Characterization of medium chain length polyhydroxyalkanoate produced from olive oil deodorizer distillate.

Olive oil deodorizer distillate (OODD) was used for the first time as the sole substrate for polyhydroxyalkanoates (PHA) production by the bacterium Pseudomonas resinovorans in bioreactor cultivation. A PHA content in the biomass of 36 ± 0.8 wt% was attained within 19 h of cultivation. A final polymer concentration of 4.7 ± 0.3 gL(-1) was reached, corresponding to a volumetric productivity of 5.9 ± 0.2 gL(-1)day(-1). The PHA was composed of 3-hydroxyoctanoate (48.3 ± 7.3 mol%), 3-hydroxydecanoate (31.6 ± 2.6 mol%), 3-hydroxyhexanoate (12.1 ± 1.1 mol%) and 3-hydroxydodecanoate (8.0 ± 0.7 mol%) and it had a glue-like consistency that did not solidify at room temperature. The polymer was highly amorphous, as shown by its low crystallinity of 6 ± 0.2%, with low melting and glass transition temperatures of 36 ± 1.2 and -16 ± 0.8°C, respectively. The polymer exhibited a shear thinning behavior and a mechanical spectrum with a predominant viscous contribution. Its shear bond strength for wood (67 ± 9.4 kPa) and glass (65 ± 7.3 kPa) suggests it may be used for the development of biobased glues.

Valorization of fatty acids-containing wastes and byproducts into short- and medium-chain length polyhydroxyalkanoates.

Olive oil distillate (OOD), biodiesel fatty acids-byproduct (FAB) and used cooking oil (UCO) were tested as inexpensive carbon sources for the production of polyhydroxyalkanoates (PHA) with different composition using twelve bacterial strains. OOD and FAB were exploited for the first time as alternative substrates for PHA production. UCO, OOD and FAB were used by Cupriavidus necator and Pseudomonas oleovorans to synthesize the homopolymer poly-3-hydroxybutyrate, while Pseudomonas resinovorans and Pseudomonas citronellolis produced mcl-PHA polymers mainly composed of hydroxyoctanoate and hydroxydecanoate monomers. The highest polymer content in the biomass was obtained for C. necator (62 wt.%) cultivated on OOD. Relatively high mcl-PHA content (28-31 wt.%) was reached by P. resinovorans cultivated in OOD. This study shows, for the first time, that OOD is a promising substrate for PHA production since it gives high polymer yields and allows for the synthesis of different polymers (scl- or mcl-PHA) by selection of the adequate strains.

Online monitoring of P(3HB) produced from used cooking oil with near-infrared spectroscopy.

Online monitoring process for the production of polyhydroxyalkanoates (PHA), using cooking oil (UCO) as the sole carbon source and Cupriavidus necator, was developed. A batch reactor was operated and hydroxybutyrate homopolymer was obtained. The biomass reached a maximum concentration of 11.6±1.7gL(-1) with a polymer content of 63±10.7% (w/w). The yield of product on substrate was 0.77±0.04gg(-1). Near-infrared (NIR) spectroscopy was used for online monitoring of the fermentation, using a transflectance probe. Partial least squares regression was applied to relate NIR spectra with biomass, UCO and PHA concentrations in the broth. The NIR predictions were compared with values obtained by offline reference methods. Prediction errors to these parameters were 1.18, 2.37 and 1.58gL(-1) for biomass, UCO and PHA, respectively, which indicate the suitability of the NIR spectroscopy method for online monitoring and as a method to assist bioreactor control.

Conversion of fat-containing waste from the margarine manufacturing process into bacterial polyhydroxyalkanoates.

A fat-containing waste produced from the margarine manufacturing process was tested as a low cost carbon source for cultivation of different polyhydroxyalkanoates (PHAs) producing bacterial strains, including Cupriavidus necator, Comamonas testosteroni and several Pseudomonas strains. The margarine waste was mainly composed of free fatty acids (76wt.%), namely mystiric, oleic, linoleic and stearic acids. In preliminary shake flask experiments, several strains were able to grow on the margarine waste, but C. necator reached the highest PHA content in the biomass (69wt.%). This strain was selected for batch bioreactor experiments, wherein it reached a cell dry weight of 11.2g/L with a polymer content of 56wt.%. The culture produced 6.4g/L of polyhydroxybutyrate, P3(HB), within 20h of cultivation, which corresponds to a volumetric productivity of 0.33gPHA/Lh. The P3(HB) polymer produced by C. necator from the margarine waste had a melting point of 173.4°C, a glass transition temperature of 7.9°C and a crystallinity of 56.6%. Although the bioprocess needs to be optimized, the margarine waste was shown to be a promising substrate for P(3HB) production by C. necator, resulting in a polymer with physical and chemical properties similar to bacterial P(3HB) synthesized from other feedstocks.

Recovery of amorphous polyhydroxybutyrate granules from Cupriavidus necator cells grown on used cooking oil.

Used cooking oil (UCO) was employed as the sole carbon source for the production of polyhydroxybutyrate (PHB) by cultivation in batch mode of Cupriavidus necator DSM 428. The produced biomass was used for extraction of the PHB granules with a solvent-free approach using sodium dodecyl sulfate (SDS), ethylenediaminetetraacetic acid (EDTA), and the enzyme Alcalase in an aqueous medium. The recovered PHB granules showed a degree of purity higher than 90% and no crystallization (i.e., granules were recovered in their 'native' amorphous state) as demonstrated by wide angle X-ray diffraction (WAXS). Granules were characterized according to their thermal properties and stability by differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Results show that UCO can be used as a renewable resource to produce amorphous PHB granules with excellent properties in a biocompatible manner.

Production of polyhydroxyalkanoates from spent coffee grounds oil obtained by supercritical fluid extraction technology.

Spent coffee grounds (SCG) oil was obtained by supercritical carbon dioxide (scCO2) extraction in a pilot plant apparatus, with an oil extraction yield of 90% at a 35kgkg(-1) CO2/SCG ratio. Cupriavidus necator DSM 428 was cultivated in 2L bioreactor using extracted SCG oil as sole carbon source for production of polyhydroxyalkanoates. The culture reached a cell dry weight of 16.7gL(-1) with a polymer content of 78.4% (w/w). The volumetric polymer productivity and oil yield were 4.7gL(-1)day(-1) and 0.77gg(-1), respectively. The polymer produced was a homopolymer of 3-hydroxybutyrate with an average molecular weight of 2.34×10(5) and a polydispersity index of 1.2. The polymer exhibited brittle behaviour, with very low elongation at break (1.3%), tensile strength at break of 16MPa and Young's Modulus of 1.0GPa. Results show that SCG can be a bioresource for polyhydroxyalkanoates production with interesting properties.