Browsing by Author "Grandfils, Christian"
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- Demonstration of the ability of the bacterial polysaccharide FucoPol to flocculate kaolin suspensionsPublication . Araújo, Diana; Concórdio-Reis, Patrícia; Marques, Ana C.; Sevrin, Chantal; Grandfils, Christian; Delgado Alves, VitorIn this study, the flocculation properties of FucoPol, a bacterial extracellular polysaccharide, were investigated. FucoPol is a high molecular weight polymer and negatively charged due to the presence of glucuronic acid and the acyl groups succinyl and pyruvyl. High flocculation rate values (>70%) were achieved with a low bioflocculant dosage of 1 mg/L, for pH values in the range 3–5 and temperature within 15–20°C. The bioflocculant was also shown to be stable after freezing/thawing and heating up to 100°C. Given the polymer’s anionic character, the size of flocs formed and their surface profile, bridging seems to be the main flocculation mechanism of FucoPol. This study demonstrated that FucoPol is a promising natural, biodegradable and biocompatible alternative to the currently used synthetic or inorganic hazardous products, with potential to be used as a novel flocculation agent in several applications, such as water treatment, food or mining. Further studies will involve evaluating the reduction of cation dosage on flocculation efficiency, as well as testing the applicability of FucoPol to flocculate different types of suspended solids, such as, for example, activated carbons, soil solids or yeast cells
- Preparation and characterization of films based on a natural P(3HB)/mcl-PHA blend obtained through the co-culture of Cupriavidus necator and Pseudomonas citronellolis in apple pulp wastePublication . Rebocho, Ana Teresa; Pereira, João R.; Neves, Luísa A.; Delgado Alves, Vitor; Sevrin, Chantal; Grandfils, Christian; Freitas, Filomena; Reis, Maria A.M.The co-culture of Cupriavidus necator DSM 428 and Pseudomonas citronellolis NRRL B-2504 was performed using apple pulp waste from the fruit processing industry as the sole carbon source to produce poly(3-hydroxybutyrate), P(3HB) and medium-chain length PHA, mcl-PHA, respectively. The polymers accumulated by both strains were extracted from the co-culture’s biomass, resulting in a natural blend that was composed of around 48 wt% P(3HB) and 52 wt% mcl-PHA, with an average molecular weight of 4.3 105 Da and a polydispersity index of 2.2. Two melting temperatures (Tm) were observed for the blend, 52 and 174 C, which correspond to the Tm of the mcl-PHA and P(3HB), respectively. P(3HB)/mcl-PHA blend films prepared by the solvent evaporation method had permeabilities to oxygen and carbon dioxide of 2.6 and 32 Barrer, respectively. The films were flexible and easily deformed, as demonstrated by their tensile strength at break of 1.47 0.07 MPa, with a deformation of 338 19% until breaking, associated with a Young modulus of 5.42 1.02 MPa. This study demonstrates for the first time the feasibility of using the co-culture of C. necator and P. citronellolis strains to obtain a natural blend of P(3HB)/mcl-PHA that can be processed into films suitable for applications ranging from commodity packaging products to high-value biomaterials
- Preparation and Characterization of Films Based on a Natural P(3HB)/mcl-PHA Blend Obtained through the Co-culture of Cupriavidus Necator and Pseudomonas Citronellolis in Apple Pulp WastePublication . Rebocho, Ana Teresa; Pereira, João R.; Neves, Luísa A.; Delgado Alves, Vitor; Sevrin, Chantal; Grandfils, Christian; Freitas, Filomena; Reis, Maria A.M.The co-culture of Cupriavidus necator DSM 428 and Pseudomonas citronellolis NRRL B-2504 was performed using apple pulp waste from the fruit processing industry as the sole carbon source to produce poly(3-hydroxybutyrate), P(3HB) and medium-chain length PHA, mcl-PHA, respectively. The polymers accumulated by both strains were extracted from the co-culture’s biomass, resulting in a natural blend that was composed of around 48 wt% P(3HB) and 52 wt% mcl-PHA, with an average molecular weight of 4.3 x 10 5 Da and a polydispersity index of 2.2. Two melting temperatures (Tm) were observed for the blend, 52 and 174 ºC, which correspond to the Tm of the mcl-PHA and P(3HB), respectively. P(3HB)/mcl-PHA blend films prepared by the solvent evaporation method had permeabilities to oxygen and carbon dioxide of 2.6 and 32 Barrer, respectively. The films were flexible and easily deformed, as demonstrated by their tensile strength at break of 1.47 +- 0.07 MPa, with a deformation of 338 +- 19% until breaking, associated with a Young modulus of 5.42 +- 1.02 MPa. This study demonstrates for the first time the feasibility of using the co-culture of C. necator and P. citronellolis strains to obtain a natural blend of P(3HB)/mcl-PHA that can be processed into films suitable for applications ranging from commodity packaging products to high-value biomaterials
- Production of medium-chain-length polyhydroxyalkanoates by Pseudomonas chlororaphis subsp. aurantiaca: Cultivation on fruit pulp waste and polymer characterizationPublication . Pereira, João R.; Araújo, Diana; Freitas, Patrícia; Marques, Ana C.; Delgado Alves, Vitor; Sevrin, Chantal; Grandfils, Christian; Fortunato, Elvira; Reis, Maria A.M.; Freitas, FilomenaPseudomonas chlororaphis subsp. aurantiaca DSM 19603 was cultivated on apple pulp, a glucose- and fructoserich waste generated during juice production, to produce medium-chain length polyhydroxyalkanoates. A cell dry mass of 8.74 ± 0.20 g/L, with a polymer content of 49.25 ± 4.08% were attained. The produced biopolymer was composed of 42.7±0.1mol% 3-hydroxydecanoate, 17.9±1.0mol% 3-hydroxyoctanoate, 14.5±1.1mol% 3- hydroxybutyrate, 11.1±0.6 mol% 3-hydroxytetradecanoate, 10.1±0.5 mol% 3-hydroxydodecanoate and 3.7± 0.2 mol% 3-hydroxyhexanoate. It presented low glass transition and melting temperatures (−40.9 ± 0.7 °C and 42.0±0.1 °C, respectively), and a degradation temperature of 300.0±0.1 °C, coupled to a lowcrystallinity index (12.7±2.7%), amolecularweight (Mw) of 1.34 × 105±0.18×105 Da and a polydispersity index of 2.70±0.03. The biopolymer's filmswere dense and had a smooth surface, as demonstrated by Scanning ElectronMicroscopy. They presented a tension at break of 5.21 ± 1.09 MPa, together with an elongation of 400.5 ± 55.8% and an associated Young modulus of 4.86 ± 1.49 MPa, under tensile tests. These attractive filming properties of this biopolymer could potentially be valorised in several areas such as the fine chemicals industry, biomedicine, pharmaceuticals, or food packaging