Figure 5
Role of A. flavithermus cells and biofilms in silica precipitation. (a) Subaqueous amorphous silica (opal-A) precipitated on glass substrate (dark gray). (b) Heavily silicified and unsilicified A. flavithermus cells showing a discontinuous sheath of uniform thickness surrounding one cell. (c,d) Association of silica precipitates with the extracellular matrix produced by biofilm-forming cells of A. flavithermus. (e) A. flavithermus biofilm with extensive granular silica precipitates. The glass substrate to the left shows little silica precipitation and would resemble (a) under high magnification. (f) Extensively silicified A. flavithermus biofilm showing variably silicified cells and a continuous outer coating of silica. Each plate represents a scanning electron microphotograph with scale bar as shown in the bottom right corner.