Diversity and dynamics of microbial communities have been analysed by culture-dependant methods, which exclude the majority of fastidious microbes due to the selective nature of the media. Molecular methods have been used to determine diversity of microbial communities, but indicate the genetic complexity within a comminity. An alternative approach is to examine components of functional biodiversity (i.e. substrate utilisation), for which there exists a reasonable chance of detecting patterns, which could be related to the functional diversity of the species present in the community. In this study, different carbon source profiles were generated by inoculating Biolog GN and GP microtitre plates, with different dilutions of microbial communities. The high number of substrates utilised at the lower dilutions indicated a high functional diversity in the communities tested. This, however, did not necessarily reflect the evenness of the functionality. Functional evennness of each species was reflected upon further dilution. Our results indicated differences in the functional diversity of the microbial communities amongst some of the natural environments studied. The results indicated that evenness and dominance can be demonstrated by mixtures of cultures as well as in natural environments.