 We are feeding them with seaweed sugars. So once we have a lot of microbes inside our fermenters and they are full of PHAs inside them, we can extract that PHA and then really process it just like the plastic. But they remain truly biodegradable. Dr Julia Heisser. Could there be a day in the future where a seaweed-based material replaces single-use plastics? We'll have to wait and see.