Taming lignocellulosic degradation activity of consortia from phytophagous insects guts in batch reactors: microbial diversity and enzymatic activities kinetics

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, acting synergistically, such as cellulosomes. Such structures remain associated to the microorganism membrane. 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 compare the efficiency of the microbial and enzymatic consortia that allow efficient lignocellulosic degradation. For this, the digestive microbiomes of three insects (Gromphadorrina potentosa, Potosia cuprea, and Locusta migratoria) were placed in fed-batch reactors, in physicochemical environment close to their original medium in a biomimetic approach. The microbiomes of insect guts were successfully maintained in bioreactors and their strategy for lignocellulose degradation was followed dynamically in successive fed-batch reactors. Their ability to degrade lignocellulosic substrate (wheat straw) as well as their microbial and enzymatic diversity allowed comparing the efficiency of these potential bioressources. This research will enable to identify the microbial species and 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.