Lignin chemical controls on bioconversion of tropically grown C₄ bioenergy grasses to biofuels and biobased products

Converting lignocellulose to bioenergy and biobased products requires targeted breakdown of complex plant polymers that protect structural sugars. To identify lignophenolic compounds that promote enzymatic hydrolysis, the lignophenolic composition of biomass across 12 species and varieties of the Poaceae (grass) family were measured using copper (II) oxide (CuO) oxidation and gas chromatography–mass spectrometry (GC–MS). The suite of C₄ grasses allowed generalization of lignophenolic effects across two lignocellulosic bioconversion pathways: anaerobic digestion (AD) for methane production and liquid hot water pretreatment followed by enzymatic hydrolysis for ethanol production. Principal components analysis and simple linear statistical models showed ferulic acid (FER), syringaldehyde (SYR), and vanillin (VAN) ratios related to both bioconversion processes. Though methane production during AD was not well explained by linear models, more than 80% of variance across enzymatic breakdown of biomass during hydrolysis and ethanol production could be explained by FER, SYR, and VAN concentrations.