| description |
Polyploid bacteria are more common than previously believed; however, little is known about the genetic and functional diversity incurred by having multiple chromosomes. We show, using the largest known freshwater bacterium, Achomatium sp., that single cells can host a genetic diversity equal to that of entire populations. No correlation was found between genetic diversity and functional role. The cells contain an excessive number of transposable elements and we hypothesize that these are involved in, intracellular, inter- and intra-chromosome gene re-arrangements; however, the integrity of operons is maintained. We further hypothesize that gene convergence is strongly reduced in these cells as suggested by the high diversity of the usually conserved 16S rRNA gene. Imaging the 16S rRNA distribution inside the cells points to the potentially spatial-differential expression of genes. Thus, intracellular gene transfer (iGT) leads to a large genetic diversity and potentially accelerated evolution. Polyploidy, multiple alleles, and localized gene expression, suggests Achromatium (and perhaps other polyploid bacteria) uses a genetic machinery similar to multicellular eukaryotes. |