Caixia Wan, Yebo Li De La Cruz Jose, Escobar Bibiana
Fungal pretreatment of lignocellulosic biomass
ABSTRACT Operating parameters governing performance of the fungal pretreatment
Enzymes involved in biodegradation during the fungal pretreatment
Thermal/chemical pretreatment
Vs
Fungal pretreatment
The limitations and future perspective of this technology
The effect of fungal pretreatment on enzymatic hydrolysis and ethanol production Efforts for improving enzymatic hydrolysis and ethanol production through combinations of fungal pretreatment and physical/chemical pretreatment The treatment of lignocellulosic biomass with lignin-degrading enzymes isolated from fungal pretreatment, with a comparison to fungal pretreatment Modeling, reactor design, and scale-up of solid state fungal pretreatment
Lignin-degrading microorganisms and degrading enzymes
• Degradation of lignocellulosic biomass • white rot fungi are most effective for delignification due to their unique ligninolytic systems.
Degrading enzymes: Ligninolytic enzymes
Hydrolytic enzymes
• The Fenton system (Fe2+ and H2O2) • xylanase
Gene expression of ligninolytic enzymes • Expression of white rot fungi genes encoding ligninolytic enzymes is differentially regulated at the transcriptional level by the culture conditions. • Expression of LiP isoenzyme genes of P. chrysosporium is strongly influenced by nitrogen or carbon limitation. • Physiological factors agitation, moisture)
(e.g.
temperature,
Solid state fungal pretreatment process
• Inoculum • Moisture content • Particle size • Supplements
Solid state fungal pretreatment process
• Temperature • Aeration • Decontamination • Time
Enzymatic hydrolysis • Non-selective lignin degrading fungi • Selective lignin degrading fungi
Combination of fungal pretreatment and physical/chemical pretreatments
Enzymatic treatment
• White rot fungi may serve as a good producer of extracellular enzymes including oxidative enzymes and polysaccharide-degrading enzymes.
• El uso de enzimas ligninolíticas para el tratamiento directo de lignocelulosa, que solo lleva varias horas o días, tiene el potencial de superar los problemas del pretratamiento fúngico.
Modeling and scale-up • Solid state fungal pretreatment involves the degradation of the substrate taking place in absence (or near absence) of free water, due to release of extracellular enzymes or cell bound enzymes to the external environment. • The growth kinetics models, such as linear, exponential, logistic, and Monod equation, have been used to describe microorganism growth. • Heat generation related to metabolic activities of the microorganism growth causes temperature gradients in solid state fungal pretreatment. • Bioreactors have been developed for solid state fermentation, including tray reactors, packedbed, rotating drums, and stirred bioreactors.
Limitations and potentials • Fungal pretreatment with selective lignin degrading white rot fungi has been shown to have a significant impact on degradation. • Lignin degradation is the key indicator to the performance of fungal pretreatment. • Fungal degradation may occur slowly and thus long pretreatment time is required to achieve a relatively high lignin removal and cellulose saccharification.
Conclusions and future perspectives • White rot fungi with a high selectivity of lignin degradation over cellulose loss are important for fungal pretreatment. • Moisture and particle size of the feedstock, aeration, and pretreatment time are critical for fungal growth and metabolism to achieve good performance.
Bibliography • https://biotechnologyforbiofuels.biomedc entral.com/articles/10.1186/s13068-0170846-5 • file:///C:/Users/SAMSUNG/Desktop/term ina%20lignina.pdf • https://pubs.rsc.org/en/content/articlelan ding/2015/ra/c5ra09667g/unauth#! divAbstract