A new Tree of Life; getting bushier (Evolution)

by David Turell , Monday, June 15, 2015, 18:27 (3448 days ago) @ David Turell

New studies find more types of bacteria and Archaea:-http://phys.org/news/2015-06-newfound-groups-bacteria-tree-life.html-
"University of California, Berkeley, scientists have identified more than 35 new groups of bacteria, clarifying a mysterious branch of the tree of life that has been hazy because these microbes can't be reared and studied in the lab.
 
"The new groups make up more than 15 percent of all known groups or phyla of bacteria, the scientists say, and include the smallest life forms on Earth, microbes a mere 400 nanometers across. The number of new bacterial phyla is equal to all the known animal phyla on Earth.-"The scientists, who recently also identified nine new groups of microbes known as Archaea, see these new additions to life on Earth as a sign that the accepted tree of life - a division into the three domains of eukaryotes, which includes animals and plants, bacteria and Archaea - needs to be revised.-"All life is divided into three domains, though everything we see around us is from only one of them: the eukaryotes, or organisms that have nuclei in their cells. Within the eukaryotes there are about 35 animal phyla - the phylum Chordata includes humans and all other vertebrates - 12 plant phyla and a few fungi. The microscopic bacterial domain has been much fuzzier because some organisms detected widely in the environment fail to grow in culture like other bacteria.-"By some estimates there are 100 bacterial phyla, though only 29 have representatives that will grow in culture. The new discovery allowed the team not only to define about a third of all bacterial phyla but, thanks to the nearly complete genomes, to characterize their lifestyles.-"'People have seen these bacteria in surveys of many different environments all over the planet, so we've known that they are there, and that they are fairly ubiquitous," Brown said. "What we didn't know is what the organisms were and what they were capable of doing."-"About half of all the genes in these 35-plus phyla are new and unlike other known genes. The recognizable genes suggest that most of the bacteria use a simple process of fermentation to make the energy they need, instead of using aerobic or anaerobic respiration like many other bacteria. They also have unusual ribosomes, the multi-protein machines that translate genetic instructions into proteins. In fact, routine genomic scans would not detect them because of their distinctive 16S ribosomal RNA genes. The UC Berkeley team found that some of the bacteria have very rare inserts, called introns, in genes coding for 16S ribosomal RNA, which make them invisible to current detection techniques.-"'We found that all of these have at least a couple of unusual ribosomal features, and many are missing ribosomal proteins that are thought to be either universal across the tree of life or in all of bacteria," Banfield said.-"'The unusual ribosomes, the small genomes - between 600 and 1,100 genes - the inability to synthesize amino acids and nucleotides, and a consistent metabolic story really connects these bacteria together in a pretty surprising way," Brown said."