Kookmin University

The transition from an economy reliant on fossil fuels to a sustainable bioeconomy that utilizes renewable biomass feedstock to produce chemicals, bioplastics, and biofuels is imperative. β-Glucosidase (BGL) is essential for hydrolyzing cellooligosaccharides in lignocellulosic biomass to generate glucose. During biomass degradation, glucose can inhibit or stimulate BGL activity. Accordingly, identifying and characterizing glucose-stimulated and glucose-tolerant BGL has become a major research focus in industrial BGL applications. In the current study, BGL Cba3 from Cellulomonas biazotea-a cellulose-degrading bacterium-(CbiCba3) demonstrated glucose-stimulated and glucose-tolerant properties. The hydrolase activity of CbiCba3 increased by 1.3-fold in the presence of 31.25 mM glucose and was maintained at glucose concentrations up to 500 mM. The crystal structure of glucose-bound CbiCba3 shows that the glucose molecule binds the glycone and gatekeeper regions. The occupancy of the glucose molecule in the gatekeeper region reduces the substrate-accessible entrance and induces conformational changes in the Gln295 and Val310 side chains, narrowing the substrate entrance. Mutagenesis studies revealed that glucose binding the gatekeeper region is responsible for glucose stimulation; this binding site of CbiCba3 is distinct from those previously reported for glucose-stimulated BGLs. Meanwhile, Trp323 and Asn176 in CbiCba3 form a narrow substrate-binding channel at the aglycone site associated with glucose tolerance. Although Asn176 is not conserved in other glucose-tolerant BGLs, their channel widths are similar. These results highlight the significant glucose-stimulated and glucose-tolerant properties of CbiCba3, providing valuable insights for BGL protein engineering to enhance enzyme activity for more efficient biotechnological applications.

This research aims to develop an antifungal packaging film to mitigate the quality deterioration of mass-produced bread for industrial purposes. Various antifungal agents were tested against four target fungi; Aspergillus niger, A. flavus, Penicillium corylophilum, and Neurospora sp.; commonly found in bread, to replace the commercial antifungal film. Among them, Cinnamomum cassia essential oil (CEO) exhibited strong antifungal activity, with MIC values below 100 ppm against all tested strains. We implemented the CEO-incorporated powder onto the multilayered packaging film and subsequent packaging trials were conducted on the industrial packaging machinery. Organoleptic analyses using electronic tongue and electronic nose revealed that the application of CEO maintained the bread's flavor and aroma throughout storage, implying the newly developed CEO-treated film was comparably preferred to the conventional material. Therefore, this investigation highlights the promising potential of CEO's effective antifungal agent to combat bread quality deterioration during distribution for industrial operations.

This study aims to develop a facile and efficient synthetic method utilizing iodine as a catalyst for the deoxygenative coupling of indolin-3-one derivatives with thiols. Reaction of indolin-3-ones with a range of alkane- and arenethiols with 3 mol% iodine in 2,2,2-trifluoroethanol at room temperature or 60 °C gave 3-alkylthio- or 3-arylthio-substituted indoles in 52–98% yields while reaction with arenethiols using 10 mol% iodine, 1.2 equiv sodium hydroxide in acetonitrile gave 2-(arylthio)indoline-3-ones in moderate yields. Hence, regioselective C–S bond formation, which is produced at the C2 or C3 position of indolin-3-one, was achieved, depending on the presence or absence of a base and, advantageously, without the need for a transition metal catalyst and additional synthetic steps.