Prokaryotes are divided into two distinct groups: the bacteria and the archaea ... is contained in a central area of the cell called the nucleoid, which is not surrounded by a nuclear membrane.

Planctomycetes challenge our concept of the bacterial cell and of a prokaryote as a cell structure type, as well as our ideas about origins of the eukaryote nucleus. Planctomycetes Are Important ...

Aggressins alone, separated from bacteria and exudate cells by filtration ... data that virulence is a multiple biological ...