Goordial J, Altshuler Ianina, Hindson Katherine, Chan-Yam Kelly, Marcolefas Evangelos, Whyte Lyle G
Department of Natural Resource Sciences, McGill University, Ste. Anne-de-Bellevue, QC, Canada.
Bigelow Laboratory for Ocean Sciences, East Boothbay, ME, United States.
Front Microbiol. 2017 Dec 20;8:2594. doi: 10.3389/fmicb.2017.02594. eCollection 2017.
Significant progress is being made in the development of the next generation of low cost life detection instrumentation with much smaller size, mass and energy requirements. Here, we describe life detection and sequencing in the field in soils over laying ice wedges in polygonal permafrost terrain on Axel Heiberg Island, located in the Canadian high Arctic (79°26'N), an analog to the polygonal permafrost terrain observed on Mars. The life detection methods used here include (1) the cryo-iPlate for culturing microorganisms using diffusion of in situ nutrients into semi-solid media (2) a Microbial Activity Microassay (MAM) plate (BIOLOG Ecoplate) for detecting viable extant microorganisms through a colourimetric assay, and (3) the Oxford Nanopore MinION for nucleic acid detection and sequencing of environmental samples and the products of MAM plate and cryo-iPlate. We obtained 39 microbial isolates using the cryo-iPlate, which included several putatively novel strains based on the 16S rRNA gene, including a sp. (96% closest similarity in GenBank) which we partially genome sequenced using the MinION. The MAM plate successfully identified an active community capable of L-serine metabolism, which was used for metagenomic sequencing with the MinION to identify the active and enriched community. A metagenome on environmental ice wedge soil samples was completed, with base calling and uplink/downlink carried out via satellite internet. Validation of MinION sequencing using the Illumina MiSeq platform was consistent with the results obtained with the MinION. The instrumentation and technology utilized here is pre-existing, low cost, low mass, low volume, and offers the prospect of equipping micro-rovers and micro-penetrators with aggressive astrobiological capabilities. Since potentially habitable astrobiology targets have been identified (RSLs on Mars, near subsurface water ice on Mars, the plumes and oceans of Europa and Enceladus), future astrobiology missions will certainly target these areas and there is a need for direct life detection instrumentation.
下一代低成本生命探测仪器的开发正在取得重大进展，其尺寸、质量和能源需求都要小得多。在此，我们描述了在位于加拿大北极地区（北纬79°26'）的阿克塞尔·海伯格岛上多边形永久冻土区域覆盖冰楔的土壤中进行的野外生命探测和测序，该区域可类比火星上观测到的多边形永久冻土区域。这里使用的生命探测方法包括：（1）低温培养板，利用原位养分扩散到半固体培养基中来培养微生物；（2）微生物活性微量分析（MAM）板（BIOLOG生态板），通过比色法检测现存的活微生物；（3）牛津纳米孔MinION，用于环境样本以及MAM板和低温培养板产物的核酸检测和测序。我们使用低温培养板获得了39株微生物分离株，基于16S rRNA基因，其中包括几种推测为新的菌株，包括一种 菌属（在GenBank中相似度最高为96%），我们使用MinION对其进行了部分基因组测序。MAM板成功鉴定出一个能够进行L-丝氨酸代谢的活跃群落，该群落被用于与MinION进行宏基因组测序，以鉴定活跃且富集的群落。完成了环境冰楔土壤样本的宏基因组测序，通过卫星互联网进行碱基识别和上行/下行传输。使用Illumina MiSeq平台对MinION测序进行验证，结果与MinION获得的结果一致。这里使用的仪器和技术是现有的，成本低、质量轻、体积小，并有望为微型漫游车和微型穿透器配备强大的天体生物学探测能力。由于已经确定了潜在的宜居天体生物学目标（火星上的季节性斜坡纹线、火星近地表的水冰、木卫二和土卫二的羽流和海洋），未来的天体生物学任务肯定会针对这些区域，因此需要直接的生命探测仪器。
