Patra Mrinmoy, Pandey Anand Kumar, Dubey Suresh Kumar
Molecular Ecology Laboratory, Department of Botany, Institute of Science, Banaras Hindu University, Varanasi, 221005, India.
Department of Biotechnology Engineering, Institute of Engineering and Technology, Bundelkhand University, Jhansi, 284128, India.
World J Microbiol Biotechnol. 2025 Mar 28;41(4):114. doi: 10.1007/s11274-025-04323-9.
The emergence of multidrug-resistant bacteria in agro-environments poses serious risks to public health and ecological balance. In this study, Exiguobacterium sp. E21L, an endophytic strain, was isolated from carrot leaves cultivated in soil amended with sewage treatment plant-derived sludge. The strain exhibited resistance to clinically relevant antibiotics, including beta-lactams, fluoroquinolones, aminoglycosides, and macrolides, with a high Multi-Antibiotic Resistance Index of 0.88. Whole-genome sequencing revealed a genome of 3.06 Mb, encoding 3894 protein-coding genes, including antimicrobial resistance genes (ARGs) such as blaNDM, ermF, tetW, and sul1, along with heavy metal resistance genes (HMRGs) like czcD, copB, and nikA. Genomic islands carrying ARGs and stress-related genes suggested potential horizontal gene transfer. The strain demonstrated robust biofilm formation, high cell hydrophobicity (> 80%), and significant auto-aggregation (90% at 48 h), correlating with genes associated with motility, quorum sensing, and stress adaptation. Notably, phenotypic assays confirmed survival under simulated gastrointestinal conditions, emphasizing its resilience in host-associated environments. Comparative genomics positioned Exiguobacterium sp. E21L near Exiguobacterium chiriqhucha RW-2, with a core genome of 2716 conserved genes. Functional annotations revealed genes involved in xenobiotic degradation, multidrug efflux pumps, and ABC-type transporters, indicating versatile resistance mechanisms and metabolic capabilities. The presence of ARGs, HMRGs, and MGEs (mobile genetic elements) highlights the potential role of Exiguobacterium sp. E21L as a reservoir for resistance determinants in agricultural ecosystems. These findings emphasized the need for stringent regulations on sludge-based fertilizers and advanced sludge treatment strategies to mitigate AMR risks in agro-environments.
农业环境中多重耐药细菌的出现对公众健康和生态平衡构成了严重风险。在本研究中，从用污水处理厂污泥改良土壤中种植的胡萝卜叶中分离出内生菌株嗜麦芽窄食单胞菌E21L。该菌株对临床相关抗生素具有抗性，包括β-内酰胺类、氟喹诺酮类、氨基糖苷类和大环内酯类，多重抗生素抗性指数高达0.88。全基因组测序显示基因组大小为3.06 Mb，编码3894个蛋白质编码基因，包括blaNDM、ermF、tetW和sul1等抗菌抗性基因（ARGs），以及czcD、copB和nikA等重金属抗性基因（HMRGs）。携带ARGs和应激相关基因的基因组岛表明存在潜在的水平基因转移。该菌株表现出强大的生物膜形成能力、高细胞疏水性（>80%）和显著的自聚集性（48小时时为90%），这与与运动性、群体感应和应激适应相关的基因有关。值得注意的是，表型分析证实该菌株在模拟胃肠道条件下能够存活，强调了其在宿主相关环境中的适应性。比较基因组学将嗜麦芽窄食单胞菌E21L定位在嗜麦芽窄食单胞菌Chiriqhucha RW-2附近，核心基因组有2716个保守基因。功能注释揭示了参与外源生物降解、多药外排泵和ABC型转运蛋白的基因，表明其具有多种抗性机制和代谢能力。ARGs、HMRGs和移动遗传元件（MGEs）的存在突出了嗜麦芽窄食单胞菌E21L作为农业生态系统中抗性决定因素储存库的潜在作用。这些发现强调了对基于污泥的肥料实施严格监管以及采用先进污泥处理策略以降低农业环境中抗生素耐药性风险的必要性。
