Fig. 4

a and b Scanning electron micrograph of Escherichia coli and Bacillus cereus. Prodigiosin (50 µg/ml) was added to the test organism and were then incubated for 2, 6, 18 and 24 h at 37 °C. The cell pellet was washed twice with potassium phosphate buffer (0.01 M; pH 7.0) followed by overnight fixing of the pellet with 2 % glutaraldehyde. Then, the pellet was dehydrated in ethanol on a gradient mode (10–100 %). Upon completion of the wash with 100 % ethanol, the pellet was spread on to the previously sterilized slide as a thin uniform layer and the slides were dried in a desiccator for SEM observation