Staving off a massive diatom culling

At the end of last semester, chaos tore through my portion of the laboratory when a massive die-off of diatom cultures was a major possibility.

My diatom cultures have been growing in glass test tubes with liquid media, within which they're happy for an upwards of three weeks before they need to be transferred to fresh media. There are a number of factors which make culturing my individual lines of diatoms different from our various stock cultures of diatoms that also grow in the culture room, so it's been a bit of a change for me.

With a few weeks left in the semester, I inoculated two large cultures for my final experimental assay. After about five days, there seemed to be almost no growth, but I figured I'd give them a few more days. After a week I told myself I must have messed up somehow, so I inoculated two more large cultures and I was on my way. At about this time, I made some solid media plates and spread all 40+ of my cultures on individual plates to preserve them while I was away on holiday. (The solid media plates combine the sea water/nutritional supplements I usually grow the diatoms in with agar to solidify the mixture. This is essentially the diatom version of the plates I used to grow my bacteria on when I was cloning DNA.)

But then the second round of large cultures didn't growth either. (Meanwhile my plates still had another 5+ days to show any signs of growth.)

...Yeah... It was at this point I went into a deep panic because my diatoms in my test tubes were dying off and it came to my attention that the materials I was using to supplement my media (i.e. the nutrients to sustain growth) were, well, bad. (This is what happens when I'm not responsible for all of my materials. I am not attacking anyone, but when things matter in the lab I should really do everything myself like make the materials needed for my cultures.) This meant the plates I had made using these materials would not sustain any growth and all of those plates would have to be thrown away.

Now I was upset for multiple reasons: I lost a full day's worth of tedious lab work setting up my first 40 plates and all of my diatom lines were thinking about kicking the bucket.

GREAT.

Additionally, I didn't get in my final experimental assay because my diatoms kept dying in the large cultures due to poor nutritional content.


The end of the semester resulted in frantically making new plates with different materials and pleading with the science gods that they grew while I was away at home.

(Insert a lot of World of Warcraft playing at home)

After a week in the hills of Vermont and New Hampshire, I checked back into lab before heading off to Florida. Thankfully, almost all of my plates showed signs of life which meant I could catch my plane without fretting about my meager diatom cultures.

Attempting to save all of my discrete diatom lines.

After I got back from Florida a week later (roughly two weeks after the second plating), it was time to check on my plates once again.

This time I wasn't as happy with what I saw. Because I was hasty in finishing my plating before I left for home, I did sort of a good-enough-but-crude job. While some of my plates may still be good and support/sustain healthy cultures after they dry off some extra moisture from the initial plating (I sealed each plate to prevent them from drying out), I decided to transfer each culture back to new test tube cultures. I ended up using a combination of plated cultures (two weeks old), old liquid cultures (one month old), and really old liquid cultures (two months old), to sustain almost every line I started with. There are still a few lines I may be able to salvage from my plates
 

A majority of my massive diatom culture collection.

This has been an interesting experience for me and I still have a few things to learn and figure out. The tricky part is that I don't have a lot of spare lab time to tinker around and perfect everything. But because I like everything to be done right, I'll figure them out. First and foremost, I'd like to plate my diatoms so they can subsist for at least three months without me tending to them. While it will be a fair amount of work invested at the beginning of the process, it will save me heaps of time in the long run because I won't have to cater to the high-maintenance demands of my diatoms.

Once I settle back into my hectic life. I hope to consolidate all of my diatom cultures for long-time storage and press onwards to finishing my project for once and for all.