Bark biorefinery project and PHAs

Chief Innovation and Science Officer Dr Elspeth MacRae and Science Leader Biopolymers & Chemicals Dr Florian Graichen explain their work at Scion on a “fascinating” group of polymers called polyhydroxyalkanoates (PHAs).

Transcript

Dr Elspeth MacRae

One of the technologies that Scion’s working with is how can we take all of the waste on the plantation floor – the slash. We can make a mobile unit, and we can actually turn that into precursor materials and precursor chemicals. We can also take the fibre and the biomass from it and use that to then make sugars and that the microbes can use to make plastics and go through the circle again. So it’s a way of clearing away the waste and giving a reason for people to capture that waste rather than leave it in the forest.

Dr Florian Graichen

We are now just in the first year of a multi-year, multi-million dollar project called bark biorefinery to have the underutilised source bark in New Zealand where we have millions of tonnes either lying on the ground or left in the forest and to use material out of bark in polymer applications. One example of the bioplastics we’re working on here are polyhydroxyalkanoates (PHA), and this is a very, very fascinating group of polymers produced by microbes.

Dr Elspeth MacRae

We store glycogen as energy, plants store starch as energy and these microbes store these bioplastic polymers. And so what we do is we have CO2 and water in the atmosphere around us – the CO2’s increasing all the time, half the problem – and trees capture both of those through photosynthesis and then trees make sugar, essentially. And then the microbes come along and say, “Yum, sugar, I’ll store up my energy for later so I make these bioplastics.” And then what we do is we take those bioplastics out of the microbes, and we make our substitute plastic materials. And then the advantage is, because microbes make them, they can also degrade them, because they’re used to reusing them the way we use glycogen and plants use starch. And so the microbes can come along and degrade them right back to CO2 and water, which the tree can capture again and we can go round and round in that cycle.

Acknowledgements

Video excerpt from Science and the Plastics Problem, directed by Shirley Horrocks and produced by Point of View Productions.