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BEIJING, July 27 (Xinhuanet) -- Yellowstone National Park's hot springs are famous among scientists as habitats for all sorts of colorful little critters, and the latest to be discovered is a new type of bacteria with light-harvesting antennae. The bacteria, Candidatus Chloracidobacterium (Cab.) thermophilum, belong to the Acidobacteria phylum, which until now was not known to include any chlorophyll-producers. The addition means that six of 25 bacteria phyla now contain light-harvesting members capable of photosynthesis. The finding is detailed in the July 27 issue of the journal Science. "Finding a previously unknown, chlorophyll-producing microbe is the discovery of a lifetime for someone who has studied bacterial photosynthesis for as long as I have (35 years)," said lead study author Don Bryant of Penn State University. Bryant and his colleagues found the bacteria in three hot springs in Yellowstone ˘w Mushroom Spring, Octopus Spring and Green Finger Pool˘w which are located not far from the Old Faithful Geyser. The microbes live near the surface of bacterial mats, where light and oxygen are plentiful. Temperatures there soar from 122 to 151 degrees Fahrenheit (50 to 66 degrees Celsius). The scientists sequenced DNA from the cells of the bacteria, focusing on two genes, one a crucial component of the protein-making machinery and the other a gene essential for converting light energy into chemical energy. The bacteria sport light-harvesting antennae called chlorosomes, which each contain about 250,000 pigments. Until now, the chlorophyll-packed structures haven't been found in any aerobic, or oxygen-tolerant, microbes. The team found the bacterium makes two types of chlorophyll, explaining how it can thrive alongside other species in microbial mats and compete for light with cyanobacteria. (Agencies)
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