Species diversity in hot spring microbial mats as revealed by both molecular and enrichment culture approaches — relationship between biodiversity and community structure

We have conducted long-term studies of microbial mats of hot springs as model systems for investigating composition and structure of natural microbial communities and as modern analogs of stromatolites (Ward et al. 1984, 1987, 1989b). As recently as the last symposium on microbial mats our knowledge of the biodiversity within these communities was based solely on microbial species cultivated from such mat systems. The view has changed dramatically in the intervening years, because of the application of culture-independent techniques to recover and probe ribosomal RNAs (rRNAs) as biomarkers representing individual mat community members (Ward et al. 1992; Weller et al. 1992 and references cited therein), and more recently because of the renewed attempt to cultivate more relevant species. Here, we summarize what is currently known. The evidence suggests that the molecular methods we are using (Ward et al. 1992) may still not permit a complete understanding of the true complexity of the community. However, the approach does provide insight into understanding the basis behind this large biodiversity and into how more relevant species can be cultivated.