Suchergebnisse

The polyphenol resveratrol (3,5,4-trihydroxystilbene) is a well-known plant secondary metabolite, commonly used as a medical ingredient and a nutritional supplement. Due to its health-promoting properties, the demand for resveratrol is expected to continue growing. This stilbene can be found in different plants, including grapes, berries (blackberries, blueberries and raspberries), peanuts and their derived food products, such as wine and juice. The commercially available resveratrol is usually extracted from plants, however this procedure has several drawbacks such as low concentration of the product of interest, seasonal variation, risk of plant diseases and product stability. Alternative production processes are being developed to enable the biotechnological production of resveratrol by genetically engineering several microbial hosts, such as Escherichia coli, Corynebacterium glutamicum, Lactococcus lactis, among others. However, these bacterial species are not able to naturally synthetize resveratrol and therefore genetic modifications have been performed. The application of emerging metabolic engineering offers new possibilities for strain and process optimization. This mini-review will discuss the recent progress on resveratrol biosynthesis in engineered bacteria, with a special focus on the metabolic engineering modifications, as well as the optimization of the production process. These strategies offer new tools to overcome the limitations and challenges for microbial production of resveratrol in industry. ; We would like to thank the European Union Framework Program 7 "BacHBerry" (http://www.bachb erry.eu), Project No. FP7-613793 for financial support, the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469 unit, COMPETE 2020 (POCI-01-0145FEDER-006684) and BiotecNorte operation (NORTE-01-0145FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. ...

BACKGROUND The growing interest in polyphenols has led to the design of industrial-scale processes able to produce them by fermentation and recover them in a more sustainable way. The goal of this work is to present two integrated approaches for the recovery of resveratrol, obtained through fermentation. The production of resveratrol using Corynebacterium glutamicum and its continuous removal using a hydrophobic resin is described. Batch production is compared with in situ product removal, where Amberlite XAD-7HP is either directly added to the medium (direct adsorption) or is present in an external column (external adsorption). RESULTS For both adsorption strategies tested, the amount of extracellular resveratrol increased from 75% to at least 90% of the total amount produced. However, lower total resveratrol concentrations were attained 3.6 and 2.2mg L-1, for the external and direct contact strategies, respectively, versus 5.3mg L-1 for batch experiments. CONCLUSIONS The proposed in situ removal strategies demonstrated the potential of increasing the excretion of resveratrol produced intracellularly. These process configurations may not only lead to a simpler downstream process design, but also to the avoidance of potential problems with the toxicity of polyphenols to the cells, especially when larger titers are obtained. © 2017 Society of Chemical Industry ; We would like to thank the European Union Framework Program 7 'BacHBerry' (www.bachberry.eu), Project No. FP7- 613793 for financial support, the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit, COMPETE 2020 (POCI-01- 0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145- FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. ...