Document Type : Research Paper
Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-carlense 400, 13566-590 São Carlos, SP, Brasil.
PhotoBioCatalysis Unit - BioCat, CPBL and BTL departments, Interfaculty School of Bioengineers, Université libre de Bruxelles, Campus de la Plaine, Bd. du Triomphe, Acc.2, CP 245, 1050 Bruxelles, Belgium.
Cost-efficient plant biomass conversion using biochemical and/or chemical routes is essential for transitioning to sustainable chemical technologies and renewable biofuels. Lytic polysaccharide monooxygenases (LPMOs) are copper-dependent enzymes that make part of modern hydrolytic cocktails destined for plant biomass degradation. Here, we characterized MtLPMO9A from Thermothelomyces thermophilus M77 (formerly Myceliophthora thermophila) and demonstrated that it could be efficiently driven by chlorophyllin excited by light in the presence of a reductant agent. However, in the absence of chemical reductant, chlorophyllin and light alone do not lead to a significant release of the reaction products by the LPMO, indicating a low capacity of MtLPMO9A reduction (either via direct electron transfer or via superoxide ion, O2•-). We showed that photocatalysis could significantly increase the LPMO activity against highly crystalline and recalcitrant cellulosic substrates, which are poorly degraded in the absence of chlorophyllin and light. We also evaluated the use of co-substrates by MtLPMO9A, revealing that the enzyme can use both hydrogen peroxide (H2O2) and molecular oxygen (O2) as co-substrates for cellulose catalytic oxidation.
- MtLPMO9A can be efficiently activated by light at the presence of chlorophyllin.
- Photoactivation improves performance of MtLPMO9A on crystalline cellulose.
- MtLPMO9A can use both O2 and H2O2 as co-substrates.
- For H2O2 reactions MtLPMO9A requires chemical reductant.
- Photobiocatalysis mediated by LPMOs might play a role in plant biomass valorization.