Crystallizing bacterial extracellular protein reveals paths of silver mineralization for recovery

IF 7.2 2区工程技术 Q1 ENGINEERING, CHEMICAL

Journal of Environmental Chemical Engineering Pub Date : 2025-09-10 DOI:10.1016/j.jece.2025.119215

Fiaz Ahmad , Noreen Ashraf , Xudong Deng, Da-Chuan Yin

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引用次数: 0

Abstract

Heavy metal pollution calls for green recovery strategies. In response to metal stress, bacteria secrete extracellular proteins (ECPs), but the specific role of an individual extracellular protein (ECP) in silver ion (Ag²⁺) mineralization and recovery remains unexplored. Here, we investigated how a single ECP from silver-hypertolerant Enterobacter cloacae mediates Ag²⁺ mineralization. Proteomics (LC-MS/MS, MALDI-TOF) identified the 15.6 kDa protein as an inosine-monophosphate dehydrogenase (ImpD) homolog, whose secretion peaks in medium containing 15.9 ppm Ag²⁺. Partially purified ImpD crystallized at 20–30 °C. Time-resolved in-situ crystallography and X-ray diffraction captured monomers assembling into donut-shaped hexamers that weave into thread-like lattices; these ordered scaffolds template orientation-specific nucleation of Ag-rich crystals, enabling complete silver recovery from aqueous medium in 1.5 h. This previously unrecognized single-protein mediated biomineralization mechanism reveals specific ECPs as programmable bio-lixiviants, offering a low-energy, solvent-free route to metal recovery and expanding the toolkit for biometallurgy and environmental remediation.

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细菌胞外蛋白的结晶揭示了银矿化恢复的途径

重金属污染呼唤绿色恢复战略。在对金属胁迫的反应中，细菌分泌细胞外蛋白（ECP），但单个细胞外蛋白（ECP）在银离子（Ag2+）矿化和恢复中的具体作用尚不清楚。在这里，我们研究了来自银超耐受阴沟肠杆菌的单个ECP如何介导Ag 2 +矿化。蛋白质组学（LC-MS/MS, MALDI-TOF）鉴定15.6 kDa蛋白为肌苷-单磷酸脱氢酶（ImpD）同源物，该蛋白在含有15.9 ppm Ag 2 +的培养基中分泌最多。部分纯化的ImpD在20-30℃下结晶。时间分辨原位晶体学和x射线衍射捕获的单体组装成甜甜圈形状的六聚体，编织成线状晶格；这些有序的支架模板定向成核富银晶体，使银在1.5 h内从水介质中完全回收。这种以前未被认识到的单蛋白介导的生物矿化机制揭示了特定的ECPs作为可编程的生物助剂，为金属回收提供了一种低能量、无溶剂的途径，并扩展了生物冶金和环境修复的工具包。

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来源期刊

Journal of Environmental Chemical Engineering Environmental Science-Pollution

CiteScore

11.40

自引率

6.50%

发文量

2017

审稿时长

27 days

期刊介绍： The Journal of Environmental Chemical Engineering (JECE) serves as a platform for the dissemination of original and innovative research focusing on the advancement of environmentally-friendly, sustainable technologies. JECE emphasizes the transition towards a carbon-neutral circular economy and a self-sufficient bio-based economy. Topics covered include soil, water, wastewater, and air decontamination; pollution monitoring, prevention, and control; advanced analytics, sensors, impact and risk assessment methodologies in environmental chemical engineering; resource recovery (water, nutrients, materials, energy); industrial ecology; valorization of waste streams; waste management (including e-waste); climate-water-energy-food nexus; novel materials for environmental, chemical, and energy applications; sustainability and environmental safety; water digitalization, water data science, and machine learning; process integration and intensification; recent developments in green chemistry for synthesis, catalysis, and energy; and original research on contaminants of emerging concern, persistent chemicals, and priority substances, including microplastics, nanoplastics, nanomaterials, micropollutants, antimicrobial resistance genes, and emerging pathogens (viruses, bacteria, parasites) of environmental significance.