B.subtilis

Defining the complete set of genes required for life offers revealing insights into cell physiology. In the Early Edition of the Proceedings of the National Academy of Sciences, Kobayashi and colleagues estimate the number of essential genes in Bacillus subtilis at just 271 (PNAS, DOI:10.1073/pnas.0730515100, March 31, 2003).

B. subtilis is one of the best studied Gram-positive bacteria and its genome encodes around 4100 genes. Computational analysis and systematic gene inactivation experiments were combined to identify the 271 essential genes. Around half of these genes are involved in DNA or RNA metabolism and protein synthesis. One fifth of the genes were assigned to roles in the synthesis of the cell envelope, and regulation of cell shape or division, with a further ten percent needed for energy provision. Eleven of the essential genes (4%) are of unknown function.

As one might expect, the essential genes are highly conserved (over 80%) in ...