What is a Microbial Genome?

A microbial genome is a complete sequence of a given microbe's genetic code. The size of the genome in microbes can vary considerably; the finished size of an organism does not necessarily have a bearing on the size of its genetic code. Microbes have been along for an extremely long time, and as a result, many have very large and complex genomes which carry a great deal of interesting historical and genetic information.

Microbes, also known as microorganisms, are living organisms which are so small that they can only be seen with the assistance of microscopy. Some examples of microbes include green algae, bacteria, protists, archaea, plankton, and some fungi. These organisms vary widely in complexity, from extremely simple living organisms to others which are much more complex. Microbes can be found everywhere, and they have a number of important biological functions, ranging from participating in the breakdown of organic material to carrying agents of disease.

The genome is the complete set of any organism's genetic material. In the case of a microbial genome, it consists of a fully sequenced set of genetic information from a microbe. By fully sequencing the microbial genome, researchers can learn much more about the microbe and what it does. For example, they may be able to trace the evolutionary history of the organism, and to see where it and others diverged from a common ancestor. Likewise, researchers can start to learn more about the specific functions of some DNA sequences, finding out which parts of the genome do what.

With bacteria, sequencing the microbial genome is complicated by the fact that many bacteria carry plasmids. A plasmid is a segment of DNA which is not carried on a chromosome. This extrachromosomal DNA can be exchanged between bacteria, and may sometimes be integrated into the microbial genome, depending on which organism is involved and the environmental pressured it faces. Genome analysis of bacteria can include separate analysis to identify plasmids.

Numerous labs all over the world perform research on microbial genomes. Several governments have set up gene sequencing projects which are designed to advance knowledge of microbial genomes, in part with the goal of developing scientific uses for microorganisms. For example, sequencing of some bacteria has revealed that they could be useful in environmental cleanup, while understanding of how plasmids work has led to the use of genetically engineered plasmids which can be used to insert genetic material into other organisms.