The Use of Cellobiose and Fructooligosaccharide on Growth and Stability of <i>Bifidobacterium infantis</i>in Fermented Milk

The effects of cellobiose, fructooligosaccharide and their combination on fermentation of skim milk by probiotic Bifidobacterium infantis were evaluated using mean doubling time as a parameter for sustaining growth. The lowest mean doubling time was observed for 2% cellobiose, followed by a combination of 2% fructooligosaccharide (FOS) with 2% cellobiose, while during storage at 4℃ for 4 weeks of fermented milk, no significant differences were observed between fermented milk supplemented with 2% cellobiose and 2% FOS. The highest viability retention during storage was observed for the combination of the two prebiotics, cellobiose and FOS. The results indicate that, in milk supplemented with cellobiose or a combination of cellobiose and FOS, Bifidobacterium infantis remain viable during 4 weeks of storage, suggesting the usefulness of cellobiose as a prebiotic ingredient in fermented products involving bifidobacteria.

Simultaneous formation of sorbitol and gluconic acid from cellobiose using carbon-supported ruthenium catalysts

A carbon-supported Ru catalyst, Ru/BP2000, is able to simultaneously convert cellobiose into sorbitol and gluconic acid. This reaction occurs as the result of hydrolytic disproportionation in water at 393 K under an Ar atmosphere, without bases or sacrificial reagents. In-situ XANES measurements suggest that the active Ru species involved is composed of partially oxidized Ru metal.

Synthesis of Propyl-Sulfonic Acid-Functionalized Nanoparticles as Catalysts for Cellobiose Hydrolysis

Functionalization of silica surfaces using organo-silanes is highly sensitive to reaction conditions. Silica-coated nanoparticles were functionalized with propyl-sulfonic acid groups (PS) under different synthesis conditions including, various solvents (Ethanol, methanol, acetonitrile, and toluene), water content in the reaction media (0% to 50%), 3-mercaptopropyl-trimethoxysilane concentration (MPTMS) (0.5% to 10%), and reaction time (6 to 16 h). Size of the PS-nanoparticles was determined by TEM and varied from 3.5 to 20.3 nm with sulfur load. Elemental analysis revealed sulfur contents from 0.8% to 22%. FTIR analysis showed increased C-H band intensities with increasing sulfur content of PS-nanoparticles. Although PS-nanoparticles with sulfur loads under 3% did not improve the hydrolysis of cellobiose, PS acid-functionalized nanoparticles with about 6% S achieved 96.0% cellobiose conversion. The control experiment, without catalyst, converted 32.8% of the initial cellobiose. PS-nanoparticles with (6% - 8% S) were obtained using (0.5%) silane concentration and 15 - 16 h reaction time in ethanol.

Synergistic effects of cellobiose dehydrogenase and manganese-dependent peroxidases during lignin degradation

The synergistic effects of cellobiose dehydro-genase (CDH) and manganese-dependent peroxidases (MnP) on the degradation of kraft pulp cellulolytic enzyme lignin (CEL) were investigated. Addition of CDH significantly increased the amount of water-soluble products reduced from CEL by MnP. CDH facilitated the reduction of the contents of methoxyl, carboxyl, phenolic hydroxyl and total hydroxyl groups of CEL by MnP. 1H-NMR analysis showed that addition of CDH also decreased further the amount of protons of CEL degraded by MnP. The results proved for the first time that CDH could promote degradation of lignin by MnP and suggest that CDH could not only promote degradation of cellulose but also is an important part of the lignin biodeg-radation system.

Mechanism of cellobiose inhibition in cellulose hydrolysis by cellobiohydrolase

An experimental study of cellobiose inhibition in cellulose hydrolysis by synergism of cellobiohydrolyse I and endoglucanase I is presented. Cellobiose is the structural unit of cellulose molecules and also the main product in enzymatic hydrolysis of cellulose. It has been identified that cellobiose can strongly inhibit hydrolysis reaction of cellulase, whereas it has no effect on the adsorption of cellulase on cellulose surface. The experimental data of FT-IR spectra, fluorescence spectrum and circular dichroism suggested that cellobiose can be combined with tryptophan residue located near the active site of cellobiohydrolase and then form steric hindrance, which prevents cellulose molecule chains from diffusing into active site of cellulase. In addition, the molecular conformation of cellobiohydrolase changes after cellobiose binding, which also causes most of the non-productive adsorption. Under these conditions, microfibrils cannot be separated from cellulose chains, thus further hydrolysis of cellulose can hardly proceed.

Comparative study of microwave-assisted versus conventional heated reactions of biomass conversion into levulinic acid over hierarchical Mn_(3)O_(4)/ZSM-5 zeolite catalysts

Conversion of delignified cellulose from rice husk biomass,and model compounds of cellobiose and glucose to levulinic acid(LA)over hierarchical Mn_(3)O_(4)/ZSM-5 catalyst was carried out using a household microwave method,and then compared to the established conventional thermos-reaction method.The hierarchical ZSM-5 was prepared using a double template method,aiming for micro and mesoporous systems developed in the structure.The as-prepared ZSM-5 were modified with Mn3O4 through incipient wetness impregnation with Mn2+solution followed by calcination at 550℃.The catalysts were characterized using various techniques such as powder XRD,SEM,BET,AAS,and FT-IR which indicated the hierarchical structure of MFI zeolite(Si/Al of 30-34)with Mn loading of 2.14 wt%.The conversion products were analyzed using HPLC,1H NMR,and 13C NMR instruments.The microwave-assisted reaction using 600 W for 180 s using delignified cellulose,cellobiose,and glucose gave conversion of 37.27%,46.35%,and 54.29%,respectively which is close to the conversion given by the conventional reaction carried out at 130◦C for 4 h(36.75%,55.62%,and 60.9%,respectively).Interestingly,the LA yield from the microwave-assisted reaction(4.33%,6.12%,and 9.57%)is higher than the yield from the conventional reaction,which only produced 5.2%,4.88%,and 6.93%respectively.The microwaveassisted method is also shown to give less by-products compared to the thermochemical reaction.Therefore,it could be considered an alternative method for converting cellulose to LA.

Understanding cellulose dissolution： effect of the cation and anion structure of ionic liquids on the solubility of cellulose

The effect of ionic liquids(ILs) on the solubility of cellulose was investigated by changing their anions and cations. The structural variation included 11 kinds of cations in combination with 4 kinds of anions. The interaction between the IL and cellobiose, the repeating unit of cellulose, was clarified through nuclear magnetic resonance(NMR) spectroscopy. The reason for different dissolving capabilities of various ILs was revealed. The hydrogen bonding interaction between the IL and hydroxyl was the major force for cellulose dissolution. Both the anion and cation in the IL formed hydrogen bonds with cellulose. Anions associated with hydrogen atoms of hydroxyls, and cations favored the formation of hydrogen bonds with oxygen atoms of hydroxyls by utilizing activated protons in imidazolium ring. Weakening of either the hydrogen bonding interaction between the anion and cellulose, or that between the cation and cellulose, or both, decreases the capability of ILs to dissolve cellulose.