Carriers based on poly-3-hydroxyalkanoates containing nanomagnetite to trigger hormone release.

Poly-3-hydroxybutyrate (P(3HB)) and poly-3-hydroxybutyrate-co-3-hydroxyhexanoate (P(3HB-co-3HHx)) are biocompatible and bioabsorbable biopolymers produced by different bacteria with potential for drug delivery in thermo-responsive magnetic microcarriers. Microparticles of P(3HB) and P(3HB-co-3HHx), with 5.85% mol of 3HHx, produced by Burkholderia sacchari, containing nanomagnetite (nM) and lipophilic hormone were prepared by simple emulsion (oil/water) technique leading to progesterone (Pg) encapsulation efficiency higher than 70% and magnetite loads of 3.1 and 2.3% (w/w) for P(3HB)/nM/Pg and P(3HB-co-3HHx)/nM/Pg, respectively. These formulations were characterized by Infrared spectroscopy, X-ray diffraction, Thermal gravimetric analysis and Electron microscopy (TEM, SEM) techniques. The P(3HB)/nM/Pg and P(3HB-co-3HHx)/nM/Pg microparticles presented spherical geometry with wrinkled surfaces and average size between 2 and 40 µm for 90% of the microparticles. The release profiles of the P(3HB)/nM/Pg and P(3HB-co-3HHx)/nM/Pg formulations showed a hormone release trigger (6.9 and 11.1%, respectively) effect induced by oscillating external magnetic field (0.2 T), after 72 h. Progesterone release in non-magnetic tests with P(3HB-co-3HHx)/nM/Pg revealed a slight increment (5.6%) in relation to P(3HB)/nM/Pg. The experimental release of the P(3HB)/nM/Pg and P(3HB-co-3HHx)/nM/Pg samples presented a good agreement with Higuchi model. The 3HHx comonomer content improves the hormone release of the P(3HB-co-3HHx)/nM/Pg formulation with potential for application to synchronize the estrous cycle.

Production of Polyhydroxyalkanoates Copolymers by Recombinant Pseudomonas in Plasmid- and Antibiotic-Free Cultures.

Three different polyhydroxyalkanoate (PHA) synthase genes (Ralstonia eutropha H16, Aeromonas sp. TSM81 or Aeromonas hydrophila ATCC7966 phaC) were introduced into the chromosome of two Pseudomonas strains: a native medium-chain-length 3-polyhydroxyalkanoate (PHAMCL) producer (Pseudomonas sp. LFM046) and a UV-induced mutant strain unable to produce PHA (Pseudomonas sp. LFM461). We reported for the first time the insertion of a chromosomal copy of phaC using the transposon system mini-Tn7. Stable antibiotic marker-free and plasmid-free recombinants were obtained. Subsequently, P(3HB-co-3HAMCL) was produced by these recombinants using glucose as the sole carbon source, without the need for co-substrates and under antibiotic-free conditions. A recombinant harboring A. hydrophila phaC produced a terpolyester composed of 84.2 mol% of 3-hydroxybutyrate, 6.3 mol% of 3-hydroxyhexanoate, and 9.5 mol% of 3-hydroxydecanoate from only glucose. Hence, we were successful in increasing the industrial potential of Pseudomonas sp. LFM461 strain by producing PHA copolymers containing 3HB and 3HAMCL using an unrelated carbon source, for the first time in a plasmid- and antibiotic-free bioprocess.

Draft Genome Sequence of the Polyhydroxyalkanoate-Producing Bacterium Burkholderia sacchari LMG 19450 Isolated from Brazilian Sugarcane Plantation Soil.

Burkholderia sacchari LMG 19450, isolated from the soil of a sugarcane plantation in Brazil, accumulates large amounts of polyhydroxyalkanoates from sucrose, xylose, other carbohydrates, and organic acids. We present the draft genome sequence of this industrially relevant bacterium, which is 7.2 Mb in size and has a G+C content of 64%.

Polyhydroxyalkanoate biosynthesis and simultaneous remotion of organic inhibitors from sugarcane bagasse hydrolysate by Burkholderia sp.

Burkholderia sp. F24, originally isolated from soil, was capable of growth on xylose and removed organic inhibitors present in a hemicellulosic hydrolysate and simultaneously produced poly-3-hydroxybutyrate (P3HB). Using non-detoxified hydrolysate, Burkholderia sp. F24 reached a cell dry weight (CDW) of 6.8 g L(-1), containing 48 % of P3HB and exhibited a volumetric productivity (PP3HB) of 0.10 g L(-1) h(-1). Poly-3-hydroxybutyrate-co-3-hydroxyvalerate copolymers (P3HB-co-3HV) were produced using xylose and levulinic acid (LA) as carbon sources. In shake flask cultures, the 3HV content in the copolymer increased from 9 to 43 mol% by adding LA from 1.0 to 5.0 g L(-1). In high cell density cultivation using concentrated hemicellulosic hydrolysate F24 reached 25.04 g L(-1) of CDW containing 49 % of P3HB and PP3HB of 0.28 g L(-1 )h(-1). Based on these findings, second-generation ethanol and bioplastics from sugarcane bagasse is proposed.

Perspectives on the production of polyhydroxyalkanoates in biorefineries associated with the production of sugar and ethanol.

Polyhydroxyalkanoates (PHA) are biodegradable and biocompatible bacterial thermoplastic polymers that can be obtained from renewable resources. The high impact of the carbon source in the final cost of this polymer has been one of the major limiting factors for PHA production and agricultural residues, mainly lignocellulosic materials, have gained attention to overcome this problem. In Brazil, production of 2nd generation ethanol from the glucose fraction, derived from sugarcane bagasse hydrolysate has been studied. The huge amounts of remaining xylose will create an opportunity for the development of other bioprocesses, generating new products to be introduced into a biorefinery model. Although PHA production from sucrose integrated to a 1G ethanol and sugar mill has been proposed in the past, the integration of the process of 2G ethanol in the context of a biorefinery will provide enormous amounts of xylose, which could be applied to produce PHA, establishing a second-generation of PHA production process. Those aspects and perspectives are presented in this article.