Physiological and molecular basis of symbiotic interactions in phototrophic consortia
Final Report Abstract
The phototrophic consortium “Chlorochromaticum aggregatum” provides the unique opportunity to study two different bacteria in a close and structured interaction. Few bacterial associations have reached this complex organization level and can be kept in a laboratory culture. The conducted studies significantly contributed in further understanding the interaction between the two partners of “C. aggregatum” on several different levels. (i) “Ca. S. mobilis” can sense light and probably sulfide, which are directly beneficial to Chl. chlorochromatii. In return, the central bacterium receives fixed CO2 in the form of small organic matter, most likely as amino acids. The uptake of these substrates could be mediated by the multitude of transcribed transporters identified in the central bacterium. Also the flux of carbon changes depending on the nitrogen availability of the epibiont cell, indicating a complex picture of substrate utilization within the phototrophic consortium. A surprising result was the finding that the consortium does not solely grow on dinitrogen gas, contrary to what had previously been assumed when the association with a green sulfur bacterium, capable of nitrogen fixation, was considered a competitive advantage. (ii) This study identified several subcellular elements of epibionts as well as of central bacteria. Some of these structures appear to be highly specific for phototrophic consortia and hence are likely to be involved in either the cell-cell aggregation or the physiological interaction. (iii) In addition symbiotic proteins were identified and proven to be transferred from the epibiont to the central bacterium (Cag_1919, Cag_0614, Cag_0616). It was shown that RTX and RGD motifs, known from pathogenic interactions, are being used in the symbiotic interaction between two prokaryotes. Although the transfer of proteins is not conclusive evidence of signal exchange, the proven protein transfer into the central bacterium indicates the involvement of these transported proteins in the partner organism.
Publications
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(2007) Heterotrophic symbionts of phototrophic consortia: members of a novel diverse cluster of Betaproteobacteria characterized by a tandem rrn operon structure. Environ. Microbiol. 9: 2782-2794
Pfannes, K. R., Vogl, K., Overmann, J.
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(2008) Phototrophic consortia – model systems for the interaction between nonrelated bacteria. In: Liu, S.-J., Drake, H. (eds) Microbes and the Environment: Perspective and Challenges. Science Press, Beijing. p.79-85
Overmann, J.
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(2008) Ultrastructural Characterization of the Prokaryotic Symbiosis in “Chlorochromatium aggregatum”. J. Bacteriol. 190: 3721-3730
Wanner, G., Vogl, V., Overmann, J.
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(2008). Identification and analysis of four candidate symbiosis genes from “Chlorochromatium aggregatum”, a highly developed bacterial symbiosis. Environ. Microbiol. 10: 2259-2856
Vogl, K., Wenter, R., Dressen, M., Schlickenrieder, M., Plöscher, M., Eichacker, L., Overmann, J.
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(2009) Ultrastructure, phylogeny and tactic behaviour of a novel multicellular magnetotactic prokaryote from North Sea sediments. Environ. Microbiol. 11: 1493-1505
Wenter, R., Wanner, G., Schüler, D., Overmann, J.
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(2010) Phototrophe Konsortien - hoch entwickelte mehrzellige Symbiosen. BIOSpektrum 04.10: 392-394. - Auch erschienen in: Jahn, D. (ed.) (2012) Zellbiologie und Mikrobiologie - Das Beste aus BIOspektrum. Springer Spektrum
Overmann, J.
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(2010) The phototrophic consortium "Chlorochromatium aggregatum" – a model for bacterial heterologous multicellularity. In: Hallenbeck, P.C. (ed.) Recent Advances in Phototrophic Prokaryotes. Adv. Exp. Med. Biol. 675: 15-29
Overmann, J.
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(2010). Expression-based identification of genetic determinants of the bacterial symbiosis “Chlorochromatium aggregatum”. Environ. Microbiol. 12: 2259-2276
Wenter, R., Hütz, K., Dibbern, D., Li, T., Reisinger, V., Plöscher, M., Eichacker, L., Eddie, B., Hanson, T., Bryant, D.A., Overmann, J.
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(2011) Close interspecies interactions between prokaryotes from sulfureous environments. Front. Microbiol. 2: 146
Müller, J., Overmann, J.
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(2012) Comparative and functional genomics of anoxygenic green bacteria from the taxa Chlorobi, Chloroflexi, and Acidobacteria. In: Advances in Photosynthesis and Respiration, Vol. 33, Functional Genomics and Evolution of Photosynthetic Systems, (Burnap, R. L. and Vermaas, W.F.J., eds.), pp. 47-102, Springer, Dordrecht, The Netherlands
Bryant, D. A., Liu, Z., Li, T., Zhao, F., Garcia Costas, A. M., Klatt, C. G., Ward, D. M., Frigaard, N.-U., Overmann, J.
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(2013) Genomic analysis reveals key aspects of prokaryotic symbiosis in the phototrophic consortium “Chlorochromatium aggregatum”. Genome Biol. 14: R127
Liu, Z., Müller, J., Li, T., Alvey, R.M., Vogl, K., Frigaard, N.U., Rockwell, N.C. Boyd, E.S:, Tomsho, L.P., Schuster, S.C., Henke, P., Rohde, M., Overmann, J., Bryant, D.A.
