Characteristics of cone-forming cyanobacteria and implications for the origin of conical stromatolites

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.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2013

Author dc:creator

• Evans, Alexander Joseph

Advisor dc:contributor.advisor

• Tanja Bosak.

• Earth, Atmospheric, and Planetary Sciences.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/84913

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/84913