Exploring enzymatic behaviour in xylo- and phytophagous insects consortia. What could be learned from Nature ?

Over millions of years living organisms have optimized the digestion of a large variety of substrates resulting in highly efficient systems [1, 2]. The microorganisms found in animal digestive tracts where oxygen is deficient, generally produce enzymes assemblies, such as cellulosomes, which remain associated with microorganisms and act in synergism. Many insects feed on plant material and benefit for the degradation of lignocellulose of an endosymbiosis with bacterial population located in their digestive tracts. The study of original strategies implemented in insect guts would be of interest for possible improvements of the biomass conversion in industrial processes. The proposed project aims to characterize the microbial and enzymatic consortia that allow efficient lignocellulosic degradation. For this, the digestive microbiomes of nine insects belonging to several orders (Gromphadorrina potentosa, Ergates faber, Potosia cuprea, Propomacus bimucronatus, Gryllus bimaculatus, Locusta migratoria, Cossus cossus, Carausius morosus and Termites hospes) were placed in batch reactors, in physicochemical environment similar to their original medium. Their ability to degrade lignocellulosic substrate (wheat straw) and the characterization of their phylogenetic and enzymatic diversity allowed selecting the most efficient insects. The microbiomes of selected insects were successfully maintained in bioreactors and their strategy for lignocellulose degradation was followed dynamically in successive fed-batch reactors. This research will enable to analyze the genes and the microorganisms that synthesize the enzymes of interest and therefore to produce biomimetic enzyme cocktails benefiting from millions of years of evolution.