Ionescu Danny, Bizic-Ionescu Mina, De Maio Nicola, Cypionka Heribert, Grossart Hans-Peter
Leibniz Institute of Freshwater Ecology and Inland Fisheries, Department of Experimental Limnology, Alte Fischerhuette 2, 16775, Stechlin, Germany.
Institute for Emerging Infections, Oxford Martin School, University of Oxford, 34 Broad Street, Oxford, OX1 3BD, UK.
Nat Commun. 2017 Sep 6;8(1):455. doi: 10.1038/s41467-017-00342-9.
Polyploid bacteria are common, but the genetic and functional diversity resulting from polyploidy is unknown. Here we use single-cell genomics, metagenomics, single-cell amplicon sequencing, and fluorescence in situ hybridization, to show that individual cells of Achromatium oxaliferum, the world's biggest known freshwater bacterium, harbor genetic diversity typical of whole bacterial communities. The cells contain tens of transposable elements, which likely cause the unprecedented diversity that we observe in the sequence and synteny of genes. Given the high within-cell diversity of the usually conserved 16S ribosomal RNA gene, we suggest that gene conversion occurs in multiple, separated genomic hotspots. The ribosomal RNA distribution inside the cells hints to spatially differential gene expression. We also suggest that intracellular gene transfer may lead to extensive gene reshuffling and increased diversity.The cells of Achromatium bacteria are remarkably large and contain multiple chromosome copies. Here, Ionescu et al. show that chromosome copies within individual cells display high diversity, similar to that of bacterial communities, and contain tens of transposable elements.
多倍体细菌很常见，但多倍体所产生的遗传和功能多样性尚不清楚。在这里，我们使用单细胞基因组学、宏基因组学、单细胞扩增子测序和荧光原位杂交技术，来证明世界上已知最大的淡水细菌草酸无色菌的单个细胞具有整个细菌群落典型的遗传多样性。这些细胞含有数十个转座元件，这可能导致了我们在基因序列和共线性中观察到的前所未有的多样性。鉴于通常保守的16S核糖体RNA基因在细胞内具有高度多样性，我们认为基因转换发生在多个分离的基因组热点区域。细胞内核糖体RNA的分布暗示了空间差异基因表达。我们还认为细胞内基因转移可能导致广泛的基因重排和增加的多样性。草酸无色菌的细胞非常大，并且包含多个染色体拷贝。在这里，约内斯库等人表明，单个细胞内的染色体拷贝表现出高度多样性，类似于细菌群落的多样性，并且包含数十个转座元件。
