The Procedure Followed for SEM

The various bifidobacterial strains were harvested, and washed twice with phosphate buffer. The pelleted bacteria were fixed in 2% glutaraldehyde and incubated at 4°C 1 h/overnight. The cells were then harvested and washed with a 10–100% gradient of ethanol. The cells were resuspended in 50–100 μl of absolute alcohol. Approximately 2 μl of the sample was placed on a cover slip, dessicated and examined with SEM. The images were collected at 20,000 magnifications. Only appropriate and convincing images were considered in the analysis.