Browsing by Author "Lopes, Ana"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
- Carnosic acid production from sugarcane syrup by engineered yeast in fed-batch fermentationPublication . Carsanba, Erdem; Fernandes, Sara; Beato, Felipe; Carvalho, Luís Carlos; Pintado, Ana; Lopes, Ana; Ribeiro, Mónica; Leal, Tânia; Pintado, Manuela; Oliveira, CarlaPhenolic diterpene carnosic acid (CA) is widely used in the food, nutritional health, and cosmetic industries due to its antioxidative and antimicrobial properties. This work aimed to overproduce CA in Saccharomyces cerevisiae from sugarcane syrup in fed-batch 2 L bioreactor fermentation. A geranylgeranyl diphosphate (GGPP)-producing strain modified with genes encoding the enzymes copalyl diphosphate synthase (Pv.CPS), miltiradiene synthase (Ro.KSL2), hydroxy ferruginol synthase (Ro.HFS), CA synthase (Ro.CYP76AK8), CYP reductase (At.ATR1), and transketolase (TKL1) was used. Lowering the feed rate from 12–26 g/L/h to 7–8 g/L/h, and the use of a dynamic dissolved oxygen (DO) trigger (min. 10%, max. 40%, threshold 70%) instead of a DO trigger of 30%, enhanced CA production by 27%. As a result, the highest CA titer ever reported to date, 191.4 mg/L, was obtained in 4-day fermentation. This study shows the feasibility of engineered yeast to produce CA from the sustainable feedstock sugarcane syrup.
- L'histoire singulière d'Angelina de Sousa Mendes en FrancePublication . Lopes, AnaNão é de admirar que Angelina de Sousa Mendes, mulher de Aristides de Sousa Mendes, um herói intemporal, tenha permanecido na invisibilidade. Os actos desinteressados não puderam ser bem avaliados principalmente depois do funesto destino deste casal e dos seus filhos, em Portugal. Com efeito, Angelina não se limitou a cumprir os papéis tradicionais femininos. Esta multifacetada senhora ultrapassou-os de longe ao aderir a causas humanitárias e ao assumir uma missão e uma actividade perigosas em tempo de guerra. Sai agora da invisibilidade e do esquecimento mostrando como está bem para além do seu tempo.
- Peptide extract from spent yeast improves resistance of Saccharomyces cerevisiae to oxidative stressPublication . Lopes, Ana; Azevedo-Silva, João; Carsanba, Erdem; Pintado, Manuela; Oliveira, Ana Sofia; Ferreira, Carlos; Pereira, Joana Odila; Carvalho, Ana P.; Oliveira, CarlaYeast cells face various stress factors during industrial fermentations, since they are exposed to harsh environmental conditions, which may impair biomolecules productivity and yield. In this work, the use of an antioxidant peptide extract obtained from industrial spent yeast was explored as supplement for Saccharomyces cerevisiae fermentation to prevent a common bottleneck: oxidative stress. For that, a recombinant yeast strain, producer of β-farnesene, was firstly incubated with 0.5 and 0.7 g/L peptide extract, in the presence and absence of hydrogen peroxide (an oxidative stress inducer), for 1–5 h, and then assayed for intracellular reactive oxygen species, and growth ability in agar spot assays. Results showed that under 2 mM H2O2, the peptide extract could improve cells growth and reduce reactive oxygen species production. Therefore, this antioxidant effect was further evaluated in shake-flasks and 2-L bioreactor batch fermentations. Peptide extract (0.7 g/L) was able to increase yeast resistance to the oxidative stress promoted by 2 mM H2O2, by reducing reactive oxygen species levels between 1.2- and 1.7-fold in bioreactor and between 1.2- and 3-fold in shake-flask fermentations. Moreover, improvements on yeast cell density of up to 1.5-fold and 2-fold, and on biomolecule concentration of up to 1.6-fold and 2.8-fold, in bioreactor and shake-flasks, respectively, were obtained. Thus, culture medium supplementation with antioxidant peptide extracted from industrial spent yeast is a promising strategy to improve fermentation performance while valuing biomass waste. This valorization can promote a sustainable and eco-friendly solution for the biotechnology industry by the implementation of a circular economy model.