Cell division in blue-green bacteria: stimulation of localized regions of peptidoglycan metabolism by ethanol.

D-Cycloserine was used to localize regions of active peptidoglycan metabolism as bulged, weakened areas in the lateral wall. Strain SN29 is a non-septate filamentous mutant of Agmenellum quadruplicatum and produces one to two such bulges per filament during exponential growth in the presence of D-cycloserine. The addition of ethanol to D-cycloserine inhibited filaments results in the production of many additional bulges in the lateral wall and is interpreted as evidence for the localized activation of peptidoglycan metabolism by ethanol. In the parent organism, D-cycloserine selectively inhibits cell division resulting in the formation of enlarged spindle-shaped cells. Cell separation was also affected. Chain formation was greatly reduced in septate mutants of A. quadruplicatum by growth in the presence of D-cycloserine. This was apparently due to the increase fragility of cells within the filaments.