Abstract: The current study established laboratory microcosms consisting of aquatic bacterial community, and bacteria operational taxonomic units (OTUs) were identified by unique terminal restriction fragment lengths. The results showed that at a local scale (i. e., a single culture flask), a Ushape pattern was found between productivity and bacterial TRF. However, a positive relationship was revealed at a regional scale (i. e., a set of three replicated flasks). Therefore, the current study demonstrated that productivityrichness relationship was scaledependent. Future studies should apply highthroughput sequencing methods to solve the technical problem that the majority of microorganisms are uncultivable under laboratory conditions, and to better understand the diversity and distribution patterns of microbial communities, as well as important ecosystem functions and services they provide.