Q&A with Dr. Molly Morse of Mango Materials on methane based bioplastic

Posted by Chandler Slavin on Jul 14, 2015 3:15:00 PM

Hey guys!

I hope everyone had an awesome 4th of July weekend. 

At SUSTPACK15 in Orlando this Spring I watched a presentation from Dr. Molly Morse, CEO & Co-Founder of Mango Materials, a producer of methane-based PHA plastic. 

Having researched the available bio-based/biodegradable/compostable plastics on the market since becoming Dordan's Sustainability Coordinator in 2009, I was interested in this development in PHA production. Dordan had sampled PHA supplied by Mirel Bioplastics a couple of years ago, including it in our bio resin show N Tell, but never produced PHA thermoform packaging because the material was too expensive. PHA is interesting because it can biodegrade in any end of life environment, be it home compost piles, waterways, etc. This contrasts with PLA, which is made from polylactic acid, because it can only biodegrade in an industrial composting facility. 

After briefly meeting Molly I wanted to learn more. What follows is our Q&A:

Q: Molly, can you tell me a bit about yourself and your history with Mango Materials?

A: I am a PhD graduate of Stanford University previously focused on environmentally friendly construction materials; materials and products that have a temporary use but can biodegrade at end of life, like disaster housing. The term here is "biocomposites," which is when you have a natural fiber and some kind of matrix material holding the natural fibers together. This interest in biocomposites led me to become interested in PHA as a potential matrix material because it can biodegrade in lots of environments. This was about 10 years ago when I was a Graduate student and PHA was historically expensive and hard to find as it was made using Ecoli and feeding them sugar. Instead of feeding the bacteria sugar, we wondered, could we feed them methane? This was the Ah Ha! moment for us.

Methane (CH4) --> PHA is organically favorable to sugar --> PHA; the process is quicker in that it is direct. It is what the bacteria want to do. With sugar you have to break down the chain and rebuild using energy. In our process we just build, which is obviously energy favorable. By changing the feedstock from sugar to methane it significantly drops the cost of production. 

Q: Can you clarify the difference between PLA and PHA?

PHA is naturally occurring (bacteria naturally produce it), while PLA is synthetic. 

Q: If PLA is "synthetic," why is it called a "bioplastic?"

A: Something is considered a bioplastic if the carbon is derived from a "rapidly renewable" resource (like sugar, corn, starch), as opposed to ancient fossil fuel carbon. This does not guarantee biodegradability, however. The PlantBottle is an example of a bioplastic that is not biodegradable. The carbon that make up the PET polymer of the PlantBottle are from sugar, not fossil fuel, and the PET "chain" is chemically and stucturally identical to fossil fuel based PET; and as such, it can't biodegrade. PLA is made from sugar/starch that will break down in an industrial managed composting facility. So you can use fossil carbon to make biodegradable plastics and "rapidly renewable" carbon to make non-biodegradable bioplastic. These are both called bioplastics. 

PHA on the other hand will biodegrade with enzymes found in the environment; it is "bacteria fat" and will break down in the ocean; you can eat PHA. 

Q: How does PLA compare to PHA in the context of packaging applications?

A: PLA has a lower melt point than PHA. Heat makes it degrade. That means that PLA plastic cups at a picnic can begin to melt if exposed to too much heat; I believe this has been drastically improved by Natureworks, however. PHA by comparison doesn't have this problem; a PHA straw won't turn into spaghetti in your coffee cup. 

Q: How would methane gas from landfills be captured for conversion to PHA?

We partner with a methane producer. Right now we are focused on the methane from water treatment plants; this is a common source of methane. But we are interested to partner with any methane producer: landfills, agricultural facilities, extinct coalmines, natural gas, etc.

All methane sources are a little different. While we can use any form of methane (landfill methane vs. water treatment methane), what we really need is the methane component of the gas (CH4). 

The methane gas is already in pipes from the water treatment plants, which we pipe directly into our fermentation system. There are bacteria inside the fermentation system that have been selected specially because they naturally eat methane to grow. They eat the methane and inside the cell walls they produce PHA biopolymer. This process is naturally occurring like how humans eat food and store it as fat. 

Q: How do you get the PHA out from inside the bacteria cell walls?

We are working on separation techniques, and have been for 4 years. It's a big deal how you separate out the cell from the PHA; ours is a trade secret. 

The PHA comes out essentially as a powder, which we extrude and pelletize. It is white. 

Q: What is the waste product from this process?

Heat is the biggest waste from the bacteria we use to make PHA. This can obviously be repurposed to power some onsite manufacturer. The other main waste is the biomass content; that is, what is left over after you separate the cell mass from PHA. We see this as a potential liability in our economic model. 

Q: What is the ratio of cell bio mass waste to PHA?

About 30-40% by weight of starting cell mass becomes PHA. 

Q: Can you tell me more about Mango Materials' relationship with Stanford?

This technology was developed by a whole team of people working and studying at Stanford over about 10 years. Mango Materials has licensed this technology from Stanford; we have the exclusive rights to commercialize this technology. After I got my PhD I consulted and ended up going back to Stanford and licensing the technology. We incorporated in 2010 and we received our first grant in 2011. After the Ah Ha! moment I looked exclusively at PHA and did my PhD on how PHA breaks down. 

Q: What is the market for this material? 

We produce pellets that others convert into something like extruded sheet for thermoforming. What we are really interested in are applications where there is no good end of life option for the material, where it can't be recycled. Agricultural sheets, for instance, or any product that ends up in marine environments like crab traps, or fishing nets. We are targeting markets where the end of life isn't recycling. 

Q: What is the timeline for commercialization?

We are excited about our first application, which is micro beads that are found in face washes and historically made from plastic. These micro beads enter the waterways and don't breakdown. We are very close to commercializing this. 

Q: Do you see application with packaging?

Yes, but it depends on the funding. Currently we are a single track focused on micro beads vs. double tracking on packaging and micro beads. We intend to produce films, however, and provide to converters for trial runs. The packaging we would be focused on would be food packaging that is contaminated by food waste and therefore unable to be recycled but can piggy back on the industrial composting supply chain. 

Q: Have you conducted a formal LCA of your PHA from cradle to gate?

We have conducted internal LCAs but nothing published for review. Ours show that our PHA is carbon negative. 

To learn more about Mango Materials, visit


Pictured: Dr. Molly Morse

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