Characteristics of cone-forming cyanobacteria and implications for the origin of conical stromatolites
Author(s)Evans, Alexander Joseph
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences.
MetadataShow full item record
Dating back to 3.5 Gya, stromatolites, which are composed of laminated and lithified carbonate rock, may contain the earliest records of phototaxis, photosynthesis, and oxygenation of the environment. The reconstruction of the co-evolution of biology and the environment using stromatolites depends on the ability to recognize macroscopic shapes that arise uniquely as a consequence of microbial processes. Our investigation aims to understand the biological factors in the formation of conical structures and stromatolites. To elucidate the role of the cyanobacteria, we enrich cyanobacteria from modern hot-spring communities of cone-forming microbes and subsequently test how the formation of conical structures depends on individual strains of the community. In our analysis, we augment morphological identification by genomic analyses of the 16S ribosomal DNA. Through a combination of mixing isolated heterotrophic bacteria and enriched filamentous cyanobacteria communities, we find that heterotrophic bacteria are a determinative factor in the formation and morphology of conical structures. Further, our experiments show the mere presence of a thin, filamentous cone-forming cyanobacteria phenotype is not a sufficient condition for cone formation.
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (pages 55-57).
DepartmentMassachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences.; Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
Massachusetts Institute of Technology
Earth, Atmospheric, and Planetary Sciences.