Before revision:  Noteworthy, a phase transition is observed such that, for  k\ge40, bacterial PPI network are mostly populated by genes that are conserved, essential and which, in most cases, belong to the COG J, a category of genes which is related to ribosomal functions and to the processing of genetic information.
After revision:  Noteworthy, a phase transition is observed such that, for k\ge40, bacterial PPI networks are mostly populated by genes that are conserved, essential and which, in most cases, belong to the COG J, a category of genes which is related to ribosomal functions and to the processing of genetic information.