Transcriptomic and metabolomic correlation analysis: effect of initial SO2 addition on higher alcohol synthesis in Saccharomyces cerevisiae and identification of key regulatory genes.

Introduction: Higher alcohols are volatile compounds produced during alcoholic fermentation that affect the quality and safety of the final product. This study used a correlation analysis of transcriptomics and metabolomics to study the impact of the initial addition of SO2 (30, 60, and 90 mg/L) on the synthesis of higher alcohols in Saccharomyces cerevisiae EC1118a and to identify key genes and metabolic pathways involved in their metabolism. Methods: Transcriptomics and metabolomics correlation analyses were performed and differentially expressed genes (DEGs) and differential metabolites were identified. Single-gene knockouts for targeting genes of important pathways were generated to study the roles of key genes involved in the regulation of higher alcohol production. Results: We found that, as the SO2 concentration increased, the production of total higher alcohols showed an overall trend of first increasing and then decreasing. Multi-omics correlation analysis revealed that the addition of SO2 affected carbon metabolism (ko01200), pyruvate metabolism (ko00620), glycolysis/gluconeogenesis (ko00010), the pentose phosphate pathway (ko00030), and other metabolic pathways, thereby changing the precursor substances. The availability of SO2 indirectly affects the formation of higher alcohols. In addition, excessive SO2 affected the growth of the strain, leading to the emergence of a lag phase. We screened the ten most likely genes and constructed recombinant strains to evaluate the impact of each gene on the formation of higher alcohols. The results showed that ADH4, SER33, and GDH2 are important genes of alcohol metabolism in S. cerevisiae. The isoamyl alcohol content of the EC1118a-ADH4 strain decreased by 21.003%; The isobutanol content of the EC1118a-SER33 strain was reduced by 71.346%; and the 2-phenylethanol content of EC1118a-GDH2 strain was reduced by 25.198%. Conclusion: This study lays a theoretical foundation for investigating the mechanism of initial addition of SO2 in the synthesis of higher alcohols in S. cerevisiae, uncovering DEGs and key metabolic pathways related to the synthesis of higher alcohols, and provides guidance for regulating these mechanisms.

[Investigation on the photoconductive properties of MEH-PPV/CdSe nanocomposite devices].

Photoconductive properties of the composite devices made up of cadmium selenide nanocrystals and polymer poly[2-methoxy-5-(2'-ethylhexyloxy-p-phenylenevinylene)] (MEH-PPV) were investigated. The photocurrent action spectrum for a nanocomposite device corresponded to the absorption of MEH-PPV and CdSe nanocrystals, indicating that the absorption of the CdSe nanocrystals and MEH-PPV contributed to the photocurrent. The photocurrent was attributed to the exciton dissociation and charge transfer between the interface of CdSe nanocrystals and MEH-PPV. The photocurrent action spectra of the nanocomposite device was wider than that of the pure MEH-PPV device, and the photocurrent was enhanced in comparison with the pure MEH-PPV device due to the introduction of CdSe nanocrystals.

[Study of water-sol core-shell CdSe/CdS quantum dots].

Water-sol core/shell CdSe/CdS quantum dots (QDs) were synthesized in aqueous solution by using mercapto-acetate acid as stabilizer. The UV-Vis absorption and emission spectra were studied. The size of the SdSe-core was about 2 nm estimated by absorption edge and X-ray powder diffraction(XRD). The structure was also characterized by X-ray photoelectron spectroscopy(XPS). The intensity of luminescence of the quantum dots was greatly enhanced after the surface was modified with CdS shell. Red shift of the peak was shown in both the emission and absorption spectra.