The dynamics of bacterial genome has aroused from a long series of evolutionary events. These evolutionary events are responsible for unique set of biological function in large number of bacteria. Bacteria have two separate genetic systems such as chromosomal DNA and extra-chromosomal DNA. Both genetic systems can undergo gene transfer by various means which accelerates process of evolution in bacterial community. Genetic diversity led by evolution is main cause of bacterial adoptability to vast range of conditions. Bacteria are present everywhere even at extreme conditions such as high salinity, extremely high and low temperature where no higher animal will survive. They have different phenotypic characters along with diverse metabolic activity. There are many processes involved in bacterial genomic diversity such as mutation, recombination and Horizontal gene transfer.
Mutations are natural alteration during DNA replication or it may occur due to a mutagen. Recombination most commonly takes place between closely related bacterial strains and its frequency decreases with decreasing sequence similarity between the donor and recipient. While mutation brings variation in existing genome, recombination serves alteration within a species. But both of them has little contribution for microbial evolution in comparison to the horizontal gene transfer which alters the genes across the species boundaries.
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