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August 16, 2019

Bruce RittmannThe Swette Center for Sustainable Food Systems focuses on innovative ideas and solutions to the many challenges of current food systems. In this series, we’re sitting down with the Swette Center affiliated faculty to catch up on food systems, innovation and what makes a good meal. See the rest of the series on our Food Systems Profiles page.

Read on for an interview with Bruce Rittman, director of Biodesign Swette Center for Environmental Biotechnology.

Question: How did you get interested in food systems issues?

Answer: My degrees are in civil and environmental engineering, and using microbial systems is a longstanding tool for environmental engineers. I decided to get a Ph.D and was very fortunate to work with the world’s leading person in the environmental microbiology, Professor Perry McCarty. That got me into the microbiology side of engineering.

Early in my career, there were all these new genomics tools that suddenly became available, and I was one of the first environmental engineers to get to work with these. Now there’s this huge field of genomics and other tools that have expanded our ability to do research.

Back when I was a student, it was very hard to do microbe research. We had good ideas but we couldn't implement them very well, but now we have the tools to study these organisms. We can use that knowledge to good purpose, like reducing waste and environmental harm in the food system. This is core to what we do here at the Swette Center for Biotechnology – get microorganisms to capture the value from things like animal and human waste.

Q: Share a glimpse of your current research and how it applies to food systems transformation.

A: I’m interested in food systems in two very different ways. On one side, I’m interested in the things that get lost, the residuals, from fields, to animals, to people. We lose most of what we apply on agricultural fields. Look at phosphorus – only 16% of the phosphorus applied makes it to the food we eat. The rest is runoff from the fields, or it ends up in animal waste or food processing waste. That’s a lot of loss. I’m very interested in mitigating those losses and recycling the phosphorus.

Sometimes that phosphorus comes along with a lot of organic material – animal waste, particularly from pigs and cows, or human waste, and some from food processing waste as well. That’s actually a good situation because all of that organic material contains a lot of energy that we can recover. And that’s what we do here at the Center.

Microbial systems can take this noxious organic stuff and convert that energy into something useful for human society. That cleans up pollution and it has economic value. We can make methane, hydrogen, or electrical power. And when we’re getting microorganisms to capture energy they release phosphorus and nitrogen, which can be recovered and reused in the agricultural system.

On the other side is the food that we eat, and another area of research here at the Center is understanding the role of microorganisms in the intestines and how that relates to human health. We’re trying to understanding the microorganisms in us, how they work, how they interact with us, and how our diet influences on the microbial community.

We’re working to design a “microbe enhancer” diet to help our microorganisms and intestines do better for themselves and for us. “Help the microorganisms help us,” that’s the philosophy for all of environmental technology. One of the things about the Western or American diet is that it starves microorganisms. The typical American diet is high in meat consumption, high in processed foods, lots of sugar, and really not a whole lot gets through to the intestines. We created a diet that ensures that there’s a steady supply of food for the microorganisms, with lots of fiber, less meat, and no processed food. The idea is to, “work for the microorganisms.”

Q: What’s an innovation in the food systems world that you’re excited about?

A: I’m excited about finding ways to capture the resources out of the things that we call “waste and residues.” How do we minimize runoff from the fields? We need to work with farmers and think about farming practices, and a whole host of other issues. It’s a very difficult problem. In a recent article we offered some ideas about how to manage diffuse phosphorus, and I’d love to see someone dig into it further.

This effort is just one outcome of a big international collaboration that was centered here at ASU and extended around the world. With funding from the NSF, we formed the Sustainable Phosphorus Alliance (SPA), to promote sustainable practices around phosphorus and the agricultural sector around that, particularly in North America.

For example, we decided to think about what it would take to cut the discharge of phosphorus into our waterways by 90%. Excess phosphorus causes eutrophication and hypoxia, and lots of other really bad things, so what would it take to reduce it?

We looked at where does the phosphorus go, and only 16% goes into the food and about half of that gets into our bodies. We did calculations about if we captured all the animal waste and treated it, and even if we were able to capture runoff, and still we couldn’t get to 90% assuming anything realistic. So how about if we change the diet? In our model, if everyone ate less meat, that put us over the 90% reduction. That’s the only way to get to 90% reduction of phosphorus in our waterways.

Q: What’s your favorite food?

A: I just love brussels sprouts. I haven’t done any research on the environmental impacts of growing brussels sprouts though, but I love them. I slice them in half, and then quickly sauté them with onions, garlic, olive oil.