Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) production by mutant PRP 25 of Pandoraea SP. from glycerol and propionic acid via high-cell-density fed-batch fermentation

Abstract

Polyhydroxyalkanoates (PHAs) are microbial polyesters which are composed of 3-hydroxy fatty acid monomers. Among approximately 150 different constituents of PHAs, the poly(3-hydroxybutyrate) (P3HB) is the most common type and extensively studied. The P3HB resemble the physical and chemical properties of petroleum-based polypropylene (PP) and so can replace some nonbiodebradable plastics. However, the P3HB application range has been limited due to its high crystallinity and low extension to break. These unfavorable characteristics can be improve by co-monomers incorporation such as 3-hydroxyvalerate (3HV) to produce the copolymer P3HB-co-3HV resulting in appropriate characteristics for thermoplastic processing. Since the PHAs production has been limited by its relative expensive cost, alternative solutions have been proposed to minimize the costs with carbon sources implementing waste materials or industrial byproducts. Thus, the glycerol, the main byproduct of biodiesel industry, is becoming a good candidate to solve this problem since it has a low value. Therefore, the aim of this research internship project is to continue the cultivation experiments on larger scale with the mutant prp 25 of Pandoraea sp. obtained in previous experiments (Processo FAPESP: 2012/18646-1). The P3HB-co-3HV production from glycerol and propionic acid by the selected strain will be performed at 42 l scale-bioreactor via high-cell-density fed-batch fermentation, which will be analyze the effect of feeding regimen with glycerol 50% and 80% (v/v); and the culture supplementation of NaCl, MgSO4.7H2O and KH2PO4 salts on the polymer production. (AU)