Molecular-phylogenetic analyses of human gastrointestinal microbiota

Molecular-phylogenetic methods have revolutionized the analysis of complex microbial communities. Polymerase chain reaction amplification and phylogen etic analysis of small-subunit ribosomal RNA gene sequences allow microbes to be identified objectively, even in the absence of cultivation. Furthermore, the sequence information obtained by these means can be used t o design sequence-based tools for identifying, tracking, and diagnosing the presence of microbes in complex samples. In this article, we summarize thi s approach and review its application to the study of the human gastrointes tinal microbiota. Although just beginning, molecular-phylogenetic surveys o f human gut microbes have revealed that most microbes identified in the gas trointestinal tract represent novel, previously undescribed species. A full description of the microbial constituents of the human gut will set the gr oundwork for interpreting how the gastrointestinal microbiota influence the health of the host. (C) 2001 Lippincott Williams & Wilkins, Inc.