Four different environmental DNA libraries were prepared from microbial consortium collected from forest soil, dung of elephant, cow rumen and rotted tree. Seven independent clones specifying cellulase activities (five endo-beta-1,4-glucanases and two beta-glucosidases) were isolated and identified. Sequence analysis of the retrieved genes revealed that the encoded products of these cellulase genes shared less than 50% identities and 70% similarities to cellulases in the databases. Domain analysis predicted that four endo-beta-1,4-glucanases conform to glycolsyl hydrolase family 5 (GHF 5) and one endo-beta-1,4-glucanase to glycolsyl hydrolase family 9 (GHF 9), while both beta-glucosidases belong to glycolsyl hydrolase family 3 (GHF 3). Further sequence analysis indicated that although a solid affiliation could be made for the two endo-beta-1,4-glucanases to the typical ruminal microbe Prevotella ruminicola, the rest formed deep-branched lineages with no close relatives. The revelation of the phylogenetic novelty provided a snapshot on the great diversity of cellulases in these natural environments.