Bacteria

Actinobacteria

History and taxonomy

The first bacteria were observed by Antony van Leeuwenhoek in 1683 using a single-lens microscope of his own design. The name bacterium was introduced much later, by Ehrenberg in 1828, derived from the Greek word βακτηριον meaning "small stick". Louis Pasteur (1822-1895) and Robert Koch (1843-1910) described the role of bacteria as conveyors and causes of disease or pathogens.

Related Topics:
Antony van Leeuwenhoek - 1683 - Ehrenberg - 1828 - Greek word - Louis Pasteur - Robert Koch - Pathogen

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Originally the bacteria were considered microscopic fungi (called Schizomycetes), except for the photosynthetic cyanobacteria, which were considered a group of algae (called Cyanophyta or blue-green algae). It was only with the study of detailed cell structure that it was realized they formed a fundamental group, separate from the other organisms. In 1956 Copeland gave them their own kingdom Mychota, later renamed Monera, Prokaryota, or Bacteria. During the 1960s the concept was refined and bacteria (now including cyanobacteria) were recognized as one of two major divisions of the living world, together with the eukaryotes. Eukaryotes were generally believed to have evolved from bacteria, later from assemblies of bacteria.

Related Topics:
Fungi - Cyanobacteria - Algae - Blue-green algae - Eukaryotes - Evolved

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The advent of molecular systematics challenged this view. In 1977, Woese divided the prokaryotes into two groups based on 16S rRNA sequences, called the kingdoms Eubacteria and Archaebacteria. He argued that each of these and the eukaryotes all evolved separately and in 1990 emphasized this by promoting them to domains, which were renamed the Bacteria, Archaea, and Eucarya. This redefinition has generally been accepted by molecular biologists but criticized by some others, who maintain that he over-emphasized a few genetic differences and that both archaebacteria and eukaryotes probably developed from within the eubacteria.

Related Topics:
Molecular systematics - Woese - RRNA - Archaebacteria - Domains - Archaea - Eucarya

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Single gene sequencing for systematics has led to whole genome sequencing, currently 239 bacterial genomes have been completed with 498 partially completed http://www.ncbi.nlm.nih.gov/genomes/lproks.cgi.

Related Topics:
Sequencing - Genome sequencing - Genome

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