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Anoxygenic photosynthetic communities and heavy element transformations in extreme environments: hydrothermal and hypersaline ecosystems

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dc.contributor.supervisor Yurkov, Vladimir (Microbiology) en
dc.contributor.author Csotonyi, Julius Thomas
dc.date.accessioned 2011-01-20T15:05:51Z
dc.date.available 2011-01-20T15:05:51Z
dc.date.issued 2011-01-20T15:05:51Z
dc.identifier.citation Csotonyi, Julius T.,; Stackebrandt, Erko; and Yurkov, Vladimir. (2006). Anaerobic respiration on tellurate and other metalloids in bacteria from hydrothermal vent fields in the Eastern Pacific Ocean. Applied and Environmental Microbiology 72:4950-4956. en
dc.identifier.citation Csotonyi, Julius T.; Swiderski, Jolantha; Stackebrandt, Erko; and Yurkov, Vladimir. (2008). Novel halophilic aerobic anoxygenic phototrophs from a Canadian hypersaline spring system. Extremophiles 12:529–539. en
dc.identifier.uri http://hdl.handle.net/1993/4387
dc.description.abstract The current research project investigated the anoxygenic phototrophic and metal(loid) transforming bacteria of hypersaline and deep ocean hydrothermal environments. The East German Creek brine springs, an unusual flowing hypersaline system, was enumerated using classical techniques. Subterranean sulfide supported purple sulfur and nonsulfur bacteria, but at the highly oxygenated surface, aerobic anoxygenic phototrophs (AAP) were numerically dominant (up to 16-36% of cultivable bacteria). Strains (EG8, EG13, EG17, EG19) with unusual phylogenetic affiliation and novel photosynthetic and metal(loid) reducing traits were described taxonomically. Chromocurvus halotolerans gen. nov., sp. nov. was proposed as a second example of a gammaproteobacterial AAP. It exhibited bent rod-shaped cells, unusual among AAP. Facultatively anaerobic Charonomicrobium ambiphototrophicum gen. nov., sp. nov. was capable of both aerobic and anaerobic anoxygenic photosynthesis, and incapable of photoautotrophy, distinguishing it from both AAP and purple nonsulfur bacteria. Roseovarius vanadiphilum sp. nov. surprisingly produced 4.5 times more biomass and 2 times more bacteriochlorophyll (BChl) at extremely high NaVO3 concentration (7.5 g/l) than in metal-free medium. A second novel metabolic mode, anaerobic respiration on the toxic metalloid tellurate, was described for a relative of non-phototrophic Shewanella frigidimarina (ER-Te-48), from deep ocean hydrothermal vent Paralvinella worms at Explorer Ridge in the Pacific Ocean. Other strains respired on SeO32- (ER-Se-17L), VO3- (ER-V-6), and VO43- (AV-V-25). These organisms provided the first examples of anaerobic respiration on Te, Se and V at hydrothermal vents. High level resistance of AAP to metal(loid)s prompted investigation of the influence of TeO32- on photosynthetic pigment production in species including Erythromicrobium ramosum (from a terrestrial hydrothermal system) and Erythrobacter litoralis (from a hypersaline supralittoral system). Tellurite enhanced photosynthetic pigment production up to 3.4 times, consistent with an antioxidant carotenoid-based defense mechanism. However, in E. litoralis BChl precursors such as Mg protoporphyrin or its monomethyl ester also accumulated, indicating biosynthetic pathway interruption. In hydrothermal and hypersaline ecosystems, largely devoid of eukaryotic phototrophs but often enriched in metal(loid)s, AAP and metal(loid) reducers are key modulators of nutrient and toxin availability. The presented results on their ecology, physiology and biochemistry have important implications for theoretical understanding of extreme environments and hold potential for biotechnological applications. en
dc.format.extent 5843997 bytes
dc.format.mimetype application/pdf
dc.language.iso en_US
dc.rights info:eu-repo/semantics/openAccess
dc.subject extreme environments en
dc.subject aerobic anoxygenic phototrophs en
dc.subject microbial photosynthesis en
dc.subject bacteriochlorophyll en
dc.subject carotenoids en
dc.subject microbial ecology en
dc.subject hypersaline springs en
dc.subject hydrothermal vents en
dc.subject tellurium en
dc.subject microbial metal reduction en
dc.subject bioremediation en
dc.subject microbial mats en
dc.subject purple nonsulfur bacteria en
dc.subject selenite en
dc.subject metavanadate en
dc.subject Roseovarius en
dc.subject tellurite en
dc.subject metalloids en
dc.title Anoxygenic photosynthetic communities and heavy element transformations in extreme environments: hydrothermal and hypersaline ecosystems en
dc.type info:eu-repo/semantics/doctoralThesis
dc.degree.discipline Microbiology en
dc.contributor.examiningcommittee Worobec, Elizabeth (Microbiology) Markham, John (Biological Sciences) Mas, Jordi (Universitat Autònoma de Barcelona) en
dc.degree.level Doctor of Philosophy (Ph.D.) en
dc.description.note February 2011 en


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