Morphological changes (including filamentation) in Escherichia coli grown under starvation conditions on silicon wafers and other surfaces

Using a scanning electron microscope, pleomorphism (notably filamentation) was seen when Escherichia coli was grown under starvation conditions for 14 d on microporous silicon wafers, titanium, glass and plastic discs. Under these conditions, the 'standard', rod shaped cell (1-3 mu m) failed to sepa rate after division and filaments developed, some as long as 50 mu m, with many showing bulbous tips. Filamentation began to occur 5 d after the impos ition of starvation conditions. Dumbbell shaped cells were also observed, a lthough apparent 'Y' and 'V'-shaped cells proved to be artefacts, caused by overlapping rods. The implications of the appearance of pleomorphism in E. coli, when grown under starvation conditions, is discussed in relation to its pathogenicity and growth in the environment.