Scientific understanding arises from our observations on nature and its systems which create curiosity to learn from nature. Evolution is the unifying principle for comprehending all life on earth and application of mechanisms for a change that can contribute to human welfare.

The genetic material in an organism makes up its genome. We can collect DNA from an entire community of microbes of various species in a particular location to obtain metagenome. It is possible now to isolate DNA fragments, determine the fragments sequences and reassemble then into contiguous sequences instead of culturing each species in lab and isolate DNA fragment which is highly labour intensive.

Ecosystems are dynamic complexes of plant animal and microbial communities and the non-living environment interacting as fundamental units. Every living system has ecosystems namely intestinal system, reproductive system etc where microbes do exist and interact.

The metagenomic analysis of microbes in human intestinal tract revealed more than 100 times as many difference genes as are found in our genome, (which contain 25000 genes) and about 300 previously unknown unculturable microbial life forms.

It is well known that microbes and their genes play a significant role in the development of our immune system, in the fatty acid production (that powers intestinal growth). Detoxification of ingested substances that could otherwise lead to cancers cell growth or alter our ability to metabolize medicine by the microbial communities is well documented. Metagenomic analysis suggest that changes in the occurrence, abundance and interaction of both known and unknown microbes play in human diseases such as inflammatory bowel diseases or obesity ,

Similar metagenomic analysis of reproductive tract in female revealed that bacterial vaginosis, a disease associated with premature labour and delivery, pelvic inflammatory disease and the acquisition of sexually transmitted pathogen like HIV is accompanied by dramatic change in the species, composition of viginal bacterial communities. The healthy and unhealthy viganal ecosystem reveals many new bacterial groups. Hence treatment of bacterial viganosis requires further identification of appropriate microbes.

Metagenomic analysis can also be used to study the external ecosystems like water samples from oceans to determine biological diversity which we have not fully understood as the microbial communities are responsible for the supply of life on the earth including photosynthesis by making the necessary carbon, oxygen and sulphur accessible to the other life forms. Hence we have to study the microbial metagenomes and evolutionary ecology to know the sustainability of microbes over time in evolution. What drives microbes to maintain ecosystem is an important task.

Microbes produce and consume carbon-dioxide and methane and other green house gases that can be play an active role in containing global warming. Thus an intensive study has to concentrated to identify the appropriate microbes to prevent global warming.

Metagenomics can diagnose environmentally health problems, detection of disease in humans and livestock. Newly discovered microbes can be used to develop new antibiotics and new enzymes to convert cellulose into glucose as well as bioremediation of soil water where we are facing acute problems on ecological sustainability and environmental integrity.