The Classification of Prokaryotes

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9306171 Woese In renewed studies on bacteria, Dr. Carl Woese of University of Illinois continues investigations of the evolution, phylogeny, and classification of microbes through the analysis of genomic sequence data from ribosomal RNA in order to quantify genetic differences between groups of bacteria. By comparing the sequence of ribosomal RNA from a variety of organisms, a branching pattern of genealogical affinity can be constructed with the use of computer analyses of the hundreds and thousands of nucleotide bases involved. Few nucleotide differences between taxa indicate close evolutionary relationship (the sharing of similar genomes from a close common ancestor) whereas greater mutational differences indicate more ancient divergence between lineages. Three groups are targeted for study this time: purple photosynthetic bacteria; certain neglected groups of Gram positive bacteria; and cytophaga, flexibacter, and bacteroides subgroups. %%% An additional benefit of the phylogenetic analysis of bacteria is the ability to design diagnostic molecular "fingerprinting" probes, that can be used in ecological and medical studies to identify unknown bacteria. Also, the phylogenetic relationships revealed through comparative nucleotide sequence analyses provide an evolutionary framework for studying other aspects of microbial physiology, biochemistry, and ecology.