Fossils of bacteria dating back 3.5 billion years have been discovered. There are over 5,000 different species of bacteria known, many of which are harmful or pathogenic (i.e. can cause disease) and some of which are beneficial and can have many uses, for example the bacterial species Lactobacillus is used in the production of cheese and yoghurt. The bacterium Bifidobacterium teenagers is used for the production of yogurt and Brevibacterium aurantiacum is used for the production of cheese. Yeast is also used in the production of beers and spirits such as wine and also plays a role in the leavening of bread. In addition to bacteria used for food production, there are also many types of bacteria used in the production of medicines with almost a different bacterium used for each different contractable disease in humans, for example the bacterium Moraxella lacunta is used to produce medicines for conjunctivitis and Klebsiellapneumoniae would be used to make medicines for pneumonia. In order for bacteria to be used to their full potential and meet the quantity requirements necessary for the production of food and medicines, it is essential that experts are able to distinguish firstly which type of bacteria is necessary for a given production and secondly place, and very importantly, how to reproduce the bacteria to create a sufficient quantity for the mass production of a certain product. All living things must reproduce as it is necessary to pass on genes to offspring to ensure the survival of the species and prevent its spread. . Natural selection is the main mechanism of the evolution of species. It chooses which traits are more favorable adaptations for the environment in which the species lives and which are unfavorable. Individuals of the species will end up being bread and butter ...... of bacterial DNA and viruses. When they invade the bacterial cell they use the bacterial protein machinery to produce virions. During the packaging process in which genetic material is inserted into the newly formed virus, fragments of bacterial DNA are also included. The new virions carry the bacterial DNA into the next cell they infect. Transforming bacteria are able to absorb foreign DNA through their cell membranes. This foreign DNA most often remains as an extrachromosomal structure called a plasmid. It can integrate into the bacterial genome. conjunction or sexual reproduction between bacteria containing an F plasmid (F+) and one without the plasmid (F-). A temporary structure called a conjugation tube forms between the two interacting bacteria and exchange of genetic material occurs http://wiki.answers.com/Q/What_are_3_ways_genetic_recombination_occurs_in_meiosis#slide=1