really universal in the Bacteria?
As with any “rule” of biology, as more and more data becomes available, exceptions occur. To date, several species of Mycoplasma (capricolum, mobile, mycoides, pulmonis, and synoviae) and Ureaplasma parvum have been found to lack type I chaperonin genes as well as other genes previously considered essential for prokaryotic life. All of these organisms are obligate intracellular species. Interestingly, eight species of Mycoplasma and Candidatus Carsonella ruddii, which has the smallest genome recognized to date (~160 kb), do have a type I chaperonin genes.
