Microbial genetics

Microbial genetics is a subject area within microbiology and genetic engineering. It studies the genetics of very small (micro) organisms; bacteria, archaea, viruses and some protozoa and fungi. This involves the study of the genotype of microbial species and also the expression system in the form of phenotypes.

Since the discovery of microorganisms by two Fellows of The Royal Society, Robert Hooke and Antoni van Leeuwenhoek during the period 1665-1885 they have been used to study many processes and have had applications in various areas of study in genetics. For example: Microorganisms' rapid growth rates and short generation times are used by scientists to study evolution. Microbial genetics also has applications in being able to study processes and pathways that are similar to those found in humans such as drug metabolism.

Bacteria have been on this planet for approximately 3.5 billion years, and are classified by their shape.Bacterial genetics studies the mechanisms of their heritable information, their chromosomes, plasmids, transposons, and phages.

Gene transfer systems that have been extensively studied in bacteria include genetic transformation, conjugation and transduction. Natural transformation is a bacterial adaptation for DNA transfer between two cells through the intervening medium. The uptake of donor DNA and its recombinational incorporation into the recipient chromosome depends on the expression of numerous bacterial genes whose products direct this process. In general, transformation is a complex, energy-requiring developmental process that appears to be an adaptation for repairing DNA damage.

Bacterial conjugation is the transfer of genetic material between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells. Bacterial conjugation has been extensively studied in Escherichia coli, but also occurs in other bacteria such as Mycobacterium smegmatis. Conjugation requires stable and extended contact between a donor and a recipient strain, is DNase resistant, and the transferred DNA is incorporated into the recipient chromosome by homologous recombination. E. coli conjugation is mediated by expression of plasmid genes, whereas mycobacterial conjugation is mediated by genes on the bacterial chromosome.

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