Phage Hunting: The two sides

by Peter Kalugin

I chose the phage hunting class because I wanted to learn more about biology. I was looking for a cool experience in a new setting. Yet, over the past few weeks, phage hunting has seemed more and more like an experience I have already had and do not remember fondly – frustration.

Hunting phages is not an easy task. Sam (my talented lab partner) and I spent weeks scouring the lands of the Hopkins campus for soil. Tube after conical tube was wasted as our direct platings and enrichments returned nothing but plates of healthy M. smegmatis. When we finally had phages, they were from an enrichment of compost donated to us by Dr. Schildbach. Though we were overjoyed to have finally succeeded, and adopted this phage (code named BOSS) as our own, there was still an iota of disappointment. We continued to collect samples and plated enrichments on the side, but without hope. But when we finally decided to stop this seemingly pointless search, our last three tubes yielded a huge number of phages! One set of enrichments (Final BOSS) was quickly adopted out to John, and has been very successful. After streaking, the other two sets yielded three different kinds of phages (The BOSS, BOSS X1 and X2). Ecstatic is not a good enough word to describe how we felt – we went from one phage to four in a week’s time, and were consistently escaping the common setback of contamination. We kept up this momentum for several weeks – we streaked and plated dilutions to calculate titers.

But, as all good things, this success had to come to an end. We were finally hit with contamination. Then our phages wouldn’t grow and we had to harvest new lysates. Then more contamination. We used to walk into lab with smiles on our faces and cheerfully talked about our phages outside of class – now, this was a closed topic. It felt more and more like a dead end, more and more like a waste of time. Streaking and filtering the lysates did not help – contamination kept returning, both from other bacteria and foreign phages. Perseverance remained, but enthusiasm slowly started drifting away.

We came to the conclusion that four phages were too many for us to take care of – BOSS X1 and, even more sadly, our original BOSS had to be put on hold. I continued searching for a web plate for BOSS X2 and finally, just this last weekend, I had a breakthrough – a perfect web plate from a 10-5 dilution of my poor doubly filtered lysate. I have since plated 10 of these web plates, and they all turned out very well – I was able to harvest my high-titer lysate and will finally get to meet my phage this Friday when I take a sample to the electron microscope facility. Hopefully I can finally get on the right track again after the horrible last two weeks.

Throughout this, I have learned an important thing – phage hunting is not for everyone. It is not for the faint of heart, for those that fear failure and quickly lose hope. Phage hunting takes guts. Luckily, my classmates and I have shown ourselves to have that. But for the aspiring phage hunters here is my question – are you up to the challenge?

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