Bacterial macrofibres: the morphogenesis of complex multicellular bacterial forms.

Bacterial macrofibres are highly ordered multicellular, helically twisted structures that provide a unique opportunity for studying fundamental growth processes and morphogenesis in a procaryotic model. The complex fibres arise, starting either from a single spore or a vegetative cell by the deformation of individual cell shape from cylindrical to helical and the folding and plying of chains of cells into multicellular twisted structures. The dynamics of fibre morphogenesis can be traced to hierarchical interactions beginning with the assembly of cell-wall polymers. Both genetic and biomechanical factors govern the formation and heritability of macrofibre twist states, which can range over the entire spectrum from maximum left- to maximum right-handedness. Forces that arise during growth influence individual cells and their interactions with other cells. Morphogenesis results from the manner in which the cell-wall materials respond to these and other forces. Significant parameters governing response to force are cell wall geometry, visco-elasticity and anisotrophy.