In 2021, as the labs were opening up again post-COVID, we were lucky enough to host the science writer Tom Ireland in our labs. Tom was writing a book on phages and phage therapy and had heard about the Citizen Phage Library project. He got in touch and we sent him some sample jars and invited him down to process his samples.

As he describes in his book, the first set of samples yielded nothing. Not even a phage for E. coli. This was about the time we'd noticed that if samples were sat around for a while, we were less successful at isolating phages from them.

A quick and dirty analysis showed that for every day between collection and filtering of the samples by us in the lab, the log odds of recovering a phage dropped sharply. However, once they were filtered, the likelihood of phages being found in samples was stable for months.

We put this down to phages adsorbing onto particulates and thus being filtered out with the bacteria when we processed the samples. This prompted us to redesign the sampling kits to use syringes rather than glass jars, with filters attached so that the samples could be filtered during sampling. Tom was one of the first people to receive these new kits for a second attempt at sampling, and we were delighted that in the second batch we found two phages against Pseudomonas aeruginosa (which he named Emmi22 and PixBrook) and one against E. coli (called PCSewage).

If you want to read more about phage therapy, I can highly recommend Tom's book! It's a great read and has great reviews.