Waste rapeseed oil as a substrate for medium‐chain‐length polyhydroxyalkanoates production

Abstract

Medium-chain-length polyhydroxyalkanoates (mcl-PHAs) are biodegradable, biocompatible polyesters produced by many bacteria as intracellular storage compounds of energy and carbon. They have gained great attention as a new green alternative to petrochemical plastic such as polypropylene. The present study was focused on mcl-PHA production by two Pseudomonas strains (Gl01 and Gl06). To make this process more economical, waste rapeseed oil was used as a carbon source. The levels of PHAs synthesized by Pseudomonas sp. Gl01 strain and Gl06 strain were 21.0%, and 19.3% of CDW, respectively. The polyester accumulation increased until nitrogen and oxygen were depleted from the medium. Reverse transcription real-time PCR approach was applied to quantitatively evaluate phaC1, phaC2, and phaZ gene expression. A positive correlation was found between the cellular PHA content and the gene expression of the PHA synthases. The transcriptional analysis revealed that the phaC1 and phaZ genes could be co-transcribed. The overexpressed phaC2 gene was only observed in the Gl06 strain. The monomeric composition of the obtained mcl-PHA was dependent on the strain: 3-hydroxyoctanoic acid (3HO) and 3-hydroxydecanoic acid (3HD) were dominant in strain Gl01, whereas 3-hydroxyhexanoic (3HHx) was present in significant amounts in strain Gl06.Practical applications: This article presents the procedure of medium-chain-length polyhydroxyalkanoates (mcl-PHAs) synthesis by the Pseudomonas Gl01 and Gl06 strains from waste rapeseed oil as a feedstock. Beside the microbial production of these environmentally friendly plastics, this approach also represents a new way of utilizing waste oils. The knowledge of the key enzymes involved in mcl-PHAs accumulation is necessary in order to understand the mechanisms of their synthesis, and to use them effectively in biotechnological applications.

Pulsed feeding strategy is more favorable to medium‐chain‐length polyhydroxyalkanoates production from waste rapeseed oil

“…Our previous results demonstrated that the level of mcl‐PHAs stored by Pseudomonas sp. Gl01 growing on medium supplemented with a lower concentration of waste rapeseed oil was 21.0% of CDW . This seems to suggest that a higher concentration of this carbon source increases mcl‐PHAs synthesis in bacterial cells.…”

“…Mcl‐PHAs were extracted from liophilized cells using the chloroform/methanol procedure for quantitative and qualitative analysis of biopolymers. The monomeric composition of the purified mcl‐PHAs was determined using a methanolysis protocol as described previously . The concentrations of methyl esters were estimated by a gas chromatography (GC) equipped with a capilary column Varian VF‐5 ms with a film thickness of 0.25 μm (Varian, Lake Forest, USA).…”

“…Our previous studies have demonstrated that Pseudomonas sp. Gl01 is able to produce large amounts of mcl‐PHAs from renewable resources such as waste plant oils . However, the aim of these cultures was to evaluate the effect of two step fed‐batch fermentation with combination of glucose and waste rapeseed oil, and pulsed feeding fed‐batch cultivation (by addition of 14 mL/L waste oil) on the productivity of mcl‐PHAs.…”

“…Gl01 is able to produce large amounts of mcl‐PHAs from renewable resources such as waste plant oils . However, the aim of these cultures was to evaluate the effect of two step fed‐batch fermentation with combination of glucose and waste rapeseed oil, and pulsed feeding fed‐batch cultivation (by addition of 14 mL/L waste oil) on the productivity of mcl‐PHAs. In the current report, for the first time, the pulsed and continuous feeding strategies in the fed‐batch bioreactors supplemented with waste rapeseed oil were compared with respect to the mcl‐PHAs productivity and the growth of Pseudomonas sp.…”

Utilization of Waste Carbon Source as Substrate and Economical Production of Biopolymer Polyhydroxyalkanoate Through Bacterial Consortia

“…Możejko and Ciesielski (2013) reported that the newly isolated Gl01 strain belonging to the Pseudomonas species was capable of producing up to 48% mcl-PHA at 17 hrs from the culture using saponified palm oil as source of carbon. A high concentration of PHAs was reached by Możejko et al (2011Możejko et al ( , 2012) during culture of Cupriavidus necator using waste rapeseed oil which was supplied as a sole substrate in the bioreactor.…”