Two types of bacteria were placed on the top surface of carbon nanotube films and the composite film morphology was examined using scanning electron microscopy. The interaction of bacteria with the carbonaceous film was studied after drying and subsequent heating to 1000 °C. For gram-positive bacteria, subsequent shrinkage of the bacterial layer causes film stresses and roll-up, and for the gram-negative bacteria the carbonization step seems to leave residual bacterial-derived material in-between the Single-Walled Carbon NanoTube (SWCNT) network, suggesting some type of interaction between the SWCNTs and the bacterial wall that leads to incorporation of material within the network, which then carbonizes. These observed property changes are undesirable during the lifetime of the material network, but might be welcome for its later disposal.