The fully biobased polyhydroxyalkanoate (PHA) polymers provide interesting alternatives for petrochemical derived plastic materials. The mechanical properties of some PHAs, including the common poly(3-hydroxybutyrate) (PHB), are limited, but tunable by addition of other monomers into the polymer chain. In this study we present a precise synthetic biology method to adjust lactate monomer fraction of a polymer by controlling the monomer formation at gene expression level, independent of cultivation conditions. We used the modified doxycycline-based Tet-On approach to adjust the expression of the stereospecific D-lactate dehydrogenase gene () from to control D-lactic acid formation in yeast . The synthetic Tet-On transcription factor with a VP16 activation domain was continuously expressed and its binding to a synthetic promoter with eight transcription factor specific binding sites upstream of the gene was controlled with the doxycycline concentration in the media. The increase in doxycycline concentration correlated positively with expression, D-lactic acid production, poly(D-lactic acid) (PDLA) accumulation , and D-lactic acid content in the poly(D-lactate--3-hydroxybutyrate) P(LA-3HB) copolymer. We demonstrated that the D-lactic acid content of the P(LA-3HB) copolymer can be adjusted linearly from 6 mol% to 93 mol% in . These results highlight the power of controlling gene expression and monomer formation in the tuning of the polymer composition. In addition, we obtained 5.6% PDLA and 19% P(LA-3HB) of the cell dry weight (CDW), which are over two- and five-fold higher accumulation levels, respectively, than reported in the previous studies with yeast. We also compared two engineered PHA synthases and discovered that in the PHA synthase PhaC1437 produced P(LA-3HB) copolymers with lower D-lactic acid content, but with higher molecular weight, in comparison to the PHA synthase PhaC1Pre.
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http://dx.doi.org/10.1016/j.mec.2022.e00199 | DOI Listing |
Turk J Pediatr
December 2024
Department of Pathology, Faculty of Medicine, Hacettepe University, Ankara, Türkiye.
Background: Primary breast lymphoma is extremely rare and constitutes approximately 1% of all non-Hodgkin's lymphomas (NHL). Only 1-5% of them are Burkitt type. We present a case of childhood primary breast Burkitt lymphoma (BL).
View Article and Find Full Text PDFCurr Res Food Sci
December 2024
Translational Research Center in Gastrointestinal Disorders (TARGID), Department of Chronic Diseases and Metabolism, Medicine, KU Leuven, Leuven, Belgium.
Sourdough bread consumption has been associated with improved glucose and appetite regulation thanks to the presence of organic acids produced during fermentation of the flour-water mixture. We investigated the effects of whole meal sourdough bread (WSB) rich in lactic acid on energy intake, satiety, gastric emptying, glucose, and C-peptide response compared to whole meal yeast bread (WYB). Forty-four normal-weight participants (age: 30 ± 10 y; BMI: 23 ± 2 kg/m) participated in this double-blind, randomized cross-over trial, consisting of two study visits separated by one week.
View Article and Find Full Text PDFRSC Adv
January 2025
Adolphe Merkle Institute, University of Fribourg 1700 Fribourg Switzerland
β-Carotene (βC), a natural carotenoid, is the most important and effective vitamin A precursor, known also for its antioxidant properties. However, its poor water solubility, chemical instability, and low bioavailability limit its effectiveness as an orally delivered functional nutrient. Nanoparticle encapsulation improves βC's bioaccessibility by enhancing its stability and solubility.
View Article and Find Full Text PDFInt J Pharm X
June 2025
Department of Drug Sciences, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy.
Thermoplastic polymers provide a versatile platform to mimic various aspects of physiological extracellular matrix properties such as chemical composition, stiffness, and topography for use in cell and tissue engineering applications. In this review, we provide a brief overview of the most promising thermoplastic polymers, and in particular the thermoplastic polyesters, such as poly(lactic acid), poly(glycolic acid), and polycaprolactone, and the thermoplastic elastomers, such as polyurethanes, polyhydroxyalkanoates, and poly(butyl cyanoacrylate). A particular focus has been made on the synthesis processes, the processability and the biocompatibility.
View Article and Find Full Text PDFBMJ Open
December 2024
Rio Hortega, Valladolid University Hospital, Valladolid, Spain.
Objectives: Point-of-care testing available in prehospital settings requires the establishment of new medical decision points. The aim of the present work was to determine the cut-off of the lactate threshold that activates alert triggers for all-cause 2-day mortality.
Design: Multicentre, prospective, ambulance-based, observational study.
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