Metagenoms

Articles

• Kurokawa
• Gill
• JGI
• HMP Nature Oct 2007
• Human Gut Microbiome Initiative (HGMI)

 * Need for more RefSeqs; sequence the genomes of 100 cultured representatives of the phylogenetic diversity in the human gut microbiota

• Nature Reviews: Microbiology in the post-genomic era

Web sites

• JGI FAMeS
• JGI SIMHC
• Human Microbiome Project @ NIH
• WUSTL HGMI 41 genomes

HMP

NIH Roadmap

1. Sequence the genomes of 200 microbes that have been isolated from the human body;
2. Recruit a set of healthy donors and obtain samples from a set of body regions
3. Perform initial 16S rDNA gene metagenomic sequence analyses to estimate the complexity of the microbiota at these sites.

Centers: Baylor, Broad, JCVI, WUSTL

• ~10times more bateria cells than human cells in the body
• small-subunit (16S) ribosomal RNA gene-sequence-based surveys:

 * found in all microorganisms 
 * has enough sequence conservation for accurate alignment 
 * has enough variation for phylogenetic analyses.

• skin, mouth, oesophagus, stomach, colon and vagina
• largest reported data sets are for the gut
• most of the 10–100 trillion microorganisms in the human gastrointestinal tract live in the colon.
• more than 90% of all phylogenetic types (phylotypes) of colonic bacteria belong to just 2 of the 70 known divisions (phyla) in the domain Bacteria: the Firmicutes and the Bacteroidetes.

Firmicutes (Gram-positive bacteria) : 639 Genome Sequences

   * Bacilli    472
   * Clostridia    106
   * Erysipelotrichi    1
   * Mollicutes    60
   * Thermolithobacteria   
   * unclassified Firmicutes sensu stricto   
   * environmental samples    

Bacteroidetes : 53 Genome Sequences

   * Bacteroidetes (class)    22
   * Flavobacteria    21
   * Sphingobacteria    8
   * unclassified Bacteroidetes    1
   * environmental samples    1

Actinobacteria

• In colon, the differences between individuals are greater than the differences between different sampling sites in one individuall
• Comunirties are usually stable over time