2. INTRODUCTION
Metagenomics is the study of metagenomes, genetic
material recovered directly from environmental samples.
The term "metagenomics" was first used by Jo
Handelsman, Jon Clardy, Robert M. Goodman, and first
appeared in publication in 1998.
This relatively new field of genetic research enables studies
of organisms that are not easily cultured in a laboratory as
well as studies of organisms in their natural environment.
3. The broad field may also be referred to as
environmental genomics, ecogenomics or community
genomics.
The term metagenome referenced the idea that a
collection of genes sequenced from the environment
could be analyzed in a way analogous to the study of a
single genome.
The human microbiome project (HMP) will require
metagenomic sample sequencing data as a primary
resource for analysis of the relationship between
microbial communities and the individuals they inhabit.
4. Metagenomic approaches
• 3 broad types of metagenomic approaches are:
– Biochemical approach
– Whole genome shotgun (WGS) methods• WGS approaches have been used mainly in environmental
studies from various sites (e.g., sea water, abandoned mines).
– 16s-RNA sequencing (ribotyping)
• Most widely studied approach for microbiological point of
view.
5. Methodological Advances
Natural samples contain DNA in Natural samples
contain DNA in several forms like free DNA, virus
particles, cells, etc.
These samples can be suspended in water, bound to the
soil or other solid particles, or contained within an
aggregate of microorganisms (biofilm).
Now the above 3 approaches can be used.
9. Shotgun sequencing
WGS
sequencing
is
performed by sequencing
the ends of clone libraries
created as small plasmids or
occasionally cosmids. The
individual sequences are
compared
to
sequence
databases to identify
species and genes.
10. Applications
• Metagenomics can improve strategies for monitoring
the impact of pollutants on ecosystems and for
cleaning up contaminated environments. Increased
understanding of bioaugmentation or biostimulation
trials to succeed.
• Recent progress in mining the rich genetic resource of
non-culturable microbes has led to the discovery of
new genes, enzymes, and natural products. The impact
of metagenomics is witnessed in the development of
commodity and fine chemicals, agrochemicals and
pharmaceuticals where the benefit of enzymecatalyzed chiral synthesis is increasingly recognized.
11. • Metagenomic sequencing is being used to
characterize the microbial communities. This is part
of the Human Microbiome initiative with primary
goals to determine if there is a core human
microbiome, to understand the changes in the
human microbiome that can be correlated with
human health, and to develop new technological
and bioinformatics tools to support these goals.
• 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 cultivationindependent study of the microbial communities.
12. Future Directions
• New enzymes, antibiotics, and other reagents
identified
• More exotic habitats can be intently studied
• Can only progress as library technology
progresses, including sequencing technology
• Improved bioinformatics will quicken analysis for
library profiling.
13. • Investigating
ancient
DNA remnants
• Discoveries such as
phylogenic tags (rRNA
genes, etc) will give
momentum to the
growing field
• Learning
novel
pathways will lead to
knowledge about the
current nonculturable
bacteria to then culture
these systems
Culture these
organism
Information
on why
certain
microbes are
uncultured
Discover
novel
pathways
14.
15. References
• Presentation by Susannah Green, Tringe and
Edward M. Rubin - Department of Energy Joint
Genome Institute
• Metagenomics-Current Innovations and Future
Trends: Diana Marco
• www.genomviron.com
• www.Rothamsted.ac.uk
