Polyhydroxyalkanoate (PHA) is a family of microbial polyesters that is completely biodegradable and possesses the mechanical and thermal properties of some commonly used petrochemical-based plastics. Therefore, PHA is attractive as a biodegradable thermoplastic. It has always been a challenge to commercialize PHA due to the high cost involved in the biosynthesis of PHA via bacterial fermentation and the subsequent purification of the synthesized PHA from bacterial cells. Innovative enterprise by researchers from various disciplines over several decades successfully reduced the cost of PHA production through the efficient use of cheap and renewable feedstock, precisely controlled fermentation process, and customized bacterial strains. Despite the fact that PHA yields have been improved tremendously, the recovery and purification processes of PHA from bacterial cells remain exhaustive and require large amounts of water and high energy input besides some chemicals. In addition, the residual cell biomass ends up as waste that needs to be treated. We have found that some animals can readily feed on the dried bacterial cells that contain PHA granules. The digestive system of the animals is able to assimilate the bacterial cells but not the PHA granules which are excreted in the form of fecal pellets, thus resulting in partial recovery and purification of PHA. In this mini-review, we will discuss this new concept of biological recovery, the selection of the animal model for biological recovery, and the properties and possible applications of the biologically recovered PHA.
Utilization of neglected oils for polyhydroxyalkanoates (PHAs) production will provide vast arrays of carbon substrates, lower its production cost, and boost global PHA production. The scope of this study is to evaluate the potential of desert date oil, bitter apple oil, African elemi oil, and Amygdalus pedunculata oil from Africa and some parts of Asia as novel carbon sources for PHA production. The desert date kernels and bitter apple seeds contain up to 45.5 and 53.2% of oil‐based on dry weight. Fatty acid methyl ester (FAME) results showed the presence of palmitic (C16:0), stearic (C18:0), oleic (C18:1), and linoleic (C18:2) acids as the major fatty acids constituting 97–99% of the total fatty acids. Both strains of Cupriavidus necator H16 and Re2058/pCB113 utilizes the oils effectively as carbon sources for poly(3‐hydroxybutyrate), P(3HB) and poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate), P(3HB‐co‐3HHx) production, respectively. A maximum cell dry weight (CDW) of 8–9 g/L−1 (C. necator H16) and 6–8 g L−1 (Re2058/pCB113) at a C/N ratio between 24 and 36 was achieved from shake flask cultures. The oils are suitable for the biosynthesis of high concentration of P(3HB) (6 g L−1) and P(3HB‐co‐3HHx) (5 g L−1) with 31 mol% 3HHx. Gel permeation chromatographic (GPC) analysis of the PHAs revealed high PHA molecular weights (Mw) of 510 000–630 000 for copolymer and 1 580 000–2 400 000 Da for homo‐polymer. This study shows that the underutilized oils are potential feedstock to produce PHA that can substitute palm oil.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.