We’d like to share an update from Matthew Gebert (from the return envelope) on the Showerhead Microbiome Project. It’s been a few weeks since you last heard from us (thank you for your patience), but the project has been moving along quickly! As of February 2017, we have sent out around 1,200 sampling kits across the United States and 300 kits in Europe (we can still use more European participants)! A huge thank you to everyone who has participated and sent back a sample in the last 6 months. If you haven’t returned your kit yet, we would love to see it in our mailbox soon! Now is the time to swab your showerhead, collect some data, and send everything back to Colorado.

In November 2016, we took the first 186 submitted samples to arrive in Colorado and began the many-stepped process of determining what lives in the slime therein. Great news! We found an abundance of life in the slime, many individual organisms of many different species! Well, it seems like great news to us anyway.

On the basis of our initial analyses, we generated a map showing the abundances of Mycobacteria in each participant’s showerhead. The Mycobacteria are a diverse group of bacteria (hundreds of species) that can be very abundant in showerheads. Many of these mycobacteria are harmless, some are capable of causing respiratory disease (non-tuberculous mycobacterial infections) and some may actually be beneficial and able to improve the immune health of those people exposed to them. Thus, the presence of mycobacterium in your showerhead does NOT mean you are at a greater risk for respiratory infection  and one should NOT begin to panic upon reading this post.

We are beginning to see some patterns in which homes have more Mycobacterium and which have less. Notice the variation from point to point on the map. The darker the point on the graph, the higher the abundance of Mycobacteria in the shower head sample.

One of the goals of this project is to understand the diversity and ecology of those bacteria living in our showerheads, why some homes have far more individual Mycobacteria cells than others, but also more Mycobacteria species, and what that might mean for human health.We want to know not only how many Mycobacterium are in a showerhead, but also which Mycobacterium.

We have also begun to consider differences in the chemistry of the water in participants’  homes. The graphs (below) of water chemistry are still rough and ready (our equivalent of the paper napkin sketch) because our work is still very much in process (and for this first sequencing step of the project I’m the one doing most of the work and I actually have to sleep sometimes, though Noah did put a pillow in the lab so that makes things easier). What we see most clearly in the data on water chemistry is that the water in shower heads varies from place to place. The acidity of the water (pH), varies  from 6.2 all the way up to 8.5, though most of people have water with a pH of around 6.2). Water hardness, chlorine concentrations and iron concentrations also vary from sample to sample. All of these attributes of tap water have been suggested to influence which microbes survive in the water.

We haven’t had a chance yet to compare the bacteria in the water samples to the chemistry of the water (and we will probably wait to do so until we know not only how much Mycobacterium is in each sample, but also which species and which other microbes as well). We have, however, compared the Mycobacterium present in homes with well water versus those with municipal (city) water. Here we see a huge difference, many more individual Mycobacterium in houses with city water.  You must remember though that this is still a pretty small data set, so these are just preliminary results. Also, just because the source of your water is municipal, you are not at elevated risk for any sort of disease or infection (No one needs to start digging a well…)

Thank you again to everyone who has sent back their kit! We appreciate it tremendously. We feel like we are at the beginning of resolving a grand series of mysteries (and opening up new mysteries). It is an exciting time in our lab. If you still have your kit, or will be receiving it in the mail soon, now’s the time to sample and send them back as soon as possible!

Check back here soon for more updates on what we’ve been finding from our explorations of the microbial life in your showerhead.

This has been a guest post by Matthew Gebert. Matt is a research technician in the Fierer Laboratory at CIRES, at the University of Colorado – Boulder where his research focus is on The Showerhead Microbiome Project. He declines to say how much Mycobacterium is in his shower head.