While carbon nanotubes (CNTs) possess diverse application potential ranging from polymer nanocomposites to nanostructured therapeutic devices, their environmental implications are still not well understood. In this study, we conducted experiments to monitor changes in bacterial physiology as a consequence of interactions with the CNTs. Our experiments included a common anaerobe, Escherichia coli, in an SWNT system as a model for understanding the environmental implications of CNTs. Observations over several weeks indicated that the bacteria in the presence of SWNTs showed significant morphological changes, that included elongation. It is interesting to note that similar morphological changes have been reported in response to extreme temperature and pressure, chemical agents, and quantum dots. In this presentation, the authors will present further physiological evidence, such as bacterial growth and substrate consumption rates, towards defining a possible bacteria-CNT interaction model consistent with these experimental observations, and will discuss the overall environmental implications.