Bacteria are some of the simplest forms of life and have been studied by scientists trying to identify the smallest collection of genes ?or minimal genome ?that is needed for maintaining life.
Traditionally scientists have done this by removing, or 'knocking out', a series of individual genes from a bacterial genome to see what effect this has on its ability to survive.
They can then infer which genes are essential to the organism, and which are not, to work out which are needed for the minimal genome.
However this knock out approach wrongly removes many of the genes that are essential to the survival of bacteria, according to researchers from Heidelberg (Germany), Manchester (UK), Budapest (Hungary) and Bath (UK).
The researchers made this discovery after developing a new approach to genome modelling which, given the organism's evolutionary history and knowledge of its surrounding environment, allows them to predict which genes a bacterium's genome should contain.
"Previous attempts to work out the minimal genome have relied on deleting individual genes in order to infer which genes are essential for maintaining life," said Professor Laurence Hurst from the Department of Biology and Biochemistry at the University of Bath.
"This knock out approach misses the fact that there are alternative genetic routes, or pathways, to the production of the same cellular product.
"When you knock out one gene, the genome can compensate by using an alternative gene.
"But when you repeat the knock out experiment by deleting the alternative, the genome can revert to the original gene instead.
"Using the knock-out approach you could infer that both genes are expendable from the genome because there appears to be no deleterious effect in both experim
Source:University of Bath