Galbraith P, Henry R, McCarthy D T
Environmental and Public Health Microbiology Laboratory (EPHM Lab), Monash Water for Liveability, Department of Civil Engineering, Monash University, Wellington Road, Clayton, Victoria 3800 Australia.
J Biol Eng. 2019 Jun 6;13:52. doi: 10.1186/s13036-019-0175-2. eCollection 2019.
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 ( ser. Typhimurium and ).
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 ( < 0.0001). (median MIC: 8 mg/mL; range: [4-16 mg/mL]) (16 mg/mL, [2-16 mg/mL]) and (8 mg/mL, [4-16 mg/mL]) exhibited the strongest inhibitory activity against the selected bacteria ( < 0.05 compared to each tested non-myrtaceous candidate). In contrast, the Australian biofilter gold standard demonstrated eight-fold lower activity than the highest performer (64 mg/mL, [32-64 mg/mL]).
Our results suggest that myrtaceous plants, particularly , 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.
生物滤池是基于土壤-植物的被动雨水处理系统，在去除粪便微生物方面表现出了一定的潜力，尽管效果并不稳定。产抗菌物质的植物是一种安全、廉价但研究不足的生物滤池设计组成部分，可能会提高处理的可靠性。生物滤池中植物介导的微生物去除的潜在机制尚未完全阐明，特别是在抗菌物质产生方面。因此，本研究的目的是通过对适合生物滤池的植物物种进行抗菌筛选，为优化病原体处理的生物滤池植被选择指南提供依据。这包括：（1）在维多利亚州（澳大利亚东南部）的背景下选择适合生物滤池的本土植物（17种）；（2）对选定植物的甲醇提取物（每个物种≥5个生物学重复；共86个）针对参考雨水粪便细菌（鼠伤寒沙门氏菌血清型和）进行抗菌药敏试验。
本研究是关于多种受试物种极性醇提取物抑制活性的首次报告。以产生抗菌油而闻名的桃金娘科植物提取物的最低抑菌浓度（MIC）明显低于非桃金娘科植物候选物（<0.0001）。（中位MIC：8mg/mL；范围：[4 - 16mg/mL]）（16mg/mL，[2 - 16mg/mL]）和（8mg/mL，[4 - 16mg/mL]）对选定细菌表现出最强的抑制活性（与每个受试非桃金娘科候选物相比，P<0.05）。相比之下，澳大利亚生物滤池的黄金标准植物的活性比表现最佳的植物低八倍（64mg/mL，[32 - 64mg/mL]）。
我们的结果表明，桃金娘科植物，特别是，在介导抗菌作用从而改善生物滤池内病原体处理方面可能比目前的植被黄金标准更有效。建议在生物滤池环境中对这些植物进行进一步研究，以完善生物滤池植被选择指南。
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