Microbial genetics is a subject area within microbiology and genetic engineering. Microbial genetics studies microorganisms for different purposes. The microorganisms that are observed are bacteria and archaea. Some fungi and protozoa are also subjects used to study in this field. The studies of microorganisms involve studies of genotype and expression system. Genotypes are the inherited compositions of an organism. (Austin, "Genotype," n.d.) Genetic Engineering is a field of work and study within microbial genetics. The usage of recombinant DNA technology is a process of this work. The process involves creating recombinant DNA molecules through manipulating a DNA sequence. That DNA created is then in contact with a host organism. Cloning is also an example of genetic engineering.

Since the discovery of microorganisms by 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. Robert Hooke and Antoni van Leeuwenhoek discoveries involved depictions, observations, and descriptions of microorganisms. Mucor is the microfungus that Hooke presented and gave a depiction of. His contribution being, Mucor as the first microorganism to be illustrated. Antoni van Leeuwenhoek's contribution to the microscopic protozoa and microscopic bacteria yielded to scientific observations and descriptions. These contributions were accomplished by a simple microscope, which led to the understanding of microbes today and continues to progress scientists understanding.   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.

Microbial genetics can focus on Charles Darwin's work and scientists have continued to study his work and theories by the use of microbes. Specifically, Darwin's theory of natural selection is a source used. Studying evolution by using microbial genetics involves scientists looking at evolutionary balance. An example of how they may accomplish this is studying natural selection or drift of microbes. Application of this knowledge comes from looking for the presence or absence in a variety of different ways. The ways include identifying certain pathways, genes, and functions. Once the subject is observed, scientist may compare it to a sequence of a conserved gene. The process of studying microbial evolution in this way lacks the ability to give a time scale of when the evolution took place. However, by testing evolution in this way, scientist can learn the rates and outcomes of evolution. Studying the relationship between microbes and the environment is a key component to microbial genetics evolution.

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.

Transduction is the process by which foreign DNA is introduced into a cell by a virus or viral vector. Transduction is a common tool used by molecular biologists to stably introduce a foreign gene into a host cell's genome.

Archaea is a domain of organisms that are prokaryotic, single-celled, and are thought to have developed 4 billion years ago. "They have no cell nucleus or any other organelles inside their cells."Archaea replicate asexually in a process known as binary fission. The cell division cycle includes when chromosomes of daughter cells replicate. Because archea have a singular structure chromosome, the two daughter cells separate and cell divides. Archaea have motility include with flagella, which is a tail like structure. Archaeal chromosomes replicate from different origins of replication, producing two haploid daughter cells. " They share a common ancestor with bacteria, but are more closely related to eukaryotes in comparison to bacteria. Some Archaea are able to survive extreme environments, which leads to many applications in the field of genetics. One of such applications is the use of archaeal enzymes, which would be better able to survive harsh conditions in vitro.