Our research aims to better characterize the diversity of bacteria in natural microbial communities by type and function. Over 99% of environmental microbes are believed to be yet uncultivable, hence we rely primarily on culture-independent molecular methods to gather information on the composition and role of mixed microbial communities. Some uncultivable bacteria found in environmental samples are also present in humans, and some of those bacteria have been recently associated with human diseases. Our research attempts to discover the natural source of human-associated uncultivable bacteria and to compare the function of those bacteria in their natural environment as well as in the human body. To study function of microbes, we combine in situ hybridization with micro-autoradiography (STARFISH) to determine the types of nutrients a particular bacterium is able to take up without the need of cultivation. Such method may aid in determining more appropriate cultivation media for isolating yet uncultivable bacteria. Updates at www.ouverneylab.com.