The last day of the Small World Initiative at Yale my roommate and I walked down to the UPS store and shipped a few streak plates home. They were to arrive on a Thursday, the day I had to drive down to San Diego for a couple of meetings, and then I was leaving town on Friday. I asked the labtech to put the plates in the fridge.

I completely forgot that the little box was not labeled anything special, and as normal mail it was lovingly placed on my chair in the office. When I returned to campus the Tuesday after, I started opening the box with apprehension. “It will smell bad,” announced to the labtech as I started opening ziplock bags. “One of them seems to be a Pseudomonas.” Indeed, when the last bag was opened, the musky smell of earthiness surrounded us. However, the babies looked ok. The colonies were big and fat, but the plates were not overgrown.

That same day the 16s sequences had arrived via email, and after a quick Blast, the predictions based on Gram staining and colony morphology were confirmed. One was a Pseudomonas, the other a Bacillus.


Inhibition zone on the E.coli spread plate around one of the colonies. Broken agar, my bad. Ugly lawn too.

With a microbiology course happening on campus, I looked for bad bugs to test, and found E.coli and Staph. aureus. I did a quick spread/patch plate with the 2 candidates. Today the Pseudomonas was showing a clear inhibition zone with E.coli, and a possible one with the Staph.

So this is exciting, although hardly earth-shattering. As an anthropocentric cell biologist (mea culpa, mea culpa) I knew a lot about antibiotic resistant nasty bugs such as P.aeruginosa, but I just realized there are a lots of other Pseudomonas in the soil that have to do with protection of plants from diseases. And those antibiotics are of the phenazine type. I just got started in the literature research, so I do not know much more, apologies.

That said, I do want to finish the SWI sequence, so next time it will be testing against the whole battery of ESKAPEs, and starting some traditional microbiology. Where is a Bergey’s when you need it?

I know it is not P. aeruginosa, as even when spread on a P agar it was not green. And I don’t think it is P. fluorescens because it does not fluoresce under UV light. Grateful for your advice as to how to proceed.

The other baby, the Bacillus, did not do squat to E.coli.

Still love them both. What do microbiologists say? “You get attached to your bugs.”

Amen to that!