New tailor-made PHB-based nanocomposites for high performance applications produced from environmentally friendly production routes

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Efficient P(3HB) extraction from Burkholderia sacchari cells using non-chlorinated solvents

Publication . Rosengart, Alessandro; Cesário, M.Teresa; Almeida, M. Catarina M.D. de; Raposo, Rodrigo S.; Espert, Ana; Díaz de Apodaca, Elena; Fonseca, M. Manuela R. da

"A technique using safer, non-chlorinated organic solvents for the extraction of poly-3-hydroxybutyrate (P(3HB)) from bacterial cells was developed, aiming to attain high recovery yields and purities. Some solvents were selected from the GlaxoSmithKline guide as sustainable industrial solvents and the solubility of P(3HB) calculated using predictive equations from literature. Based on the calculated solubility values, anisole, cyclohexanone and phenetole were tested as extraction solvents and the relevant process variables (extraction temperature, extraction time and mass of cells/solvent volume ratio) were addressed. Polymer recovery yields of 97% and 93% were obtained with anisole and cyclohexanone, respectively, at 120–130 °C using a cell/solvent ratio of 1.5% (w/v). Maximum polymer purities using these experimental conditions were 98% for both solvents. The recovery yield and the polymer purity attained with chloroform (reference solvent) were 96 and 98%, respectively. Higher cell/solvent ratios of 6.0% (w/v) showed slightly lower recovery yields and purities. The average molecular weight and the thermal properties of the polymers extracted with the alternative solvents were fully comparable to those of the polymers obtained by chloroform extraction, demonstrating that the applied conditions did not significantly alter the properties of the extracted P(3HB)."

2015-11Journal article

Open access

Biodegradable polyesters from agro&industrial by-products

Publication . Almeida, Catarina Dias de; Cavalheiro, João; Raposo, Rodrigo; Cesário, Teresa; Ferreira, Frederico; Ferreira, Bruno; van Keulen, Frederik; Pollet, Eric; Fonseca, M. Manuela R. da

2014-05Conference object

Open access

Enhanced bioproduction of poly-3-hydroxybutyrate from wheat straw lignocellulosic hydrolysates

Publication . Cesário, M. Teresa; Raposo, Rodrigo S.; Almeida, M. Catarina M. D. de; Keulen, Frederik van; Ferreira, Bruno S.; Fonseca, M. Manuela R. da

"Polyhydroxyalkanoates (PHAs) are bioplastics that can replace conventional petroleum derived products in various applications. One of the major barriers for their widespread introduction in the market is the higher production costs when compared with their petrochemical counterparts. In this work, a process was successfully implemented with high productivity based on wheat straw, a cheap and readily available agricultural residue, as raw material. The strain Burkholderia sacchari DSM 17165 which is able to metabolize glucose, xylose and arabinose, the main sugars present in wheat straw hydrolysates (WSH), was used. Results in shake flask showed that B. sacchari cells accumulated ca 70 % g P(3HB)/g cell-dry-weight with a yield of polymer on sugars (YP/S) of 0.18 g/g when grown on a mixture of commercial C6 and C5 sugars (control), while these values reached ca 60 % g P(3HB)/g cell-dry-weight and 0.19 g/g, respectively, when WSHs were used as carbon source. In fed-batch cultures carried out in 2L stirred tank reactors on WSH, a maximum polymer concentration of 105 g/L was reached after 61 h of cultivation corresponding to an accumulation of 72% of CDW. Polymer yield and productivity were 0.22 g P(3HB)/g total sugar consumed and 1.6 g/L. h, respectively. The selected feeding strategy successfully overcame the carbon catabolite repression phenomenon observed in sugar mixtures containing hexoses and pentoses. This is the first work describing fed-batch cultivations aiming at PHA production using real lignocellulosic hydrolysates. Additionally, the P(3HB) volumetric productivities attained are, by far, the highest achieved ever on agricultural wastes hydrolysates."

2014-01Journal article

Open access

Production of poly (3-hydroxybutyrate-co-4-hydroxybutyrate) by Burkholderia sacchari using wheat straw hydrolysates and gamma-butyrolactone

Publication . Cesário, M. Teresa; Raposo, Rodrigo S.; Almeida, M. Catarina M. D. de; Van Keulen, Frederik; Ferreira, Bruno S.; Telo, João P.; Fonseca, M. Manuela R. da

"Burkholderia sacchari DSM 17165 is able to grow and produce poly(3-hydroxybutyrate) both on hexoses and pentoses. In a previous study, wheat straw lignocellulosic hydrolysates (WSH) containing high C6 and C5 sugar concentrations were shown to be excellent carbon sources for P(3HB) production. Using a similar feeding strategy developed for P(3HB) production based on WSH, fedbatch cultures were developed aiming at the production of the copolymer P(3HB-co- 4HB) (poly(3-hydroxybutyrate-co-4-hydroxybutyrate)) by B. sacchari. The ability of this strain to synthesize P(3HB-co-4HB) was first shown in shake flasks using gammabutyrolactone (GBL) as precursor of the 4HB units. Fed-batch cultures using glucose as carbon source (control) and GBL were developed to achieve high copolymer productivities and 4HB incorporations. The attained P(3HBco- 4HB) productivity and 4HB molar % were 0.7 g/(L·h) and 4.7 molar %, respectively. The 4HB incorporation was improved to 6.3 and 11.8 molar % by addition of 2 g/L propionic and acetic acid, respectively. When WSH were used as carbon source under the same feeding conditions, the values achieved were 0.5 g/(L·h) and 5.0 molar %, respectively. Burkholderia sacchari, a strain able to produce biopolymers based on xylose-rich lignocellulosic hydrolysates, is for the first time reported to produce P(3HB-co-4HB) using gamma butyrolactone as precursor."

2014-11Journal article

Open access

Feeding strategies for tuning poly (3-hydroxybutyrate-co-4-hydroxybutyrate) monomeric composition and productivity using Burkholderia sacchari

Publication . Raposo, Rodrigo S.; Almeida, M. Catarina M. D. de; Fonseca, M. M. R. da; Cesário, M. Teresa

Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-4HB)) co-polymers were produced at bench-scale in fed-batch cultivations by Burkholderia sacchari from glucose (main carbon-source) and gamma-butyrolactone (GBL) as co-substrate. As P(3HB-4HB) properties highly depend on the 4-hydroxybutyrate (4HB) molar fraction, it is advantageous to have a thorough knowledge of the process in order to promote the production of the targeted final product. In this work, polymers with a 4HB molar percentage ranging from 1.5 to 8.4% (mol/mol) were obtained as consequence of a fine tuning of the fed-batch operation conditions, namely regarding the co-substrate feeding rate and its addition time, as GBL is toxic to B. sacchari cells. The best results regarding both the 4HB incorporation (molar%) and the co-polymer productivity (7.1% and 1.1g/(L.h) respectively) were reached when a pulse of GBL (<10g/L) was added early in the accumulation phase followed by a constant GBL addition at a rate similar to that of consumption so that a steady co-substrate concentration in the medium was maintained.

2017-12Journal article

Restricted access