Surface growth is a key feature of bacterial action in nature. The E. coli colony is an excellent model system of bacterial surface populations. It is a highly organized structure characterized by differential gene expression. Cell-cell interactions over distances of microns regulate the growth of individuals cells, and gene expression patterns can be coordinated between populations separated by distances of millimeters. Diffusible signals affect several aspects of colony development. Genetic loci subject differential control during colony development have been identified by spontaneous and transposon insertion mutations and the use of lacZ fusions. In addition, the cAMP system has been implicated in activating the spatially localized replication of Mudiac elements. The experimental program will extend these initial observations by detailed study of three systems:(1) developmental regulation of the dev1891::lacZ fusion. (2) the role of DNA polymerase 1, the cAMP system, and diffusible substances in the control of Mudiac replication, and (3) the dev2137 and dev2137 mutations located in the oriC region of the chromosome. The results will specify gene products involved in colony morphogenesis, provide a more detailed picture of differential gene expression during growth on an agar surface, and identify diffusible signals that affect colony developments.
