| Coassimilation of organic substrates via the autotrophic 3-hydroxypropionate bi-cycle in Chloroflexus aurantiacus. | |
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MedLine Citation:
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PMID: 21764971 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Chloroflexus aurantiacus is a facultative autotrophic green nonsulfur bacterium that grows phototrophically in thermal springs and forms microbial mats with cyanobacteria. Cyanobacteria produce glycolate during the day (photorespiration) and excrete fermentation products at night. C. aurantiacus uses the 3-hydroxypropionate bi-cycle for autotrophic carbon fixation. This pathway was thought to be also suited for the coassimilation of various organic substrates such as glycolate, acetate, propionate, 3-hydroxypropionate, lactate, butyrate, or succinate. To test this possibility, we added these compounds at a 5 mM concentration to autotrophically pregrown cells. Although the provided amounts of H(2) and CO(2) allowed continuing photoautotrophic growth, cells immediately consumed most substrates at rates equaling the rate of autotrophic carbon fixation. Using [(14)C]acetate, half of the labeled organic carbon was incorporated into cell mass. Our data suggest that C. aurantiacus uses the 3-hydroxypropionate bi-cycle, together with the glyoxylate cycle, to channel organic substrates into the central carbon metabolism. Enzyme activities of the 3-hydroxypropionate bi-cycle were marginally affected when cells were grown heterotrophically with such organic substrates. The 3-hydroxypropionate bi-cycle in Chloroflexi is unique and was likely fostered in an environment in which traces of organic compounds can be coassimilated. Other bacteria living under oligotrophic conditions acquired genes of a rudimentary 3-hydroxypropionate bi-cycle, possibly for the same purpose. Examples are Chloroherpeton thalassium, Erythrobacter sp. strain NAP-1, Nitrococcus mobilis, and marine gammaproteobacteria of the OM60/NOR5 clade such as Congregibacter litoralis. |
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Authors:
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Jan Zarzycki; Georg Fuchs |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2011-07-15 |
Journal Detail:
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Title: Applied and environmental microbiology Volume: 77 ISSN: 1098-5336 ISO Abbreviation: Appl. Environ. Microbiol. Publication Date: 2011 Sep |
Date Detail:
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Created Date: 2011-08-25 Completed Date: 2011-12-13 Revised Date: 2012-03-01 |
Medline Journal Info:
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Nlm Unique ID: 7605801 Medline TA: Appl Environ Microbiol Country: United States |
Other Details:
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Languages: eng Pagination: 6181-8 Citation Subset: IM |
Affiliation:
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Mikrobiologie, Fakultät für Biologie, Schänzlestraße 1, D-79104 Freiburg, Germany. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Autotrophic Processes* Carbon / metabolism* Carbon Radioisotopes / metabolism Chloroflexus / growth & development, metabolism* Culture Media / chemistry Hydrogen / metabolism Metabolic Networks and Pathways Organic Chemicals / metabolism* Staining and Labeling / methods |
| Chemical | |
Reg. No./Substance:
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0/Carbon Radioisotopes; 0/Culture Media; 0/Organic Chemicals; 1333-74-0/Hydrogen; 7440-44-0/Carbon |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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