One of the fundamental challenges in microbial ecology is to examine how microbial communities that differ in composition may also differ in function.  Since the advent of molecular techniques, we have become increasingly proficient at analyzing community structure to fine taxonomic levels, and with ever-increasing depth of coverage.  However, we have made less progress in understanding the aspects of microbial ‘function’ that differ between communities.  I argue that this is largely due to our traditional approach of measure microbial activities at optimal conditions in potential assays.  While this approach allows for comparisons across space or time, or in response to experimental treatments, it provides little information on the rate of these activities under in-situ conditions. 

Results/Conclusions

Using a simple niche framework, I will explain why this approach is unlikely to reveal functional differences between communities.  An emerging new paradigm of microbial function emphasizes (1) the range of conditions under which a function can persist, and (2) the persistence of microbial function in response to stress or disturbance.  These novel aspects of function are much more closely linked to microbial community composition than optimal activity rates under ideal conditions which are rarely seen under in-situ conditions.  I will also discuss the promises and perils of emerging molecular technologies including proteomics and metabolomics, which will provide new insights into novel aspects of microbial community function.