3 Genomic inventory of permafrost microorganisms

The genomic inventory of a permafrost soil can be obtained through genomic characterization of the whole community (metagenomics) and/or an organism isolated from permafrost through culture or single-cell based methods. While there is often debate among the scientific community over whether genomic, transcriptomic, proteomic, or culture-based methods are best, the most promising current work combines knowledge from multiple culture-dependent and culture-independent approaches in comparative analyses of different permafrost and active-layer soils and nearby or related ecosystems. Because high-throughput shotgun methods of genomics and proteomics are relatively recent (and not always financially accessible to research groups), most work done on permafrost communities has utilized phylogenetic surveys based on small sub-unit (SSU) rRNA and functional gene (e.g. mcrA, pmoA) surveys to characterize cryotic soil communities. In less than a decade, our knowledge of permafrost and cryosol communities has shifted from piece-meal to the beginnings of a holistic understanding.