2-11: Development of an anaerobic, thermophilic and cellulolytic consortium to improve anaerobic digestion of lignocellulosic biomass

Over the last years, the development of green industrial processes using products from plant biomass induced an important increase of lignocellulosic by-products. Anaerobic digestion of this organic matter can be an attractive option as a source of alternative energy. Moreover, this biological mechanism is also the only degradation pathway occurring in the landfill where organic fraction of municipal solid waste is buried. The low biodegradation rate of this biomass is an important obstacle in anaerobic microbial decomposition process. The principal rate-limiting step in anaerobic digestion is the lignocellulosic biomass hydrolysis. Our research aims at developing an anaerobic consortium able to degrade lignocellulosic products in thermophilic conditions to improve methane production.

A thermophilic cellulolytic microbial consortium was obtained from high temperature compost after enrichment cultures. The hydrolysis potential of the miccrobial community on different (ligno)cellulosic substrates in anaerobic and thermophilic conditions was evaluated. We tested first the potential on two reference substrates, filter paper and microcrystalline cellulose. The consortium was able to hydrolyze almost all the matter present in the experimental medium in six days. After these promising results on pure cellulosic substrates, the tests were realized on wheat bran, a lignocellulosic by-product. The consortium also hydrolyzed an important part of this biomass. These encouraging results make us believe that this consortium could be use as a microbiological tool to remove the rate-limiting step in anaerobic digestion and so to improve the methane production. This hypothesis will be tested during next months.