text: Some major bacterial strains identified as being able to ferment lactose are in the genera Escherichia, Citrobacter, Enterobacter and Klebsiella . All four of these groups fall underneath the family of Enterobacteriaceae. These four genera are able to be separated from each other by using biochemical testing, and simple biological tests are readily available. Apart from whole-sequence genomics, common tests include H2S production, motility and citrate use, indole, methyl red and Voges-Proskauer tests.