性增加，导致土壤健康和肥力下降。对农业土壤微生物图谱的评估将为制定可持续农业实践以保护土壤健康和肥力提供一个框架。
