Modelling the biomineralisation processes which form calcite coccoliths

• Applicant: Professorin Dr. Annie Powell
• Subject Area: Biological and Biomimetic Chemistry
• Term: from 2001 to 2007
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5314974

One of the most intriguing aspects of the process of biomineralisation is the means by which organisms are able to direct crystallisation to produce a desired crystal phase and crystal shape. In previous work we were able to shed light on both nucleation and crystal growth processes in iron hydroxide based systems. We wish to apply our approach to the calcium carbonate system and, in particular, to the question of how the marine coccolithophore, Emiliana Huxleyi, is able to produce single crystals of calcite in the shape of hammer-like plates which then are used to construct the coccosphere around the organism. Our approach will involve screening the effect that oxygen containing templates have on the calcium carbonate system. These templates are designed to serve as models for various parts of the polysaccharide template which is thought to be important in directing the structures of the coccoliths in the native system. Of particular relevance is our observation that performing crystallisations under hydrothermal conditions allows us to observe intermediate phases which still incorporate the template and therefore allow us suggest how the template affects growth in certain crystal directions in order to produce the final shape of the (bio)mineral. The systems will also be investigated under standard conditions both to compare the effects of applying hydrothermal conditions and also to shed light on the early, nucleating events which may be in operation.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1117: Principles of Biomineralization