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

This article presents the results of production and characterization of medium-chain-length polyhydroxyalkanoates (mcl-PHAs) using Pseudomonas sp. Gl01. Studies have been carried out to find suitable feeding strategies for mcl-PHAs production and, for the first time, to investigate in-depth the properties of biopolyesters obtained under controlled conditions with waste rapeseed oil as a substrate. Up to 44% mcl-PHAs of cell dry weight was produced at 41 h of biofermentor culture by employing pulsed feeding of waste rapeseed oil. GC analysis showed a polymer composition with monomer length of C6 to C12 with C8 and C10 as the principal monomers. The monomeric structure of the extracted polyesters did not depend on the cultivation time and the feeding strategy. Molecular weight of the mcl-PHAs was found to be ranging from 57 to 154 kDa. Thermal analyses showed the obtained mcl-polyhydroxyalkanaotes to be semi-crystalline biopolymer with promising thermal stability, having a glass transition temperature of -38 to -50°C.