Enzymatic transformations of cellulose assessed by quantitative high‐throughput fourier transform infrared spectroscopy (QHT‐FTIR)

Abstract

Enzymatic hydrolysis of bacterial microcrystalline cellulose was performed with the thermophile enzyme system of Thermobifida fusca Cel5A (a classical endocellulase), Cel6B (a classical exocellulase), Cel9A (a processive endoglucanase), and a synergistic mixture of endo- and exocellulases. Different concentrations of enzymes were used to vary the extent of hydrolysis. Following standardization, the concentration of cellulose was directly correlated to the absorbance of the cellulose signals. Crystallinity indexes (Lateral Order Index (LOI), Total Crystallinity Index, Hydrogen Bonding Index), allomorphic composition, conversion of specific atomic bonds (including the β-glucosidic bonds) were extracted from the spectral data obtained by QHT-FTIR. By quantifying the disruption of the H-bonding in complement to the sugar production, a more dynamic and complex picture of the role of cellulases in the hydrolysis of cellulose was demonstrated. The disruption of the H-bonding within the cellulose matrix appears as a quantifiable activity of the enzymes which was not correlated with the production of sugars in solution. The results also demonstrate that Cel9A activities from the cellulose transformation standpoint were partially similar to the activities of the synergistic mixture. In addition, Cel9A preferentially degraded the I(α) fraction of the crystalline cellulose while the Cel5A and Cel6B synergistic mixture preferentially degraded the I(β) fraction.

Transformation of Miscanthus and Sorghum cellulose during methane fermentation

“…The lateral order index (LOI) is correlated with the overall degree of the ordered structure in the cellulose (Poletto et al 2014;Corgié et al 2011;Carrilo et al 2004). The cellulose LOI from unfermented materials ranged from 1.966 to 2.119 and after fermentation it was a bit higher and ranged from 1.974 to 2.360 (Table 4).…”

Structural Characteristics and Thermal Properties of Native Cellulose

“…The band at 1642 cm -1 is associated with adsorbed water in cellulose and probably some hemicelluloses [17,[37][38]. The bands at 1430, 1370, 1335 and 1320 cm -1 are attributed to CH2 symmetric bending, CH bending, in-plane OH bending, CH2 rocking vibration, respectively [17,[38][39], and the bands at 1162, 1111, 1057, 1033, 898 cm -1 are assigned to asymmetric C-O-C bridge stretching, anhydroglucose ring asymmetric stretching, C-O stretching, in-plane C-H deformation and C-H deformation of cellulose, respectively [17,[38][39][40][41]. The total crystalline index (TCI), lateral order index (LOI), hydrogen bond energy (EH), and hydrogen bond intensity (HBI) were calculated from the spectra obtained from FTIR spectroscopy.…”

Materials produced from plant biomass: part II: evaluation of crystallinity and degradation kinetics of cellulose

“…The band at 1642 cm -1 is associated with adsorbed water in cellulose 19,22,23 . The bands at 1430, 1370, 1335 and 1320 cm -1 are attributed to CH 2 symmetric bending, CH bending, OH in plane bending, CH 2 rocking vibration, respectively [21][22][23] , and the bands at 1162, 1111, 1057, 1033, 898 cm -1 are assigned to asymmetric C-O-C bridge stretching, the anhydroglucose ring asymmetric stretching, C-O stretching, C-H in plane deformation, C-H deformation of cellulose, respectively [21][22][23][24]26 . On the other hand, the peaks for xylan from hemicelluloses are derived from molecular vibrations in the uronic acids at 1730 and 1600 cm -1 [28] .…”

“…The TCI is proportional to the crystallinity degree of cellulose 20 and LOI is correlated to the overall degree of order in cellulose 22,26 . Based on this fact, the CPT showed the highest TCI and LOI value indicating highest degree of crystallinity and more ordered cellulose structure than the CEG.…”

“…Several techniques as X-ray diffraction and FTIR spectroscopy were used to evaluate the wood and cellulose crystallinity 5,7,8,9,10,12 . However, FTIR spectroscopy has been used as a simple technique for obtaining rapid information about the structure of cellulose and chemical changes taking place in cellulose due to various treatments 10,21,22,[25][26][27] . As mentioned earlier, the crystalline structure of cellulose affects the physical, mechanical and thermal properties of cellulose fibers.…”