Carbohydrate and lignin partitioning in switchgrass biomass (Panicum virgatum L.) as a bioenergy feedstock

Abstract

Approaching switchgrass (Panicum virgatum L.) as a multifunctional energy plant, it is important to comprehensively study the composition and partitioning of organic substances in the biomass. The character of carbohydrates and lignin concentration variation was assessed in switchgrass biomass cut at two maturity stages (heading and seed filling) in the first and second harvest years. Quality components partitioning in the biomass of aboveground plant parts was examined in leaves, stems and panicles of the most productive switchgrass accessions cut at seed filling. The concentrations of lignocellulose (NDF), cellulose (Cel), sum of structural carbohydrates (holocellulose -HoCel), sum of nonstructural and structural carbohydrates (ΣCH 2 O) and lignin in switchgrass biomass of both plant development stages in the second harvest year were significantly higher, whereas an average hemicellulose (HCel) concentration was significantly lower compared with the respective parameters in the first harvest year. The concentrations of nonstructural carbohydrates (NSC) and their individual fractions (water soluble carbohydrates (WSC) and starch) in biomass were similar both in the first and second harvest years. The concentrations of NDF, Cel, HoCel and ΣCH 2 O and particularly lignin at seed filling were significantly higher compared with the respective data at heading in both harvest years. High lignin concentration (105 g kg -1 dry matter (DM)) in switchgrass biomass at seed filling in the second harvest year showed its great suitability for solid biofuel production. Considerable amount of ΣCH 2 O (693-742 g kg -1 DM) indicated that switchgrass biomass at this stage fits for the second-generation bioethanol production. At heading, switchgrass in the second harvest year produced quite a high NSC yield (an average 28.4 g plant -1 ) and low lignin output (an average 19.3 g plant -1 ), which is a favourable feature of feedstock for biogas production, biomass at seed filling is less suitable for that than at heading. Switchgrass plant part significantly (P < 0.01) affected the concentration of all biomass quality attributes tested, but did not affect HCel concentration. Accessions' DM yield correlated positively with NDF (r = 0.781, P < 0.05), Cel (r = 0.882, P < 0.01) and lignin (r = 0.517) and negatively with WSC and NSC (r = −0.982, −0.959; P < 0.01).

Characterization of Chemically Activated Carbons Prepared from Miscanthus and Switchgrass Biomass

“…Here, holocellulose content in miscanthus corresponded with data recorded for plantations in the temperate climate zone [19,32,33]. Lower holocellulose contents in switchgrass biomass were also observed earlier [34,35]. Regarding cellulose, the main holocellulose component, the determined contents for M. × giganteus, M. sacchariflorus and M. sinensis (Table 2), also fell within the ranges for these species cultivated in other temperate regions [19,32,33,36,37].…”

Chlorophyll values as a measure of genetic variation of switchgrass (Panicum virgatum L.) populations under cool temperate climate conditions

“…Switchgrass has a disadvantage in yielding capability during the first harvest years due to the allocation of a large amount of energy for developing a strong root system (McLaughlin, Kszos, 2005). A similar tendency was obtained in Northwest and Southern Europe (Elbersen, 2001;Butkutė et al, 2013). However, this trend had no relations with chlorophyll content dynamics presented in this paper.…”

“…Switchgrass investigations under cool temperate climate conditions are scarce. Initial research on switchgrass showed promising results of this grass as solid biofuel and biogas stock under Lithuanian temperate climate conditions (Butkutė et al, 2013).…”

Ethanol production from cassava stem using Saccharomyces cerevisiae TISTR 5339 through simultaneous saccharification and fermentation

“…Aside from the cassava stem, other lignocellulose residues were also reported ( Table 3). The cellulose content from the cassava stem was compared to other reported cellulose content such as 44% for Acacia mangium and 42% for Acacia hybrid (Boondaeng et al, 2015), 26-43% for bamboo (Sánchez, 2009), 42-45% for corn cob (Kuhad and Singh, 1993;Prasad et al, 2007;Liu et al, 2010), 20-25% for hardwood (McKendry, 2002), 43% for the empty fruit bunch of oil palm (Garcia-Nunez et al, 2016), 28-36% for rice straw (Chen et al, 2008;Saini et al, 2015), 27-30% for softwood (McKendry, 2002), 42-48% for sugarcane bagasse (Kuhad and Singh, 1993;Rocha et al, 2015;Saini et al, 2015) and 5-34% for switch grass (Butkute et al, 2013;Saini et al, 2015). These figures indicated that cassava stem has a high potential to be used as a feedstock in bioconversion processes for ethanol fermentation, especially as it can be obtained in large quantities from local growers.…”