Recent Updates on the Biodegradation of Polyhydroxyalkanoates

There have been many studies carried out with the aim of increasing the degradation of PHA. The rate of degradation is crucial especially when the PHA film is applied in the medical field. 

Faezah and co-workers [22] reported an enzymatic degradation study comparing solvent-cast film and salt-leached film. The PhaZ enzyme in this study was obtained from Acidovorax sp. It was reported that the enzymatic degradability of the salt-leached film was higher than 

Wang and co-workers [24] reported isolating the enzyme which degrades poly(3HB-co-3HV). The degradation of poly(3HB-co-3HV) was found to depend on the extracellular enzymes present in the supernatant. The effect of pH on enzyme activity was evaluated and it was found that the degrading activity of the enzyme increased upon increasing the pH. However, when the temperature was raised, the enzyme activity decreased as did the degradation of poly(3HB-CO-3HV). 

Recently, the production of a biodegradable plastic-degrading enzyme from cheese whey by the phyllosphere yeast Pseudozyma antartica GB-4(1)W was studied [25]. It was reported that this yeast produces a cutinase-like enzyme, PaE, which has the ability to degrade biodegradable plastics. This enzyme was reported to have the ability to degrade several bioplastics such as PBS, polybutylene succinate-co-adipate, poly(e-caprolactone) and polylactic acid. Fed-batch cultivation of this yeast in xylose resulted in the production of PaE with high productivity. 

Mukai and K. Yamada in Biodegradable Plastics and Polymers, Elsevier, Amsterdam, The Netherlands, 1994, p.39. 

---