Growth and morphology of Asticcacaulis biprosthecum in defined media

The growth and morphology of cells of Asticcacaulis biprosthecum were studied in defined media to determine the effects of various compounds on the growth rate and on the expression of morphological events of the life cycle. The length of prosthecae could not be controlled by varying the concentration of inorganic phosphate as has been shown for other caulobacters. In defined media, growth was inhibited during conditions favoring rapid metabolism, apparently due to an absolute requirement for cells to complete all stages of the life cycle before cell division could occur. The morphology of cells grown under these conditions was aberrant, i.e., cells appeared elongated and branched and few prosthecae or swarmer cells were produced. Growth of a related bacterium, Asticcacaulis strain S-3, was not inhibited by conditions favoring rapid metabolism. During rapid growth, cell division in this organism occurs in the swarmer stage and prosthecae are not produced. Cell division in S-3 is not obligately coupled to completion of all stages in the complex life cycle, and morphogenesis can be controlled by cultural conditions.