TAXONOMY: cellular organisms -> Bacteria -> Terrabacteria group -> Actinobacteria -> Actinobacteria
'Actinobacteria' is a phylum of Gram-positive bacteria with high guanine and cytosine content in their DNA. The G+C content of Actinobacteria can be as high as 70%, though some may have a low G+C content. They can be terrestrial or aquatic. Although understood primarily as soil bacteria, they might be more abundant in freshwaters. Actinobacteria is one of the dominant bacterial phyla and contains one of the largest of bacterial genera, Streptomyces.C.Michael Hogan. 2010. [http://www.eoearth.org/article/Bacteria?topic=49480 Bacteria. Encyclopedia of Earth. eds. Sidney Draggan and C.J.Cleveland, National Council for Science and the Environment, Washington DC] Analysis of glutamine synthetase sequence has been suggested for phylogenetic analysis of Actinobacteria. Although some of the largest and most complex bacterial cells belong to the Actinobacteria, the group of marine Actinomarinales has been described as possessing the smallest free-living prokaryotic cells.