It is also possible to color code human disease genes and these maps are available. The newest twist to this method is to color code genes identified in gene chip arrays as being expressed in the same manner. These may be genes in a single pathway or genes involved in the same process. Gaps in pathways can be identified, and predictions made about an organism's metabolic strategies. Essential pathways present in microorganisms but absent in humans are of course targets for antimicrobial drugs.
Obvious examples are the vitamin biosynthetic pathways in bacteria.
Currently, the KEGG has analyzed 36 complete genomes and also includes partial data on humans and other important species whose whole genomes are not yet sequenced. They cover 39 species. You should try looking at some of the maps that are hyperlinked in the text below. It may be interesting to compare yeast with E. coli and Methanococcus jannaschii to get a feeling for similarities and differences between the three main domains of life Archaea, Bacteria and Eukarya. Clicking on an enzyme box will link you to the information on that gene, including the enzyme name the protein sequence and the nucleotide sequence.