PHA from Acetic Acid: Manipulating Microbial Production of Polyhydroxyalkanoates for use in Steel Coatings.

This research sought to determine the impact of various culture parameters on the composition of polyhydroxyalkanoate (PHA), which was intended for use in steel coating. PHAs are biodegradable biopolymers that can be made by glycogen accumulating organisms (GAOs), which produce two types of monomers, 3-hydroxybutyrate (HB), and 3-hydroxyvalerate (HV). Several different culture parameters (acetate concentration, nitrogen and phosphate availability, temperature and pH) were varied and their effect on the PHA composition was measured. The results showed that the HB relative content was lower at acetate concentrations higher than 6 g/L and pH 6.5 and 7. The HV content increased from 26% to 43% for 18°C and 28°C, respectively. Nitrogen concentration did not influence PHA composition whereas 100 mg/L of phosphate induced a HV content equal to 47%. A positive Pearson correlation between HB content and PHA yield was found in this research. This study showed how the culture conditions might be varied to change the PHA composition to serve a specific function, like replacing steel coating with biodegradable polymers.