A highly cellulolytic consortium was serially diluted and incubated in fermentation medium with filter paper as carbon sources. The critical dilution point of the consortium for effective degradation of filter paper was 10(-5) as further dilution resulted in the loss of degradation ability of filter paper accompanied by the disappearance of four bands in denaturing gradient gel electrophoresis profiles. The loss of bands corresponding to 16S rRNA sequences from Clostridium clariflavum DSM 19732 and a Paenibacillus species coincided with the loss of degradation ability of filter paper. (C) 2012 Elsevier Ltd. All rights reserved.