Part II: In our last episode, I was sent some fig trees from Florida
that had galls on them. In this episode, I examine them with the help
of an expert.

The samples were Fed-Ex'ed and arrived last Friday in beautiful shape.
This is especially important with bacteria; if the samples get old,
other bacteria begin to invade the tissue, and you can't tell which was
there to begin with.

I agreed to take the samples because my friend Fari is a bacteriologist
and I knew he'd help me. Fari was a professor in Iran and when the
Shah fell, he fled to the US to keep his son safe (otherwise he'd have
been drafted into the Iranian army). Fari had a hard time finding a
proper job, and for a while he worked on a turkey farm, and then for a
corporate plant-care company (the people who put the weeping figs in
the lobby, and the poinsettias by the elevator at Christmas).
Eventually he got a job at the USDA, where he brings great joy to
everyone who works here!

Anyway, he and I unpacked the box, and we were both sure the galls were
caused by the crown gall bacterium (look at the picture on the gallery-
those swollen warty nodules are characteristic). Fari said when he
worked for the plant-care company he saw hundreds of figs with crown
gall, and they looked just like this. Still, we had to be sure. The
first step was to try to isolate the bacterium. Although the galls
have quite a lot of volume, the bacterium is found just under the
surface, not inside it, so Fari used a sterile razor blade to pare off
the rind (which was not sterile), then sliced off a piece just under
the surface of the gall. He put the tissue in a sterile petri dish in
a few drops of sterile water and teased the tissue apart to release the
bacteria. After waiting for half an hour, he took some of the water
and streaked it on a plate of nutrient media.

On Monday I checked the plates and they were dotted with little white
convex colonies of bacteria. They looked like Agrobacterium, but were
they?

Stay tuned for our next episode!