Summary

PREDIG is a multidisciplinary collaboration that integrates the experimental and theoretical expertise of the two work packages to develop a free, open-source, and user-friendly software tool to predict enzymatic saccharification of lignocellulosic biomass. The modelling approach follows a Gillespie algorithm to conduct stochastic simulations of the saccharification dynamics of a three-dimensionally resolved lignocellulose microfibril, which can vary in composition, structure and crystallinity; that is being digested by a tuneable enzyme cocktail consisting of cellulases and hemicellulases.
As an experimental approach, Phosphoric Acid OrganoCat (OrganoCatPA) treatments without (1) and with (2) an additional swelling step were chosen, to understand the impact of the crystallinity and cellulose impurities on enzymatic hydrolysis of diverse biomasses. Four representative biomasses were selected based on chemical composition analysis. OrganoCatPA treatments significantly improved cellulose purity, reduced matrix polysaccharides (MPS) and lignin content, resulting in higher crystallinity index (CI) for OrganoCatPA(1) pulps. OrganoCatPA(2) with swelling showed variable CI results. Enzymatic hydrolysis revealed varying glucose yields per cellulose content in the plant, with Sida exhibiting the highest yield. OrganoCatPA treatments, especially OrganoCatPA(1), significantly enhanced saccharification yields, despite lower overall impurities and crystallinity in OrganoCatPA(2) pulps. Comparisons with commercial celluloses and lignin-cellulose mixtures highlighted the impact of lignin on saccharification efficiency. The study concludes that the effects of swelling on pulp depend on lignocellulose type, and factors beyond crystallinity play a crucial role in enzymatic saccharification.
The software has been released as an open-source web application accessible at https://predig.cs.hhu.de/. Apart from the release of the web application, the project has resulted in not only the design of the OrganoCat processing technique which enhances lignocellulose fractionation but also a deep sensitivity analysis which has highlighted the key factors that modulate lignocellulose saccharification. Both of them have been published as peer-reviewed articles.

Results

As overall goal of the BioSC Seed Fund 3.0 project PREDIG, the team led by Dr Adélaïde Raguin (HHU Düsseldorf) has successfully developed a Web Application to simulate biomass saccharification, that is now online available and published in the Computational and Structural Biotechnology Journal.