metagenomics is the study of genetic material recovered directly from the environment samples. This broad field of microbiology differs from the traditional where the genomic sequencing mainly depent on the clonal culture. here the large microbial groups which are not easy to culture in a lab are studied in their enviromental conditons. This term was used in a publication in 1998 by Jo Handelsman et. al., University of Wisonsin, Department of Plant Pathology. This term is also knows, environmental genomics, ecogenomics, or community genomics.Metagenomic studies of seawater and feces have revealed thousands of previously unknown viruses and bacteria. Marine sediment was found to have millions of previously unknown viruses.The National Institutes of Health is considering a project to sequence all of the microbes of the human body. Currently only 1% of the bodies microbes can be sequenced. A microbe genome is one thousand times shorter than the human genome. However, there are a lot of different microbes that need to be sequenced.
Early environmental gene sequencing cloned specific genes (often the 16S rRNA gene) to produce a profile of diversity in a natural sample. Such work revealed that the vast majority of microbial biodiversity had been missed by cultivation-based methods. Recent studies use "shotgun" Sanger sequencing or massively parallel pyrosequencing to get (mostly) unbiased samples of all genes from all members of sampled communities.
Metagenomics has many applications. Metagenomic knowledge helps us to understand the biological processes that effect human health and agriculture. Metagenomics has been used to find new antibiotics and can be used for other advancements in medicine.
It can also be used to enable superior industrial processes such as the efficient creation of biofuels. Biofuels could help us solve our energy problems related to increasing oil prices and to the environmental impact of fossil fuels.
It is well known that the vast majority of microbes have not been cultivated. Functional metagenomics strategies are being used to explore the interactions between plants and microbes through cultivation-independent study of the microbial communities.