Metagenomics is the culture-independent analysis of genomes of microbial communities<xref ref-type="bibr" rid="bib001">1</xref>. This field has come up with many exciting revelations that directly find applications in industry and therapeutics. Thus, what began with exploring the microbial diversity of uncultivable bacteria has already grown into a fullfledged field, geared up to harness the potential of microbial diversity in full swing. The diversity of Sargasso Sea<xref ref-type="bibr" rid="bib002">2</xref> and the discovery of new antibiotics<xref ref-type="bibr" rid="bib003">3</xref> and genes<xref ref-type="bibr" rid="bib004">4</xref> from varied environments are some of the significant contributions of metagenomics. Recent investigations of gut microbes that form a part of the “metagenome” of human/mouse model have created a stir in the scientific community as it bears direct consequences on public health<xref ref-type="bibr" rid="bib005">5</xref>,<xref ref-type="bibr" rid="bib006">6</xref>. In its December 21, 2006, issue, the science journal <italic>Nature</italic> (Vol. 444) published an article that further highlighted the potential of metagenomics. In the study led by Prof. Jeffrey Gordon of Washington University, St. Louis, USA, the researchers explored the microflora in the gut of mice models using metagenomic approach to find if any correlation could be drawn between the microflora and obese and lean subjects<xref ref-type="bibr" rid="bib005">5</xref>,<xref ref-type="bibr" rid="bib006">6</xref>. The study depicted that the microbial population inhabiting the gastrointestinal tract of both humans and mice belongs to two groups, the firmicutes and the bacteroidetes. They further found that the proportion of firmicutes is greater in obese people and mice, than in lean subjects. Interestingly, their study reveals that it is just not our brain, body fat and our body metabolism that is involved in the energy balance equation but also these bacteria that are present in the gut. To substantiate the results, microbes from obese mice were transferred to the gut of lean germ-free mice; the latter gained twice as much fat in nearly two weeks compared to their lean counterparts. They discovered that gut bacteria in obese mice were more efficient than those in lean mice at harvesting calories from complex, indigestible dietary polysaccharides found in fruits, vegetables and grains and depositing these (calories) in fat. Though the mechanism responsible for mediating linkage between relative abundance of bacteroidetes to firmicutes and adiposity in both mice and humans is yet to be studied, this study demonstrates the possibility and utility of applying comparative metagenomics in understanding the complex nature of interactions between humans and microbial communities. On the applied side, if one selectively allows either of the two bacterial groups to flourish in the gut microflora, it may help one to either gain or loose weight.</sec></body><back><ref-list><title>References

IJM

Indian Journal of Microbiology

0046-8991

The Association of Microbiologists of India

ijm-46-4-017

RESEARCH ARTICLE

Metagenomics: You are what your bacteria eat!

Lal

Rup

*Sharma

Pooja

Kumari

Hansi

Kumar

Mukesh

Kumari

Kirti

Gupta

Sanjay Kumar

Malhotra

Shweta

Kumari

Rekha

Department of Zoology, University of Delhi, Delhi-110007.

*E-mail: ijmami@gmail.com, Tel: 91 11 27666254.

122006

464414414

Metagenomics is the culture-independent analysis of genomes of microbial communities<xref ref-type="bibr" rid="bib001">1</xref>. This field has come up with many exciting revelations that directly find applications in industry and therapeutics. Thus, what began with exploring the microbial diversity of uncultivable bacteria has already grown into a fullfledged field, geared up to harness the potential of microbial diversity in full swing. The diversity of Sargasso Sea<xref ref-type="bibr" rid="bib002">2</xref> and the discovery of new antibiotics<xref ref-type="bibr" rid="bib003">3</xref> and genes<xref ref-type="bibr" rid="bib004">4</xref> from varied environments are some of the significant contributions of metagenomics. Recent investigations of gut microbes that form a part of the “metagenome” of human/mouse model have created a stir in the scientific community as it bears direct consequences on public health<xref ref-type="bibr" rid="bib005">5</xref>,<xref ref-type="bibr" rid="bib006">6</xref>. In its December 21, 2006, issue, the science journal <italic>Nature</italic> (Vol. 444) published an article that further highlighted the potential of metagenomics. In the study led by Prof. Jeffrey Gordon of Washington University, St. Louis, USA, the researchers explored the microflora in the gut of mice models using metagenomic approach to find if any correlation could be drawn between the microflora and obese and lean subjects<xref ref-type="bibr" rid="bib005">5</xref>,<xref ref-type="bibr" rid="bib006">6</xref>. The study depicted that the microbial population inhabiting the gastrointestinal tract of both humans and mice belongs to two groups, the firmicutes and the bacteroidetes. They further found that the proportion of firmicutes is greater in obese people and mice, than in lean subjects. Interestingly, their study reveals that it is just not our brain, body fat and our body metabolism that is involved in the energy balance equation but also these bacteria that are present in the gut. To substantiate the results, microbes from obese mice were transferred to the gut of lean germ-free mice; the latter gained twice as much fat in nearly two weeks compared to their lean counterparts. They discovered that gut bacteria in obese mice were more efficient than those in lean mice at harvesting calories from complex, indigestible dietary polysaccharides found in fruits, vegetables and grains and depositing these (calories) in fat. Though the mechanism responsible for mediating linkage between relative abundance of bacteroidetes to firmicutes and adiposity in both mice and humans is yet to be studied, this study demonstrates the possibility and utility of applying comparative metagenomics in understanding the complex nature of interactions between humans and microbial communities. On the applied side, if one selectively allows either of the two bacterial groups to flourish in the gut microflora, it may help one to either gain or loose weight.</sec></body><back><ref-list><title>References1Handelsman

(2004). Metagenomics: Application of genomics to uncultured microorganisms. Microbiol Mol Biol Revs, 68: 699–685.2Venter

Remington

Heidelberg

Halpern

Rusch

Eisen

Paulsen

Nelson

Fouts

Levy

Knap

Lomas

Nealson

White

Peterson

Hoffman

Parsons

Baden-Tillson

Pfannkoch

Rogers

Smith

(2004). Environmental genome shotgun sequencing of the Sargasso Sea. Science, 304: 66–74.3Gillespie

Brady

Bettermann

Cianciotto

Liles

Rondon

Clardy

Goodman

Handelsman

(2002). Isolation of Antibiotics Turbomycin A and B from a Metagenomic Library of Soil Microbial DNA. Appl. Environ Microbiol, 68: 4301–4306.4Yun

Kang

Park

Yoon

Kim

M-J

Heu

Ryu

(2004). Characterization of a Novel Amylolytic Enzyme Encoded by a Gene from a Soil-Derived Metagenomic Library. Appl Environ Microbiol, 70: 7229–7235.5Turnbaugh

Ley

Mahowald

Magrini

Mardis

Gordon

(2006). An obesity-associated gut microbiome with increased capacity for energy harvest. Nature. 444: 1027–1031.6Ley

Turnbaugh

Klein

Gordon

(2006). Human gut microbes associated with obesity. Nature, 444: 1022–1023.