FIG 3.

Heterogeneous extracellular matrix production at the surface of a macrocolony biofilm of E. coli K-12. The scanning electron micrograph shows an area behind the outer growth zone of the macrocolony of strain W3110. Only a subset of cells (arranged in small chains) are surrounded by a matrix of amyloid curli fibers, whose synthesis depends on high cellular levels of c-di-GMP. The image was previously published in this journal, as part of a larger figure (51).