Quantitative 13C MultiCP solid-state NMR as a tool for evaluation of cellulose crystallinity index measured directly inside sugarcane biomass

作者：Oigres Daniel Bernardinelli, Marisa Aparecida de Lima, Camila A. Rezende, Igor Polikarpov, Eduardo R. deAzevedo · 发表于：Biotechnology for Biofuels · 年份：2015 · DOI：10.1186/s13068-015-0292-1 · 被引用次数：112 · 研究领域：Advanced Cellulose Research Studies、Advanced NMR Techniques and Applications、NMR spectroscopy and applications

BACKGROUND: The crystallinity index (CI) is often associated with changes in cellulose structure after biological and physicochemical pretreatments. While some results obtained with lignocellulosic biomass demonstrate a progressive increase in the CI as a function of pretreatments, it is also shown that the CI can significantly vary depending on the choice of the measurement method. Besides, the influence of the CI on the recalcitrance of biomass has been controversial for a long time, but the most recent results tend to point out that the efficiency of pretreatments in reducing the recalcitrance is not clearly correlated with the decrease of the CI. Much of this controversy is somewhat associated with the inability to distinguish between the CI of the cellulose inside the biomass and the CI of the full biomass, which contains other amorphous components such as lignin and hemicellulose. RESULTS: Cross polarization by multiple contact periods (Multi-CP) method was used to obtain quantitative (13)C solid-state nuclear magnetic resonance (ssNMR) spectra of sugarcane bagasse biomass submitted to two-step pretreatments and/or enzymatic hydrolysis. By comparing the dipolar filtered Multi-CP (13)C NMR spectra of untreated bagasse samples with those of samples submitted to acid pretreatment, we show that a 1% H2SO4-assisted pretreatment was very effective in removing practically all the hemicellulose signals. This led us to propose a spectral editing procedure based on the subtractio...