Diverse uncultivated ultra-small bacterial cells in groundwater

作者：Luef Birgit; Frischkorn Kyle R; Wrighton Kelly C; Holman Hoi Ying N; Birarda Giovanni; Thomas Brian C; Singh Andrea; Williams Kenneth H; Siegerist Cristina E; Tringe Susannah G; Downing Kenneth H; Comolli Luis R^*; Banfield Jillian F

来源：Nature Communications, 2015, 6(1): 6372.

DOI：10.1038/ncomms7372

Bacteria from phyla lacking cultivated representatives are widespread in natural systems and some have very small genomes. Here we test the hypothesis that these cells are small and thus might be enriched by filtration for coupled genomic and ultrastructural characterization. Metagenomic analysis of groundwater that passed through a similar to 0.2-mu m filter reveals a wide diversity of bacteria from the WWE3, OP11 and OD1 candidate phyla. Cryogenic transmission electron microscopy demonstrates that, despite morphological variation, cells consistently have small cell size (0.009 +/- 0.002 mu m(3)). Ultrastructural features potentially related to cell and genome size minimization include tightly packed spirals inferred to be DNA, few densely packed ribosomes and a variety of pili-like structures that might enable inter-organism interactions that compensate for biosynthetic capacities inferred to be missing from genomic data. The results suggest that extremely small cell size is associated with these relatively common, yet little known organisms.

• 出版日期2015-2