This taxon was revived in 2006 by Cavalier-Smith as an infrakindgom containing the phyla Spirochaetae, Sphingobacteria, Planctobacteria, and Proteobacteria.
Este taxon que estaba sendo abandonado foi revivido en 2006 por Cavalier-Smith, que o considerou un infrarreino que contiña os filos Spirochaetae, Sphingobacteria, Planctobacteria, e Proteobacteria.