Biological Pretreatment of Lignocellulosic Biomass

Biological pretreatment harnesses the natural degradative capabilities of microorganisms—particularly fungi and bacteria—to overcome the intrinsic recalcitrance of plant cell walls. Lignocellulosic biomass comprises intertwined networks of cellulose, hemicellulose and lignin. The latter polymer acts as a physical barrier, impeding enzyme penetration and reducing carbohydrate yields. By deploying specialised microbes or consortia, biological pretreatment selectively disrupts lignin and hemicellulose, preserving fermentable sugars while operating under mild conditions without harsh chemicals or extreme temperatures. These processes can be applied as solid-state systems or combined with physical methods (for example, steam explosion) to enhance substrate porosity. The result is increased enzymatic saccharification efficiency, lower energy requirements and reduced formation of inhibitory by-products. Despite its sustainability benefits, challenges remain in scaling up, controlling process kinetics and reducing incubation times. Continued innovation in strain selection, process design and modelling is crucial for translating laboratory successes into economically viable biorefineries, thereby contributing to carbon-neutral energy and material cycles on a global scale.

Research from Nature Portfolio

Two key studies exemplify advances in fungal-mediated delignification. One evaluated a high-throughput screen of over sixty lignin-degrading fungi for corn stover pretreatment, identifying Myrothecium verrucaria as a potent agent secreting laccase, lignin peroxidase and manganese peroxidase. This biological pretreatment reduced lignin content by over 40 % and more than doubled subsequent sugar yields, with microscopic and spectroscopic analyses confirming efficient structural disruption of plant cell walls.

Another investigation optimised the sequential co-cultivation of Phanerochaete chrysosporium followed by Trichoderma viride on rice straw. A two-stage inoculation strategy achieved 26 % lignin removal and improved cellulose accessibility by one-third within eight days. This work provided a practical framework for integrating co-culture strategies into straw valorisation and underscored the critical role of fermentation parameters—such as inoculum timing, solid-liquid ratio and temperature—in maximising delignification efficiency.

Biological Pretreatment of Lignocellulosic Biomass publication trend

The graph below shows the total number of articles in biological pretreatment of lignocellulosic biomass across all publications each year (not limited to Nature Index journals).

Technical terms

Lignocellulosic biomass: Plant material composed of interlinked cellulose, hemicellulose and lignin, serving as a renewable feedstock for biofuels and bioproducts.

Delignification: The selective removal or modification of lignin to expose carbohydrate polymers for enhanced enzymatic access.

Solid-state fermentation: Microbial cultivation on moist solid substrates without free-flowing water, commonly used for fungal pretreatment of biomass.

Microbial consortia: Synergistic communities of multiple microbial species that collectively degrade complex substrates more efficiently than individual strains.

Enzymatic saccharification: The hydrolysis of polysaccharides into fermentable sugars by specific enzymes, following pretreatment.

References

1. Evaluation of Screened Lignin-degrading Fungi for the Biological Pretreatment of Corn Stover. Scientific Reports (2018).
2. Degradation enhancement of rice straw by co-culture of Phanerochaete chrysosporium and Trichoderma viride. Scientific Reports (2019).
3. The use of newly isolated fungal cultures for the selective delignification of bamboo culms. Frontiers in Bioengineering and Biotechnology (2023).
4. Degradation of lignin in different lignocellulosic biomass by steam explosion combined with microbial consortium treatment. Biotechnology for Biofuels and Bioproducts (2023).
5. Modeling the microbial pretreatment of camelina straw and switchgrass by Trametes versicolor and Phanerochaete chrysosporium via solid-state fermentation process: A growth kinetic sub-model in the context of biomass-based biorefineries. Frontiers in Microbiology (2023).