Green synthesis of yeast cell wall-derived carbon quantum dots with multiple biological activities

Hypothesis

Yeast cell walls are a sustainable biomass source containing carbon and other elements like phosphorus. Converting cell walls into valuable nanomaterials like carbon quantum dots (CQDs) is of interest.

Experiments

Cell walls from Saccharomyces cerevisiae were hydrothermally treated in 0.5 M H2SO4 to produce CQDs. Multiple analytical techniques were utilized to confirm phosphorus-doping (P-CQDs), characterize the fluorescence properties, determine quantum yield, and evaluate the sensing, antimicrobial, photocatalytic, and antioxidant capacities.

Findings

A successful synthesis of P-CQDs was achieved with strong blue fluorescence under UV excitation, 19 % quantum yield, and excellent stability. The P-CQDs showed sensitive fluorescence quenching in response to ferric ions with a 201 nM detection limit. Antibacterial effects against Escherichia coli and Staphylococcus aureus were demonstrated. P-CQDs also exhibited dye degradation under sunlight and antioxidant activity. So, the prepared P-CQDs displayed promising multifunctional capabilities for metal ion detection, disinfection, and environmental remediation. Further research is required to fully realize and implement the multifunctional potential of P-CQDs in real-world applications.

Assessment of mycotoxin sequestration efficacy in Saccharomyces cerevisiae by-products cultured in wheat bran and whey protein medium

Mycotoxins are metabolic products of fungi found in feed for farm animals and pose a major threat to food safety due to their adverse health effects. The development of strategies to reduce their bioavailability is crucial. In this context, the cell wall components of Saccharomyces cerevisiae (YCW), especially β-D-glucans and Mannan-oligosaccharide, have been recognized as potent mycotoxin binders. The objective of this research was to develop a novel culture medium to increase the biomass yield of S. cerevisiae and optimize cell disruption by stepwise physical lysis and hydrolytic preconditioning. This process resulted in a yield of approximately 56% reducing saccharides and 28.54% protein. Subsequently, the β-glucan was extracted after cell wall sequestration. The isolated YCW and extracted β-glucan were characterized both individually and synergistically to evaluate their antibacterial properties and analyze their Fourier transform infrared (FTIR) spectra. In vitro evaluation of antibacterial activity revealed that a concentration greater than 250 μg/mL of YCW-β-glucan blend significantly inhibited the growth of Gram-negative bacteria. In addition, this blend showed good adsorption of various mycotoxins, including Aflatoxin B1, Ochratoxin A, and Zearalenone, the latter of which exhibited a remarkable adsorption rate of 80.85%. This study highlights the promising potential of a combination of YCW and β-glucan as a robust strategy to address the pervasive problem of mycotoxin contamination in feed.