Bacilla vitruvius

Bacilla Vitruvius Shells occupy an iconic status within architecture and have been used as an emblem for scale and proportion as well as providing the basis of many types of building materials. In addition, shell formation is a good example of the complex relationship between biological mechanisms and the construction of both organic and inorganic materials. An abalone constructs its shell by first forming soft tissues through morphogenesis (the process by which the organism’s cells organise into a pattern). The organism doesn’t build its shell directly but instead these tissues act like a scaffold and the abalone alters the chemical composition of its outer surface in order to induce calcium in its environment to combine with carbon and crystalize through a process called biomineralization. Furthermore, by altering the chemical environment through the addition of extra cellular substances, the shell shifts between different crystalline structures from the inner layer of flat plate-like crystals (sometimes referred to as mother of pearl) to the outer layer which is made up of vertical crystals to create an exceptionally strong surface (Lin, Chen, & Meyers, 2008).

By controlling this process of mineralization, the abalone constructs a single material with the properties of a composite material and creates a structure with significant strength with very little expenditure of energy. This is a fascinating process, not least because the status of the shell is ambiguous. Its form and material are products of its environment and, although it is not living, it cannot be considered as entirely inorganic. Both biomineralization and morphogenesis are often studied independently in science and this proposal makes use of a number of recent scientific breakthroughs .

The two processes are rarely studied together in science, however, and have never been studied together in the context of design. Biomineralization has been studied in the context of the built environment as a way of creating new ‘self healing’ materials; and through design speculations such as Magnus Larson’s proposal to create new sandstone structures through the consolidation of sand dunes and Rachel Armstrong’s proposal to refloat Venice through the building of a protocell induced calcium carbonate reef. Aside, however, from the potential applications of biomineralisation, the process itself is worthy of further study, particularly in relation to bacteria induced calcium carbonate which can be seen as a prototype for processes seen in more complex organisms such as abalones. Over the two years we have developed two pilot studies on bacteria induced mineralization, both undertaken in collaboration with Northumbria University, linking PhD. and Masters students in Architecture with a Researcher in Biochemistry (Dr. Meng Zhang) .

The results of testing different bacteria under different chemical and physical conditions led to a wide range of different crystal morphologies and patterns. The key outcome was the demonstration of a process which begins to link the design of macro structures to microscale effects and fosters an understanding of the relationship between biological, chemical and physical constraints on the state space of this type of material construction.