Proteomic Analysis of Saccharomyces cerevisiae Response to Oxidative Stress Mediated by Cocoa Polyphenols Extract

Cocoa presents cytotoxicity against melanoma cancer cell lines (A-375 e B16-F10) and improves chemotherapy activity by increasing oxidative stress

Melanoma frequently presents a poor chemotherapy response. In this scenario, investigations for new therapies are essential. Thus, cocoa is highlighted in this area since it presents many biological properties. This study investigated the anticarcinogenic activity of cocoa in melanoma cell lines (A-375 and B16-F10). Melanoma and fibroblast (HFF-1) cell lines were exposed to different concentrations of cocoa seeds (30 to 2000 ug/ml) at 24 and 72 h. Cocoa was also associated with paclitaxel IC50. We conducted viability, proliferation, and oxidative stress analyses. Our findings suggested that cocoa isolated, at almost all concentrations tested, was able to reduce viability and proliferation of B16-F10 cells and proliferation of A-375 cells via oxidative stress increasing. Also, cocoa caused no damage in fibroblast cells. Moreover, cocoa increased paclitaxel activity on A-375 by reducing cell proliferation and increasing oxidative stress. Therefore, the results highlight cocoa as a potent selective adjuvant anticancer agent against melanoma. PRACTICAL APPLICATIONS: In conclusion, more studies should be performed to deeply explore this remarkable action of cocoa as a an promising adjuvant to enhance chemotherapy.

Variation in glucose metabolism under acidified sodium nitrite mediated nitrosative stress in Saccharomyces cerevisiae

AIMS

The work aimed to understand the important changes during glucose metabolism in Saccharomyces cerevisiae under acidified sodium nitrite (ac.NaNO₂ ) mediated nitrosative stress.

METHODS AND RESULTS

Confocal microscopy and fluorescence-activated cell sorting analysis were performed to investigate the generation of reactive nitrogen and oxygen species, and redox homeostasis under nitrosative stress was also characterized. Quantitative PCR analysis revealed that the expression of ADH genes was upregulated under such condition, whereas the ACO2 gene was downregulated. Some of the enzymes of the tricarboxylic acid cycle were partially inhibited, whereas malate metabolism and alcoholic fermentation were increased under nitrosative stress. Kinetics of ethanol production was also characterized. A network analysis was conducted to validate our findings. In the presence of ac.NaNO₂ , in vitro protein tyrosine nitration formation was checked by western blotting using pure alcohol dehydrogenase and aconitase.

CONCLUSIONS

Alcoholic fermentation rate was increased under stress condition and this altered metabolism might be conjoined with the defence machinery to overcome the nitrosative stress.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first work of this kind where the role of metabolism under nitrosative stress has been characterized in S. cerevisiae and it will provide a base to develop an alternative method of industrial ethanol production.

Biological Processes Highlighted in Saccharomyces cerevisiae during the Sparkling Wines Elaboration

Sparkling wines elaboration has been studied by several research groups, but this is the first report on analysis of biological processes according to the Gene Ontology terms (GO terms) and related to proteins expressed by yeast cells during the second fermentation of sparkling wines. This work provides a comprehensive study of the most relevant biological processes in Saccharomyces cerevisiae P29, a sparkling wine strain, during the second fermentation under two conditions (without and with endogenous CO₂ overpressure) in the middle and the end of second fermentation. Consequently, a proteomic analysis with the OFFGEL fractionator and protein identification with LTQ Orbitrap XL coupled to HPLC were performed. The classification of biological processes was carried out using the tools provided by the Saccharomyces Genome Database. Results indicate that a greater number of biological processes were identified under condition without CO₂ overpressure and in the middle of the fermentation versus the end of the second fermentation. The biological processes highlighted under condition without CO₂ overpressure in the middle of the fermentation were involved in the carbohydrate and lipid metabolic processes and catabolic and biosynthetic processes. However, under CO₂ overpressure, specific protein expression in response to stress, transport, translation, and chromosome organization and specific processes were not found. At the end of fermentation, there were higher specific processes under condition without CO₂ overpressure; most were related to cell division, growth, biosynthetic process, and gene transcription resulting in increased cell viability in this condition. Under CO₂ overpressure condition, the most representative processes were related to translation as tRNA metabolic process, chromosome organization, mRNA processing, ribosome biogenesis, and ribonucleoprotein complex assembly, probably in response to the stress caused by the hard fermentation conditions. Therefore, a broader knowledge of the adaptation of the yeast, and its behavior under typical conditions to produce sparkling wine, might improve and favor the wine industry and the selection of yeast for obtaining a high-quality wine.

Functional Biodiversity of Yeasts Isolated from Colombian Fermented and Dry Cocoa Beans

Yeasts play an important role in the cocoa fermentation process. Although the most relevant function is the degradation of sugars and the production of ethanol, there is little understanding of the enzyme activities and attributes that allow them to survive even after drying. The present study explored the functional biodiversity of yeasts associated with Criollo Colombian cocoa fermented beans, able to survive after drying. Twelve species belonging to 10 genera of osmo-, acid-, thermo-, and desiccation-tolerant yeasts were isolated and identified from fermented and dry cocoa beans, with Pichia kudriavzevii and Saccharomyces cerevisiae standing out as the most frequent. For the first time, we reported the presence of Zygosaccharomyces bisporus in cocoa fermented beans. It was found that resistance to desiccation is related to the different degradation capacities of fermentation substrates, which suggests that associative relationships may exist between the different yeast species and their degradation products. Besides, the increased thermotolerance of some species was related to the presence of polyphenols in the medium, which might play a fundamental role in shaping the microbial community composition.