Abstract
The bacterial strain isolated from soil was identified as Cupriavidus necator IBP/SFU-1 and investigated as a PHA producer. The strain was found to be able to grow and synthesize PHAs under autotrophic conditions and showed a broad organotrophic potential towards different carbon sources: sugars, glycerol, fatty acids, and plant oils. The highest cell concentrations (7–8 g/L) and PHA contents were produced from oleic acid (78%), fructose, glucose, and palm oil (over 80%). The type of the carbon source influenced the PHA chemical composition and properties: when grown on oleic acid, the strain synthesized the P(3HB-co-3HV) copolymer; on plant oils, the P(3HB-co-3HV-co-3HHx) terpolymer, and on the other substrates, the P(3HB) homopolymer. The type of the carbon source influenced molecular-weight properties of PHAs: P(3HB) synthesized under autotrophic growth conditions, from CO2, had the highest number-average (290 ± 15 kDa) and weight-average (850 ± 25 kDa) molecular weights and the lowest polydispersity (2.9 ± 0.2); polymers synthesized from organic carbon sources showed increased polydispersity and reduced molecular weight. The carbon source was not found to affect the degree of crystallinity and thermal properties of the PHAs. The type of the carbon source determined not only PHA composition and molecular weight but also surface microstructure and porosity of the polymer films. The new strain can be recommended as a promising P(3HB) producer from palm oil, oleic acid, and sugars (fructose and glucose) and as a producer of P(3HB-co-3HV) from oleic acid and P(3HB-co-3HV-co-3HHx) from palm oil.
Highlights
The present study investigated the properties of PHAs synthesized by the new strain, Cupriavidus necator IBP/SFU-1, from various carbon sources
Cupriavidus necator IBP/SFU-1 is an obligate aerobic organism and a facultative chemolitho-organotroph; the strain is capable of growing on CO2 and H2 as sole carbon and energy sources, respectively
Results of C. necator IBP/SFU-1 cultivation on sunflower seed oil were lower compared to palm oil and were similar to the results obtained for C. necator B-10646: a cell concentration of 4.3 g/L, a productivity of only 1.77 g/L d, and a polymer content of
Summary
Polymers of hydroxy-derived alkanoic acids, polyhydroxyalkanoates (PHAs), comprise polymers with various chemical compositions, which have valuable properties including biocompatibility and biodegradability. These biopolymers are promising materials of the 21st century for diverse applications from municipal engineering and agriculture to pharmacology and biomedicine [7,8,9,10,11,12]. Conditions under which the direction of cell anabolism changes from protein synthesis to PHA synthesis and accumulation are determined by the redox state of cytoplasm and intracellular concentrations of pyruvate and available
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