Marine photosynthetic purple bacteria produce high molecular weight bioplastics

August 18, 2016

Progress toward practical use of biodegradable and biocompatible plastics

RIKEN CSRS researchers have discovered that a strain of marine purple photosynthetic bacteria produces high molecular weight polyhyroxyalkanoate (PHA).

Although several cases of PHA production by photosynthetic bacteria have been reported, almost all were freshwater organisms. RIKEN CSRS researchers came up with the idea of using seawater as a growth medium–specifically, a high-salt medium that would reduce the presence of other bacteria–with the eventual aim of realizing practical industrial applications.

When researchers looked at 12 strains of marine purple sulfur and purple non-sulfur photosynthetic bacteria, they found all 12 strains produced PHA. Their results also demonstrated that PHA production was possible with artificial seawater. Examination of the PHA properties revealed that some of the sulfur and non-sulfur strains synthesized very high molecular weight PHAs.

Given that other research has reported a reduction in PHA molecular weight upon extraction and purification, the high molecular weight PHA obtained in this research can be deemed as a useful research material. Higher molecular weight PHA has improved physical properties such as tensile strength and stretchability. In the future, optimizing PHA production with carbon dioxide should contribute to reducing the environmental impact of plastic production.


Original article
PLoS ONE doi: 10.1371/journal.pone.0160981
Higuchi-Takeuchi, M. Morisaki, K. Toyooka, K. and Numata, K.,
"Synthesis of high-molecular-weight polyhydroxyalkanoates by marine photosynthetic purple bacteria".

Keiji Numata; Team Leader
Mieko Higuchi; Research Scientist
Enzyme Research Team