Oxidized Polyethylene Wax as a Potential Carbon Source for PHA Production

Abstract

We report on the ability of bacteria to produce biodegradable polyhydroxyalkanoates (PHA) using oxidized polyethylene wax (O-PEW) as a novel carbon source. The O-PEW was obtained in a process that used air or oxygen as an oxidizing agent. R. eutropha H16 was grown for 48 h in either tryptone soya broth (TSB) or basal salts medium (BSM) supplemented with O-PEW and monitored by viable counting. Study revealed that biomass and PHA production was higher in TSB supplemented with O-PEW compared with TSB only. The biopolymers obtained were preliminary characterized by nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The detailed structural evaluation at the molecular level was performed by electrospray ionization tandem mass spectrometry (ESI-MS/MS). The study revealed that, when TSB was supplemented with O-PEW, bacteria produced PHA which contained 3-hydroxybutyrate and up to 3 mol % of 3-hydroxyvalerate and 3-hydroxyhexanoate co-monomeric units. The ESI-MS/MS enabled the PHA characterization when the content of 3-hydroxybutyrate was high and the appearance of other PHA repeating units was very low.

Microbial Degradation and Valorization of Plastic Wastes

“…Another bacterial strain, Ralstonia eutropha H16 (previously known as Cuprivadus necator or Wausternia eutropha), also exhibited PHA accumulation when supplied with non-oxygenated PE pyrolytic hydrocarbons as a carbon source in a nitrogen-rich tryptone soya broth (TSB) growth medium (Johnston et al, 2017). In contrast to PE pyrolysis in the absence of air, pyrolysis in the presence of air would not only cleave the long chains of PE but also introduce the carbonyl and hydroxyl groups into the backbone of pyrolytic hydrocarbons, which could improve the bioavailability of pyrolytic hydrocarbons as a carbon source for microbial fermentation to produce PHA by the strain Ralstonia eutropha H16 (Radecka et al, 2016). In addition, PP could also be depolymerized into branched chain fatty alcohols and alkenes by pyrolysis.…”

Recent Advances in Sustainable Plastic Upcycling and Biopolymers

“…[ 140 ] R. eutropha H16 has also been reported to produce PHAs from both of oxidized PE wax, obtained from oxidation process, and non‐oxygenated PE wax, obtained from pyrolysis process: the produced PHA from oxidized PE wax consists of 3HB, 3HV and 3HHx monomer units and the other PHA, produced from non‐oxygenated PE wax, consists of 3HB and 3HV monomer units. [ 141,142 ] In addition, PP waste fragments were converted into P(3HB‐ ter ‐3HV‐ ter ‐3HHx) by using R. eutropha H16 as the host strain. [ 143 ] There also has been reports using TPA as the carbon source formed from PET pyrolysis for further production of PHAs.…”

Forensic engineering of advanced polymeric materials Part IV: Case study of oxo-biodegradable polyethylene commercial bag – Aging in biotic and abiotic environment

“…Hoverer, PE wastes could be valuable materials for production compostable polymers as e.g. reported recently by some of us on the ability of bacteria to produce biodegradable polyhydroxyalkanoates (PHA) using oxidized polyethylene wax as a novel carbon source (Radecka et al 2016).…”