268

17

Genomics

indeed the human gastrointestinal tract; cf. Chap. 19). It may sometimes be necessary

to clone the DNA (using cultured laboratory bacteria) in order to produce sufficient

material for further analysis.

The most basic analysis is simply to sequence all the DNA. This may result

in millions of genes, which can be compared with known sequences; early work

appeared to reveal an astonishing diversity of whole classes of hitherto unknown

genes. One should, however, be mindful of the influence of sequencing errors in

giving the appearance of more novelty than is actually the case. ³⁰

Function-based metagenomics obviates the need to sequence the DNA by letting

the fragments be translated, again in laboratory-cultured bacteria. Novel proteins of

phenotypes are then further analysed.

Metagenomics can be used to better understand the diversity and functions of

microbial communities in a wide range of habitats, and to gain insights into the

evolutionary processes that shape the communities. It can also be used to detect and

control potentially disease-causing organisms, and explore the potential of microbial

communities for producing substances useful to mankind.

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