Abstract

Diverse microorganisms are studied in order to improve the production of biotechnological compounds. Bacteria are widely studied for the synthesis of bioactive metabolites and biopolymers. Burkholderia xenovorans LB400 is an aerobic and non-pathogenic strain that has been used as a model bacterium to study the degradation of a wide range of aromatic compounds. B. xenovorans LB400 possesses the genes biosynthesis of polyhydroxyalkanoates (PHAs). The objective of this study was to evaluate the P(3HB) synthesis by strain LB400. Strain LB4000 is able to synthesize both the poly(3-hydroxybutyrate) homopolymer [P(3HB)] and the poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolymer [P(3HB-co-3HV)]. The nature of the carbon source not only determines the PHA content, but also the composition of monomers, which define the properties of the polymer. Strain LB400 produces P(3HB) during culture using sugars such as mannitol, glucose, gluconate and fructose as carbon sources. The polymer P(3HB) produced by strain LB400 was characterized by gas chromatography with flame ionization detector (GC-FID), infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (1H and 13C NMR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). P(3HB) granule in cells was observed by electron microscopy. P(3HB) was quantified using GC-FID. The kinetic parameters and conditions of batch culture were determined for P(3HB) produced by strain LB400. B. xenovorans LB400 showed a tendency to accumulate elevated amounts of the 3HB monomer (100 mol%) with a high accumulation of P(3HB) (45%). This study showed that B. xenovorans LB400 is an attractive bacterium for producing P(3HB) during culture with sugars as source carbon and nitrogen as a limiting nutrient. The optimization of PHAs production by B. xenovorans LB400 will be discussed.