Screening and identification of newly isolated cellulose-degrading bacteria from the gut of xylophagous termite Microcerotermes diversus (Silvestri).

The aim of the present study was to isolate and characterize the cellulose-degrading bacteria from the gut of the local termite, Microcerotermes diversus (Silvestri), inhabiting the Khuzestan province of Iran. The microorganisms capable of growing in the liquid medium containing cellulose as the only source of carbon were isolated and their cellulolytic activity on CMC-containing media was confirmed by the congo red clearing zone assay. The isolates were identified based on biochemical characteristics and the phylogenetic analysis of 16S rRNA gene fragments. The results of the present study show that three cellulose-degrading bacteria isolated from local termite guts belonged to the genera Acinetobacter, Pseudomonas and Staphylococcus and four cellulose-degrading bacteria belonged to Enterobacteriaceae and Bacillaceae families. Several isolates recovered from separate termite Microcerotermes diversus samples closely clustered in phylogenetic trees indicating high similarity and the abundance of particular cellulolytic strains. Bacillus B5B and Acinetobacter L9B hydrolyzed cellulose faster than the other isolates (with CMCase activity of 1.47 U/mL and 1.22 U/mL, respectively). The stability of CMCase produced by Bacillus B5B over a broad range of pH and high temperature indicated that the enzyme may be of great commercial value.