Pectin is a complex dietary fiber and a prebiotic. To investigate pectin-induced changes in the gut microbiome and their effects on the short chain fatty acids (SCFAs) production, we performed in vitro pectin fermentation using the feces of three Korean donors. The pectin degradations in all three donors were observed. While the donors displayed differences in baseline gut microbiota composition, commonly increased bacteria after pectin fermentation included Lachnospira, Dorea, Clostridium, and Sutterella. Regarding SCFAs, acetate levels rapidly increased with incubation with pectin, and butyrate levels also increased after 6 h of incubation. The results suggest that pectin fermentation increases bacterial species belonging to Clostridium cluster XIV (Lachnospira, Dorea, and Clostridium), with Lachnospira displaying the greatest increase. The results also confirm that pectin fermentation leads to the production of acetate and butyrate.Electronic supplementary materialThe online version of this article (10.1186/s13568-018-0629-9) contains supplementary material, which is available to authorized users.

Using grand canonical Monte Carlo (GCMC) simulations with our recently developed first-principles-based force fields, we report the effects of porosity and interpenetration on the CO2 uptake in 14 prototypical MOFs (metal organic frameworks). The maximum CO2 capacity for both total and excess uptakes at high pressures (e.g., 50 bar) correlates well with the pore volume of MOFs and zeolitic imidazolate frameworks, rather than the surface area, which agrees well with the experimental results. The interpenetration between MOFs leads to smaller pore volume (higher density) lowering the maximum CO2 uptake at high pressures. However, the interpenetrating MOFs produce new CO2 adsorption sites with high binding affinity (approximately twice that of noninterpenetrating MOFs), such as shared spaces created by two organic linkers of adjacent MOFs, enhancing CO2 uptake at low pressures (e.g., 2 bar). For H2 uptake at 298 K, on the other hand, the interpenetration does not provide positive effects. For these reasons, the interpenetration of MOFs remarkably enhances the selectivity of CO2 over H2, by more than 3 times that of noninterpenetrating MOFs. These results also show that smaller pores in MOFs are, indeed, advantageous for the CO2/H2 separation.

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The transglycosylation activity of amylosucrase (ASase) has received significant attention owing to its use of an inexpensive donor, sucrose, and broad acceptor specificity, including glycone and aglycone compounds. The transglycosylation reaction of recombinant ASase from (DRpAS) was investigated using various phenolic compounds, and quercetin-3--rutinoside (rutin) was found to be the most suitable acceptor molecule used by DRpAS. Two amino acid residues in DRpAS variants (DRpAS Q299K and DRpAS Q299R), assumed to be involved in acceptor binding, were constructed by site-directed mutagenesis. Intriguingly, DRpAS Q299K and DRpAS Q299R produced 10-fold and 4-fold higher levels of rutin transglycosylation product than did the wild-type (WT) DRpAS, respectively. According to in silico molecular docking analysis, the lysine residue at position 299 in the mutants enables rutin to more easily position inside the active pocket of the mutant enzyme than in that of the WT, due to conformational changes in loop 4.