If you add 10x too much antibiotic your bacteria will never grow – Wednesday 21st Oct It

Yesterday was a busy, but unproductive blur. I arrived at 8:30am, I meant to leave at 5pm but I didn’t leave until 6pm. I did manage to fit in a nice lunch out with the boss and our soon-to-graduate Master’s student and at 6pm I went to the gym even though it was a little later than planned.

Today, I arrived at 8:30am and was in the lab by 9am. I set up PCRs and the mutants I’d made had grown on the antibiotic media (meaning they were real mutants 🙂 ) so I set up cultures to grow them up and store them. I added antibiotics to my media to make sure that only cells with my mutation were able to grow, but apparently this morning I was a little tired. It wasn’t until about 2pm, when they still hadn’t grown, that I re-did my calculations and realised I’d added 10x too much. 2000ug/ml rather than 200ug/ml. Even bacteria with an antibiotic resistance cassette were going to struggle with that much antibiotic. Luckily I don’t tend to throw plates away until the end of the day so I still had some cells on an agar plate. I set up new cultures to incubate (with the right amount of antibiotic!) and as a backup also streaked some of the left over cells onto a fresh agar plate.

About 11am I found out I’ll have 246 samples arriving on Friday, so I had the pleasure of making enough media for 300 plates. I checked with the kitchen staff and as long as I get it too them before 10:30am tomorrow they are happy to autoclave (sterillise) it for me in their big autoclave. Today I weighed out media for 15x400ml bottles of agar, tomorrow I’ll add water, autoclave them and pour all 300 – tomorrow will be fun.

I had an early lunch at 12pm with a friend, we went to the students union for pizza 🙂 . I was back by 12:30pm which left me loads of time before my demonstrator briefing at 2:30pm. It was somewhere in here when I realised the antibiotic mistake and went about fixing it. 2:30-3pm I had a demonstrator briefing before tomorrows practical. Through the day my undergrad managed to work fairly independently, so that was a definite step forward. He did manage to waste a fair amount of DNA, but more of that can be made so that’s not the end of the world.

Between 3-4:30pm I did some lab work (mostly fixing stuff) and also put together some graphs for the boss. At 4:30pm I sat down with him and the graphs, and we tried to draw some conclusions. I won’t say we were entirely successful, but it was a useful discussion. We chatted until 5pm when I went off to Pilates. After a lovely, relaxing hour I went back to the lab and frozen down the rescued mutants. It was then that I realised I’d completely forgotten about a gel I’d been running 😦 . It’d been going for about 2.5hrs, so I really wasn’t hopeful I’d see anything, and I was right. All my DNA had run all the way through the gel and right off the other end.

So that was my less than spectacular day, filled with mistakes, but they’re fixable so all I’ve lost is a little time. Tomorrow is a new (hopefully more productive) day, so until then everyone, thank you for reading.

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