Abstract
Forage grasses, such as Panicum maximum , are important
alternatives of lignocellulosic biomass for bioethanol production. Thus,
this study investigates whether future climate conditions could
influence P. maximum cell wall structure and hydrolytic
performance. A combined temperature-free air controlled and a free-air
carbon dioxide enrichment (Trop-T-FACE) facility was used to
investigated the isolated and combined effect of elevated atmospheric
CO2 concentration (eC) (600
μmol.mol-1) and elevated temperature (eT) by 2˚C more
than the ambient temperature, on cell wall composition, cellulose
crystallinity, accessibility, and hydrolysis yields. The elevated
temperature treatments (eT and eT+eC) exhibited the most pronounced
effects. Warming reduced starch content and crystallinity index (CI) of
cellulose while increased cellulose content. The fluorescent
protein-tagged carbohydrate-binding modules analysis demonstrated that
warming led to improvement in the total cellulose surface
exposure/accessibility in eT and eT+eC by 181% and 132%, respectively.
Consequently, glucan conversion yields were improved by 7.07 and 5.37%,
showing that warming led to lower recalcitrance in P. maximumbiomass, which positively affect its use in biorefineries. Therefore,
this work provides important information from an ecological and economic
point of view, and might assist in the selection of tropical forage
grasses efficiently adapted to climate changes with positive effect on
bioenergy production.
Key words: climate change, bioenergy, cell wall,
lignocellulosic biomass, enzymatic saccharification,
carbohydrate-binding modules.