Before revision:  Noteworthy, a structural transition in the network is observed such that, for connectivities k\ge40 , bacterial PPI networks are mostly populated by genesthat are conserved, essential and which , in most cases, belong to the COG cluster J, related to ribosomal functions and to the processing of genetic information.
After revision:  Noteworthy, a structural transition in the network is observed such that, for connectivities k\ge40 ), which is ubiquitous among the species considered here -- though mostly visible in the degree distributions of bacteria with small genomes (less than 1000 genes). The genes that belong to this highly connected core are conserved, essential and which , in most cases, belong to the COG cluster J, related to ribosomal functions and to the processing of genetic information.