RESUMO
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.
Assuntos
Plasmídeos/genética , Poli-Hidroxialcanoatos/biossíntese , Poli-Hidroxialcanoatos/genética , Pseudomonas/genética , Pseudomonas/metabolismo , Ácido 3-Hidroxibutírico/metabolismo , Aciltransferases/genética , Aeromonas/genética , Aeromonas hydrophila/genética , Antibacterianos , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Caproatos/metabolismo , Cromossomos Bacterianos , Meios de Cultura/química , Cupriavidus necator/genética , Ácidos Decanoicos/metabolismo , Glucose/metabolismo , Mutação , Pseudomonas/enzimologia , Transformação BacterianaRESUMO
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%.
RESUMO
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.