COMPARATIVE IMAGING OF PSEUDOMONAS-PUTIDA BACTERIAL BIOFILMS BY SCANNING ELECTRON-MICROSCOPY AND BOTH DC CONTACT AND AC NONCONTACT ATOMIC-FORCE MICROSCOPY

Both Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (A FM) have been used to visualize the morphology of Pseudomonas putida b acterial colonies isolated from model oil-in-water emulsions. A new me thod has been developed for growing flat homogeneous bacterial biofilm s at planar oil-water interfaces. A marked increase in resolution has been achieved when these flat bacterial biofilms are imaged by both SE M and AFM methods. On flat bacterial biofilms AFM offers superior reso lution with minimal sample preparation. High resolution DC contact mod e AFM studies of the bacterial surfaces have revealed surface features comparable in size to large proteins. AC non-contact AFM methods hare been used to image bacterial flagella trapped in the biofilm.