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Ebook Prescott's microbiology (9th edition): Part 2

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(BQ) Part 2 book "Prescott's microbiology" presentation of content: The diversity of the microbial world, ecology and symbiosis, pathogenicity and host response, microbial diseases, detection, and their control, applied microbiology,.and other contents. | Microbial Taxonomy and the Evolution of Diversity There are more microbes on Earth than stars in the universe. This vast diversity reflects the roughly 3.5 billion years in which microbes have evolved to adapt to seemingly every environment on (and in) the planet, regardless of how inhospitable it may seem to a plant or animal. Scientists Query: "Is the Microbial Universe Expanding?" well as some viruses, so there were plenty of known sequences for comparison. Over 4,600 recA and 1,800 rpoB genes were analyzed and subdivided into groups of protein subfamilies. Amazingly, members of one subfamily for each protein were found to be completely unrelated to T he more you know, the more you discover. Evolutionary biologist Dr. Jonathan Eisen wanted to discover as much as possible from the any other known protein on Earth. So, is this evidence of a new domain? Perhaps. Alternatively, these sequences could be ancient relatives of the genomic sequences of previously unknown bacteria and archaea. more familiar proteins, or they could be from some unusual viruses. But if However, he realized that the genome database was limited to the they do represent a new domain, we would add to Bacteria, Archaea, and genomes of microbes already chosen for sequencing because they were the Eukarya the . well, it's too early to choose a name. But time, and pathogenic, industrially relevant, or had some other desired trait. So his more scientific discovery, will tell. research group, in collaboration with the Joint Genome Institute, set out In this chapter, we explore microbial taxonomy and evolution-how to diversify the database by sequencing bacterial and archaeal genomes and why microorganisms are classified using an evolutionary framework. across the evolutionary spectrum. When computers were used to This was not always the case, and the move to an evolution-based system translate the nucleotide sequences into their protein and RNA products, resulted in the reclassification of