An interview with Amy Pruden from Virginia Tech.  

Complete video interview can be seen here. 

Question: Can you tell us a little bit about how you became interested in the microbiology of the built environment?

Answer: I am trained as an environmental engineer, and environmental engineers work with all sorts of things; clean air, soil, water. I became focused on water. Now, my other graduate degree is in biology so it was just a natural attraction to me to look at the microbiology of water. In the past I have worked on things like remediation, using beneficial microbes to clean up spills, etc. Then I started learning about drinking water. Even though I am a microbiologist, even I wasn't aware that there is such a high level of diversity of microbes in drinking water. There is10⁷ or 10⁸ bacteria per liter and even I was surprised by that. The other thing I became aware of was that even though most of these bacteria are harmless, in developed countries where we have done a really good job of treating water, compared to developing countries, it's becoming the primary source of water borne disease outbreak are microbes that grow happily in drinking water systems.   So they view something like a shower head as a happy home. And so, I became interested in what I could do about that as both an environmental engineer and as a microbiologist.

Question: Can you tell us about the new Sloan Project that you just got funded?

Answer: Our project is going to focus on the microbiology of the building plumbing microbiome. The idea is to characterize the microbes that naturally colonize in the plumbing in peoples' homes and businesses. We are looking at things like what is the effect of the pipe material and what is the effect of the water chemistry. Every region of the country has slightly different water chemistry, and that can have a profound difference on the kinds of microbes found there. An interesting thing is that our water quality regulations tend to focus on the quality of water that comes out of the drinking water treatment plant and that is delivered to somebody's property line. I think we do a pretty good job of that, but we definitely have issues there that we have to work on. But there is the issue of the gap to the tap. The water that comes out of somebody's tap is a completely different quality than what is delivered to the property line. It's considered, legally, the homeowner's responsibility if there are pathogenic organisms growing in their homes. It is not the responsibility of the water utility company. But who is aware of this and what kind of guidance is there available? So we are hoping through our project to just first begin to understand what kinds of microbes naturally colonize the pipes and fixtures in peoples' homes. Then in our Sloan grant we are going to examine very controlled systems where we have replicates of pipe materials, water chemistry, flow rates and then that can hopefully give some guidance to people. What kinds of pipes are ideal? What kinds of flow regimes? Do you want a water saving feature where the flow is low? This has a lot of implication, too, as we start moving forward into water sustainability and green buildings.   This is a very important goal and we have to go after it but at the same time we have to go after it with our eyes open. A green building has a very different flow regime than a typical building.   The whole idea is to save water so that means water is sitting in the pipes longer and there is a lot more potential for microbial growth. I think if we can get a handle on what kinds of microbes live in building plumbing systems and what are the factors that control those microbes then we can also get a handle on how to address this issue of water borne disease outbreaks. Things like legionella, mycobacteria, and pseudomonas are things that grow in building plumbing systems and we don't understand the triggers. I think if we can dive deep into the microbiome we will get some ideas of what those triggers are and how to control them.

Question: Have you collected samples or analyzed any data yet?

Answer: We have officially been Sloan awardees for eighteen months, but we are off to a running start. We have been working with Mark Edwards who is a co-PI on the project and he has been working in building plumbing systems for years on the water chemistry side, especially things like lead and other contaminants that can get in the water. That's been a nice advantage to the project and brings an interdisciplinary angle. He has already developed these standardized rigs for doing research on building plumbing systems. These building plumbing systems are extremely complex with the pipe material, the flow rates, and the water chemistry. So, it is really important to have replicates and some sort of standardized system. So we have these standardized rigs installed at five utilities across the eastern portion of the country. They've already been out there and have aged for a year. That is important to get the microbiome established. We will be collecting samples over the next three weeks and then we will start extracting DNA and doing the sequencing on those.

Question: What is your favorite aspect or approach to studying the built environment?

Answer: The microbiologist in me thinks that this kind of science needs to be done. We need to know what's out there, what's in the building plumbing systems. That is the front line of microbes that we are being exposed to in our homes, for good or for bad. There is potential that there are beneficial ones, and I would like to know about those. But I think going about it in a very systematic and controlled way so we can get an idea of the factors that trigger the good microbes or the bad microbes.  

Question: What is one big scientific question in the study of the built environment?

Answer: I think definitely the issue of what triggers opportunistic pathogen outbreaks. There was an outbreak of legionnaires disease in a hotel in Chicago a few months ago and there was no idea what triggered that.   A new hotel in Las Vegas, a brand new building system so it not like it was deficient, again a legionella outbreak. So I think the big questions is, what is it that triggers those kinds of outbreaks?