Marcolefas Evangelos, Leung Tiffany, Okshevsky Mira, McKay Geoffrey, Hignett Emma, Hamel Jérémie, Aguirre Gabriela, Blenner-Hassett Olivia, Boyle Brian, Lévesque Roger C, Nguyen Dao, Gruenheid Samantha, Whyte Lyle
Department of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, Canada.
Department of Microbiology and Immunology, McGill University, Montreal, QC, Canada.
Front Microbiol. 2019 Aug 9;10:1836. doi: 10.3389/fmicb.2019.01836. eCollection 2019.
The goal of this study was to isolate, screen, and characterize Arctic microbial isolates from Expedition Fjord, Axel Heiberg Island, Nunavut, Canada capable of inhibiting the growth of foodborne and clinically relevant pathogens. Arctic bacteria were isolated from twelve different high Arctic habitats pertaining to active layer permafrost soil, saline spring sediments, lake sediments, and endoliths. This was achieved using (1) the cryo-iPlate, an innovative cultivation device within active layer permafrost soil and (2) bulk plating of Arctic samples by undergraduate students that applied standard culturing methods. To mitigate the possibility of identifying isolates with already-known antibacterial activities, a cell-based dereplication platform was used. Ten out of the twelve Arctic habitats tested were found to yield cold-adapted isolates with antibacterial activity. Eight cold-adapted Arctic isolates were identified with the ability to inhibit the entire dereplication platform, suggesting the possibility of new mechanisms of action. Two promising isolates, initially cultured from perennial saline spring sediments and from active layer permafrost soil ( sp. GHS.8.NWYW.5 and sp. AALPS.10.MNAAK.13, respectively), displayed antibacterial activity against foodborne and clinically relevant pathogens. sp. GHS.8.NWYW.5 was capable of inhibiting methicillin resistant and susceptible (MRSA and MSSA), , and O157:H7. sp. AALPS.10.MNAAK.13 was observed to have antagonistic activity against MRSA, MSSA, , , and . After whole genome sequencing and mining, the genome of sp. GHS.8.NWYW.5 was found to contain seven putative secondary metabolite biosynthetic gene clusters that displayed low homology (<50% coverage, <30% identity, and e-values > 0) to clusters identified within the genome of the type strain pertaining to the same species. These findings suggest that cold-adapted Arctic microbes may be a promising source of novel secondary metabolites for potential use in both industrial and medical settings.
本研究的目标是从加拿大努纳武特地区阿克塞尔·海伯格岛探险峡湾中分离、筛选并鉴定能够抑制食源性病原体和临床相关病原体生长的北极微生物菌株。北极细菌是从与活动层永久冻土土壤、盐泉沉积物、湖泊沉积物和石内微生物相关的十二个不同的高北极栖息地中分离出来的。这是通过以下方式实现的：（1）使用cryo-iPlate，这是一种用于活动层永久冻土土壤中的创新培养装置；（2）由本科生采用标准培养方法对北极样本进行批量平板接种。为了降低鉴定具有已知抗菌活性的菌株的可能性，使用了基于细胞的去重复平台。在所测试的十二个北极栖息地中，有十个被发现产生了具有抗菌活性的冷适应菌株。鉴定出八个具有抑制整个去重复平台能力的冷适应北极菌株，这表明存在新的作用机制的可能性。两个有前景的菌株，最初分别从多年生盐泉沉积物和活动层永久冻土土壤中培养出来（分别为GHS.8.NWYW.5菌株和AALPS.10.MNAAK.13菌株），对食源性病原体和临床相关病原体表现出抗菌活性。GHS.8.NWYW.5菌株能够抑制耐甲氧西林和敏感的金黄色葡萄球菌（MRSA和MSSA）、大肠杆菌和O157:H7。观察到AALPS.10.MNAAK.13菌株对MRSA、MSSA、大肠杆菌、肺炎克雷伯菌和鲍曼不动杆菌具有拮抗活性。经过全基因组测序和挖掘，发现GHS.8.NWYW.5菌株的基因组包含七个推定的次生代谢物生物合成基因簇，这些基因簇与同一物种模式菌株基因组中鉴定出的基因簇显示出低同源性（覆盖率<50%、同一性<30%且e值>0）。这些发现表明，冷适应的北极微生物可能是工业和医学领域潜在使用的新型次生代谢物的一个有前景的来源。
