One of the greatest future challenges is to meet the growing demand for energy and raw material supply in a sustainable manner, simultaneously reducing the greenhouse gas emissions. Today, the transportation sector consumes more than half of the annually produced oil. In India, around 90% of the growth in energy consumption comes from the transportation sector.
Therefore, renewable raw materials for transportation fuels are of particular interest, especially fuels produced from lignocellulosic wastes and residues. In order to effectively convert lignocellulosic biomass to fermentable sugars, enzymatic hydrolysis is currently the most environmentally sustainable technology. The IndZyme project proposal focuses on improvement of the enzymatic hydrolysis by developing robust enzymes and increasing knowledge on enzyme inhibition and inhibitors formed in the biomass pretreatment.
Pretreatment, enzymatic hydrolysis and fermentation are the major steps in biochemical conversion of lignocellulosic raw materials to renewable fuels and chemicals. Despite recent developments, the enzyme cost still remains a bottleneck to the process feasibility. High-temperature pretreatments are used to overcome the resistance of the materials towards enzymatic hydrolysis. As a result, inhibitory compounds such as phenolics, furans and organic acids are produced that inhibit both enzymes and fermentation organisms. In the biorefinery processes, enzyme inhibition is emphasized by the high solids concentrations required for hydrolysis process efficiency.
The IndZyme project is built upon the novel idea of screening for inhibitor tolerant cellobiohydrolases (CBHs) and lytic polysaccharide monooxygenases (LPMOs) from microbes isolated from fire-prone forests of India. Forest-fire residues contain chemicals similar to the inhibitors found in lignocellulose materials that have been processed at high temperatures. Microbes extracted from fire-prone areas have been shown to adapt for these chemicals, such as furans, and have improved thermotolerance.
Besides inhibitory effects, the lignocellulose-derived phenolics have been shown to act as electron donors for the oxidative catalysis by LPMOs, but the interactions are still poorly understood. The importance of LPMOs in lignocellulose hydrolysis has only recently been discovered and understanding the role of pretreatment-derived compounds for LPMO catalysis is of major importance for improving their applicability in biomass processing. The IndZyme project aims at characterization of both the positive and negative interactions of the lignocellulosic compounds on enzymes, with particular focus on the phenolic compounds.
The IndZyme project aims at discovery of novel inhibitor-tolerant CBHs and LPMOs and improvement in the efficiency of biomass processing through understanding the complex interactions between the enzymes and lignocellulose-derived compounds.
The unique culture collection of VINSTROM (India) containing fungi isolated from fire-prone forests will be used as a source for enzyme screening. Novel screening methods will be developed based on lignocellulose-derived compounds, produced and characterized jointly between VTT (Finland) and RWTH (Germany). Molecular biology expertise at VTT is utilized for identification and production of then novel enzymes, which are then characterized together by VTT and University of Tartu (Estonia).
The project relies on the complementary expertise of the research partners, establishing fruitful international and intercontinental collaboration.