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Life in a different time frame Paulina Tamez Hidalgo, PhD student And so life began Early life 3.5-3.8 billion years ago •Unicellular organisms Photosynthetic bacteria arose prior to 2.8 billion years •Shaping Earth’s atmosphere Despite the great variety of animals and plants that have populated the Earth •Microbes are the dominant life forms present throughout almost all our planet’s After all these years… 1. Bacteria have colonized every known environment 2. They have developed an extremely wide variety of metabolic types Source of energy Sunlight Source of carbon Organic compounds Organic compound s Photoheterotrop Chemoheterotrop hy hy (photosynthetic (Enterobacteria) bacteria) CO2 Photoautotroph y (purple nonsulfur bacteria) Inorganic compounds Lithoheterotrop hy (Iron bacteria) Chemoautotrophy Lithoautotrophy (methanogens) (acetogens) 3. They evolved in various shapes and sizes Coccoid and rodshaped (Streptococcus and Bacillus) Comma’s form (Vibrio cholerae) Club shaped (Clostridium botulinum) Filamentous (Anabaena) Helical form (Helicobacter pylori) Spirochaete (Treponema pallidum) 4. They have not changed dramatically as have been demonstrated by studying ancient bacteria isolated from Abdominal tissue of bees trapped in amber 25 to 40 million years old (Cano and Borucki, 1995) Inside a salt crystal 250 million years old (Vreeland et al., 2000) Ancient glacial ice 750,000 years old (Christner et al., 2003) Why they remain for so long? Certain type of bacteria (Firmicutes), wide-spread form “endospores” Dormant form to which bacteria can reduce itself Not a reproductive structure Remain dormant for long periods of time When the conditions are favorable, can reactivate itself to a vegetative cell (active stage) Endospores of Bacillus subtilis Inside an Endospore : mix of proteins, amino polysaccharides and lipids : a complex protein shell, contains enzymes that are involved in germination : a thick layer of peptidoglycan : a relatively dry compartment that houses the spore, dipicolinic acid, and small acid-soluble proteins : DNA Sensitive to its surroundings. It has the ability to react to the reintroduction small amounts of nutrients that results in the almost immediate conversion of dormant back to an actively growing cell Dormancy as strategy to survive For years, was thought that the deep sub-seabed (high-pressure, minimal oxygen and low supply of nutrients and energy) was an uninhabitable environments In the late 80’s microbial cells were discovered in sediment cores Since then, our knowledge about this deep biosphere has expanded There is a log-log linear decrease with depth Higher in the surface sediment and relatively lower at several hundred meters below (where the sediment has been deposited many million years ago) Barker, (2012) Living microbes were buried thousand to millions years ago How do they remain active? a) Consuming nutrients at a very slow rate The slowly growing bacteria are important for the global storage of organic carbon and thereby for the oxygen content of the atmosphere Different sampling sites at the Peru margin Lomstein et al. (2012) b) Forming endospores Vegetative cells X Mur-based measurements DPA-based measurements Endospores are also abundant in the terrestrial environment Ammann et al. (2011) Uncertain the ratio of vegetative cells versus endospores cells Little is still known regarding the factors controlling their abundance and distribution in soil and sediments The link between environmental conditions, biogeochemical zonation, and endospore abundance is poorly known measurements on: Total organic carbon (TOC) and total nitrogen (TN) Amino acids Amino sugars Dipicolinic acid Cell counts Dormancy as strategy to live the long life Questions?