Sustainable green strategy for recovery of glucose from end-of-life euro banknotes

Usually, Euro banknotes are made from cotton substrates and their waste is disposed of in landfill or is incinerated. In order to valorize the end-of-life euro banknotes (ELEBs), the substrates were used in this research for cellulase production via submerged fungal fermentation (SFF), and the resultant fungal cellulase w s used in ELEBs hydrolysis process for extraction of glucose. The experiments were started by exposing the ELEBs to different types of pretreatments, including milling process, alkali (NaOH/urea solution), and acid leaching to remove any contamination (e.g. dyes) and to decrease the crystallinity of cellulose (the main element in cotton substrate) thus increasing the degradation rate during the fermentation process. The effect of pretreatments on the morphology and chemical composition of ELEBs was observed using Scanning Electron Microscope and Energy Dispersive Spectrometry. Afterwards, Trichoderma reesei-DSM76 was used for cellulase production from the treated ELEBs with high cellulase activity (12.97 FPU/g). The resultant cellulase was upscaled in a bioreactor and used in ELEBs hydrolysis. Finally, the results showed that the optimized pretreatment methods (milling followed by leaching process) significantly improved the cellulase activity and glucose recovery, which was estimated by 96%. According to the obtained results, the developed strategy has a great potential for conversion of ELEBs into a glucose product that could be used in biofuels and bioplastics applications.

Antifungal activity of styrylpyridinium compounds against Candida albicans

We synthesized a set of 13 new and earlier described styrylpyridinium compounds (N-alkyl styrylpyridinium salts with bromide or tosylate anions) in order to evaluate antifungal activity against C. albicans cells, to assay the possible synergism with fluconazole, and to estimate cytotoxicity to mammalian cells. All compounds were synthesized according to a well-known two-step procedure involving alkylation of γ-picoline with appropriate alkyl bromide and further condensation with substituted benzaldehyde. Compounds with long N-alkyl chains (C₁₈ H₃₇ -C₂₀ H₄₁ ) had no antifungal activity against the cells of all tested C. albicans strains. Other styrylpyridinium compounds were able to inhibit yeast growth at the concentrations of 0.06-16 μg/ml. At fungicidal concentrations, the compound with the CN- group was least toxic to mammalian cells, showed the most effective synergism with fluconazole, and only slightly inhibited the respiration of C. albicans. The compound with the 4'-diethylamino group exhibited the strongest fungicidal properties and effectively blocked the respiration of C. albicans cells. However, toxicity to mammalian cells was also high. Summarizing, the results of our study indicate that styrylpyridinium compounds are promising candidates in the development of new antifungal drugs.