Millard Kylah B, Unuofin John O, Invernizzi Luke, Daramola Michael O, Iwarere Samuel A
Sustainable Energy and Environment Research Group (SEERG), Department of Chemical Engineering, Faculty of Engineering, Built Environment and Information Technology (EBIT), University of Pretoria, Pretoria, South Africa.
Biodiscovery Centre, Department of Chemistry, Faculty of Natural and Agricultural Sciences (NAS), University of Pretoria, Pretoria, South Africa.
Environ Microbiol Rep. 2025 Oct;17(5):e70182. doi: 10.1111/1758-2229.70182.
This study investigated the antimicrobial potential of rhizospheric microbiota isolated from heavy-metal-contaminated soils against two extremely drug-resistant (XDR) pathogens, Pseudomonas aeruginosa (strain ATCC 27853) and Acinetobacter baumannii (strain ATCC-BAA-1605). Heavy-metal-contaminated rhizospheres were sequentially exposed to ex-situ and in vitro enrichment with heavy metals from battery waste and incubated for 168 h. The surviving microbiota were screened against P. aeruginosa and A. baumannii, and crude extracts of high-performing strains were tested against the pathogens using agar well diffusion assays. The novelty and components of the extracted secondary metabolites from environmentally stressed rhizospheric microorganisms were inferred using ultra-performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS). Results indicated that these secretions inhibited the growth of XDR pathogens (approximately 3.0 × 10 CFU/mL), forming inhibition zones of up to 50 mm. Furthermore, the pathogens were more responsive to exudates from microbiota in environmentally stressed rhizospheres compared to those from organic rhizospheres (control). Heavy-metal-stressed microbiota secrete metabolites that show superior antimicrobial activity and successfully inhibit the growth of XDR pathogens. The UPLC-HRMS analysis indicated the tentative characterisation of the metabolites, particularly Tolyposamine and Gentiatibetine, by the evaluated microbiota, suggesting their relevance as biopharmaceuticals, and could lead to future antibiotic production.
本研究调查了从重金属污染土壤中分离出的根际微生物群对两种极耐药（XDR）病原体——铜绿假单胞菌（菌株ATCC 27853）和鲍曼不动杆菌（菌株ATCC-BAA-1605）的抗菌潜力。将重金属污染的根际依次进行异地和体外富集，加入电池废料中的重金属，并培养168小时。针对铜绿假单胞菌和鲍曼不动杆菌对存活的微生物群进行筛选，并使用琼脂孔扩散试验对高性能菌株的粗提物针对病原体进行测试。使用超高效液相色谱-高分辨率质谱（UPLC-HRMS）推断来自环境胁迫根际微生物的提取次生代谢产物的新颖性和成分。结果表明，这些分泌物抑制了XDR病原体的生长（约3.0×10 CFU/mL），形成了高达50毫米的抑菌圈。此外，与来自有机根际（对照）的分泌物相比，病原体对环境胁迫根际中微生物群的分泌物反应更敏感。重金属胁迫的微生物群分泌的代谢产物具有优异的抗菌活性，并成功抑制了XDR病原体的生长。UPLC-HRMS分析表明，经评估的微生物群初步鉴定了这些代谢产物，特别是托利波胺和龙胆替丁，表明它们作为生物药物的相关性，并可能导致未来抗生素的生产。
