Cellulolytic Activities of the Dung Beetle, Euoniticellus Intermedius, Larva Gut Micro-Flora

The life style and biology of dung beetles offer a significant opportunity for innovation in biofuel production. The larvae of the African dung beetle, Euoniticellus intermedius, feed solely on cow dung, eating and digesting the fibre while adults live on juices found in fresh dung. The larval gut system consists of a small, almost unrecognizable foregut and two distinct chambers; the midgut and hindgut. It is clear that these two chambers are the centres in which the dung material whose composition includes cellulose is processed. The goal of this study was to assess the cellulolytic activities of cultured gut micro-flora derived from E. intermedius, (Coleoptera: Scarabaeida).

Late second to third instar stage E. intermedius larvae were dissected and the isolated gut micro-flora consortia aerobically cultured in media containing cellulose (filter paper) as the sole carbon source. Genomic DNA isolation was done on the gut consortia cultures after 10 days of culturing, using the ZR Fungal/Bacterial DNA MiniPrep kit (Zymo Research, USA). A complete and unbiased primary cosmid library was then constructed from the isolated genomic DNA using a cloning ready, pWEB-TNC™ Cosmid Cloning kit (EPICENTRE Biotechnologies, USA). The primary cosmid library clones were screened for endo-glucanase and cellobiohydrolase activities using Carboxymethyl Cellulose (CMC) and 4-Methylumbelliferyl-β-D-Cellobioside (MUC) plate assays respectively.

Results indicate that a total of 7 colonies out of 160 screened colonies showed positive CMC and MUC activities.

This proves that E. intermedius is a potential source of cellulolytic micro-organisms and enzymes that can be used for cellulose derived biofuel production.