BACKGROUND Biofilters are soil-plant based passive stormwater treatment systems which demonstrate promising, although inconsistent, removal of faecal microorganisms. Antimicrobial-producing plants represent a safe, inexpensive yet under-researched biofilter design component that may enhance treatment reliability. The mechanisms underlying plant-mediated microbial removal in biofilters have not been fully elucidated, particularly with respect to antimicrobial production. The aim of this study was therefore to inform biofilter vegetation selection guidelines for optimal pathogen treatment by conducting antimicrobial screening of biofilter-suitable plant species. This involved: (1) selecting native plants suitable for biofilters (17 species) in a Victorian context (southeast Australia); and (2) conducting antimicrobial susceptibility testing of selected plant methanolic extracts (≥ 5 biological replicates/species; 86 total) against reference stormwater faecal bacteria (Salmonella enterica subsp. enterica ser. Typhimurium, Enterococcus faecalis and Escherichia coli). RESULTS The present study represents the first report on the inhibitory activity of polar alcoholic extracts from multiple tested species. Extracts of plants in the Myrtaceae family, reputed for their production of antimicrobial oils, demonstrated significantly lower minimum inhibitory concentrations (MICs) than non-myrtaceous candidates (p < 0.0001). Melaleuca fulgens (median MIC: 8 mg/mL; range: [4-16 mg/mL]), Callistemon viminalis (16 mg/mL, [2-16 mg/mL]) and Leptospermum lanigerum (8 mg/mL, [4-16 mg/mL]) exhibited the strongest inhibitory activity against the selected bacteria (p < 0.05 compared to each tested non-myrtaceous candidate). In contrast, the Australian biofilter gold standard Carex appressa demonstrated eight-fold lower activity than the highest performer M. fulgens (64 mg/mL, [32-64 mg/mL]). CONCLUSION Our results suggest that myrtaceous plants, particularly M. fulgens, may be more effective than the current vegetation gold standard in mediating antibiosis and thus improving pathogen treatment within biofilters. Further investigation of these plants in biofilter contexts is recommended to refine biofilter vegetation selection guidelines.

中文翻译：

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杀手植物的崛起：研究澳大利亚植物的抗菌活性以增强生物过滤器介导的病原体去除。

背景技术生物过滤器是基于土壤植物的被动雨水处理系统，其证明了有希望但不一致地去除粪便微生物。生产抗菌素的植物代表了一种安全、廉价但研究不足的生物过滤器设计组件，可以提高处理的可靠性。生物过滤器中植物介导的微生物去除的机制尚未完全阐明，特别是在抗菌素生产方面。因此，本研究的目的是通过对适合生物过滤器的植物物种进行抗菌筛选，为生物过滤器植被选择指南提供最佳病原体处理信息。这包括：（1）在维多利亚时代（澳大利亚东南部）选择适合生物过滤器的原生植物（17 种）；(2) 对选定的植物甲醇提取物（≥ 5 个生物复制/物种；总共 86 个）针对参考雨水粪便细菌（沙门氏菌肠炎亚种肠鼠伤寒、粪肠球菌和大肠杆菌）进行抗菌敏感性测试。结果 本研究首次报告了来自多个测试物种的极性酒精提取物的抑制活性。桃金娘科植物提取物以生产抗菌油而闻名，其最低抑菌浓度 (MICs) 显着低于非桃金娘科候选植物 (p < 0.0001)。Melaleuca fulgens（中位 MIC：8 mg/mL；范围：[4-16 mg/mL]）、Callistemon viminalis（16 mg/mL，[2-16 mg/mL]）和 Leptospermum lanigerum（8 mg/mL，[4-16 mg/mL]）对选定的细菌表现出最强的抑制活性（与每个测试的非桃金娘属候选菌相比，p < 0.05）。相比之下，澳大利亚生物过滤器黄金标准 Carex appressa 的活性比表现最高的 M. fulgens (64 mg/mL, [32-64 mg/mL]) 低 8 倍。结论 我们的研究结果表明，桃金娘科植物，特别是 M. fulgens，可能比目前的植被金标准更有效地介导抗菌作用，从而改善生物过滤器内的病原体处理。建议在生物过滤器环境中对这些植物进行进一步调查，以完善生物过滤器植被选择指南。澳大利亚生物过滤器黄金标准 Carex appressa 的活性比表现最好的 M. fulgens (64 mg/mL, [32-64 mg/mL]) 低 8 倍。结论 我们的研究结果表明，桃金娘科植物，特别是 M. fulgens，可能比目前的植被金标准更有效地介导抗菌作用，从而改善生物过滤器内的病原体处理。建议在生物过滤器环境中对这些植物进行进一步调查，以完善生物过滤器植被选择指南。澳大利亚生物过滤器黄金标准 Carex appressa 的活性比表现最好的 M. fulgens (64 mg/mL, [32-64 mg/mL]) 低 8 倍。结论 我们的研究结果表明，桃金娘科植物，特别是 M. fulgens，可能比目前的植被金标准更有效地介导抗菌作用，从而改善生物过滤器内的病原体处理。建议在生物过滤器环境中对这些植物进行进一步调查，以完善生物过滤器植被选择指南。