PHENOLIC ALDEHYDES AND FURFURAL DEGRADING FUNGI FOR THE BIOLOGICAL PRETREATMENT OF LIGNOCELLULOSIC BIOMASS

ZANELLATI, A; SPINA, F; RODRIGUEZ, F; MARTÍN, M; VARESE, GC; SCARPECI, TE

Congreso; SAMIGE 2020 (SAIBSAMIGE 2020); 2020

Lignocellulosic biomasses, such as agricultural andforest residues, represent an abundant, renewable, and low-cost resources toproduce biofuels, chemicals, and polymers. The recalcitrant nature oflignocellulosic biomass is the major issue for its exploitation inbiotechnological processes. Physicochemical pretreatments are used to improvethe bioconversion of this type of biomass, but they could generate toxicby-products, as furan and phenols, that could inhibit several biologicalprocesses. In this study, 40 fungal strains were analyzed for their capabilityto grow with different concentrations of furfural (F) derived from dehydrationof hemicellulosic carbohydrates, and the lignin derivatives vanillin (V),4-hydroxybenzaldehyde (H), and syringaldehyde (S). Growth performance of fungalstrains was analyzed at different concentrations of the inhibitors, as singlemolecules or mixes of them. The high-throughput screening performed withthe 40 fungal strains confirmed the strong toxicity of phenolic aldehydes andfurfural. Furthermore, results showed that in the presence of single moleculesolutions, the growth inhibition depends not only on the nature andconcentration of the assayed compounds but also on the presence of glucose asco-substrate. Byssochlamys nivea MUT 6321 showed promising growthperformance when the inhibitors were used as single molecules and it was theonly fungus that could grow when the four molecules were simultaneously presentin culture media. The capacity of B. nivea to degrade F and the phenolicaldehydes was analyzed by monitoring the residual concentration of eachcompound in the media using HPLC. B. nivea was able to completely degrade furfural in 24 h. Asregards the phenolic aldehydes, results showed that 99 % of H, S, and V weretransformed after 4, 9, and 11 days, respectively. B. nivea completelydegraded V, H, and S present in the mix of the three molecules (MP mix).However, when F was present in the mix (MPF), a faster and preferentialconsumption of F instead of phenolic aldehydes was observed. Furthermore, V, H,and S in the MPF mix showed a delay in their transformation in comparison to MPmix. This finding could be explained considering that F and the phenolicaldehydes are molecules with different chemical structures and may then requirethe activation of different catabolic mechanisms, demanding time and resourcesto accomplish it. This preference in toxic molecules transformation is apromising feature of B. nivea, considering that phenolic compounds, suchas S and V, were reported to have less impact than F on biotechnologicalprocesses. In conclusion, this study highlights the importance to explorefungal biodiversity to discover new strains for future biotechnologicalapplications and provides importantinformation for the use of B. nivea to remove toxic compoundspresent in pretreated lignocellulosic biomass that could potentially lead tothe enhancement of biofuels and chemicals production.