Michael Evans, St. Mary's College of Maryland

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Abstract:

We offer a quantitative synthesis of current research on in situ microbial community diversity. The lack of explicit quantitative statements on phylogenetic distribution, and the recent exponential climb in the application of 16S rRNA gene probes to natural systems prompted our research. In this review, studies in several natural systems, both broad and remote, were examined from some leading journals, including Applied and Environmental Microbiology, and FEMS Microbiology. Studies utilizing molecular techniques, such as polymerase chain reaction amplification (PCR) or fluorescence in situ hybridization (FISH), were synthesized according to the reported percentages of rRNA contribution by phylogenetic clades to the total community rRNA amount. Distinct shifts in community profile were observed across marine, freshwater, sediment, soil, and some extreme systems. Moreover, comparison of Eubacteria staining success observed a systematic variance in resolution across these natural systems. This observation, when taken with the small, unbalanced collection of in situ studies, suggests a need for further research to refine our understanding of the extent and function of microbial diversity.