This semester students plated 10 ml of lysate from a clean enrichment protocol, 2 ml per plate.  The results are promising- 3 students had cleared plates, 1 had a definite web and only 6 started a new sample today, everyone else was checking putative plaques.  We will see how many actually passage.  This is in contrast to last year where we screen enrichments on spot plates or did plaque assays with 50µl.

Lab chaos begins because some are repeating, some are spotting, and some are trying to figure out what to dilute and replate.

We are also increasing the amount of metadata that we collect on the soils.  Today we introduced pH, %water, and %sand,silt,clay.

A couple of problems- the Arthro culture from Sunday night is foamy and clear, so we used last week’s culture which had been stored in the refrigerator.

We checked the culture with a spot test that is in the C353 lab.  I also started a new culture from the 5ml tube from Friday.

One change we tried today on soil samples #2- the spin before filtering was 6kxg instead of 3kxg.  It was much easier to filter!  Next time we might try 6k for 5 min.

Also, several instances of top agar sliding.  This may be because you were rushing the process, but more likely it is because the plates were “wetter” than usual.  They were stored in the boxes at room temp with the lid on when I came to lab.  Also, there may have been a small dilution error- if you added 0.5ml of culture to 4ml of the  1X solution.

A bit of confusion on the broth components.  It is best to leave the Calcium out of the stock solutions so they don’t cloud up and so students can determine the amount they want to experiment with.

On parafilming…this is not necessary if the plates are going to be kept in a closed box in the fridge.

Chris F began checking on micropipetting skills.