Mining the microbiomes from marine wood-digesting bivalves for novel lignocellulose depolymerizing enzymes
Lignocellulose is a greatly undervalorized biomass and methodologies to convert it to high-value products needs fortification. This plant-derived raw material is the most abundant biomass in Europe and it can be harvested from waste streams found in forest and agricultural industries. A functional bioeconomy depends on the ability to convert lignocellulose to chemicals and fuels, a process called biorefining, which still is in its infancy. A critical step in biorefining is the enzymatic conversion of lignocellulose to soluble sugars and lignin. The cost and the efficiency of enzymes is far from optimal and new enzymes are needed to improve the efficiency and sustainability of lignocellulose depolymerization. Through MetaMine, we will exploit the process strategies of nature’s own micro-biorefinery, the shipworm.
Shipworms are voracious animals with respect to their appetite for wood. These marine bivalves are causing severe damage to all wood found in the sea worldwide. Their digestive system is especially intriguing. Wood engulfed by mechanical rasping is digested by enzymes secreted by a community of symbiotic bacteria located in the gill tissue. Current model systems for the study of cellulose degradation are highly complex (e.g. community driven anaerobe systems in ruminants and the intricate secreted enzyme systems of aerobic fungi), and challenging to analyze. The shipworm gill symbionts are specialists in lignocellulose degradation and perform this task by applying a perfected enzyme cocktail in a defined and physiochemically stable environment. Thus, by unravelling the contributions of the individual enzymes in the shipworm cocktail, we have the opportunity to take a leap forward in understanding the fundamental properties of enzymatic lignocellulose degradation. MetaMine will use the shipworms as a model system for a holistic study of marine lignocellulose degradation and mine the metagenomes for novel lignocellulose depolymerizing enzymes.