Termite guts are tiny microbial bioreactors converting lignocellulose to fermentation products, which in turn fuel the metabolism of the host. My research group studies the role of the termite gut microbiota in the symbiotic digestion, focusing on the biology of the prokaryotic and eukaryotic symbionts and their interactions, structure and functions of the intestinal ecosystem, and the evolution of its microbiota.
Other aspects are the microbial processes in the guts of humivorous soil macrofauna, such as soil-feeding termites and scarab beetle larvae.
The symbiotic digestion of lignocellulose in the termite gut requires a complex microbial community. In order to decipher the roles of the different microbial constituents and their contribution to the function of the microecosystem, we are constructing synthetic intestinal communities using a gnotobiotic model. Since it is not possible to produce germ-free termites due to their obligate relationship with their gut microbiota and their elaborate social system, we instead chose a closely related cockroach species. We have developed a protocol for generating germ-free cockroaches based on chemical sterilization of the egg cases. Hatchlings are raised in a sterile environment and then inoculated with autochthonous microorganisms or with termite gut microbiota. We are investigating the influence of microbial diversity on intestinal metabolic fluxes, particularly methanogenesis and reductive acetogenesis. Here, we want to clarify why in some termites molecular hydrogen formed by the primary fermenters is converted to methane by methanogenic archaea, whereas in others it is converted to acetic acid by homoacetogenic bacteria. The reason for the different metabolic fluxes is not understood, but is assumed to be founded in the species composition of the different trophic guilds and their functional interactions. The results will not only serve to obtain a better understanding of ecological principles, but also help in possible manipulations of methanogenesis in the intestinal tract of ruminants, which are next to rice fields the most important anthropogenic component of the global methane budget.