From Judy Weleminsky - blog no 2
My initial training was with BCG – the live vaccine, which is used to inoculate mostly young people. It can be grown in a containment level 2 lab which has some biosecurity and is suitable for moderate hazards but not too high as it is not dangerous to humans. BCG is an attenuated version of Bovine TB.
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| pippettes |
While I was trying to get my head around sterile techniques, using pipettes, calculating and measuring small amounts, using petri dishes, making the growing mediums used in the lab, and awaiting the time when my skills would be considered sufficient to work with live mycobacteria tuberculosis, I also wanted to make a start on the first steps in my research. So, I persuaded the lab to let me trial making growing medium according to Friedrich’s recipe.
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| Powder used for most culture medium |
The growing media
usually used in the lab is made from dry
chemicals. However, Friedrich was clear that this would not work for growing
mycobacteria tuberculosis over many years in the hope that it would produce the
biproduct – Tuberculomucin – which is the therapeutic substance. I found that
the idea of growing TB for long periods was completely against the grain of
current microbiological work. Most of the work in the lab involved growing the
bacteria for weeks not years!
However, I got permission to trial making growing
medium, starting with fresh minced beef. My professor thought about it and said
– I’m ok with a little cooking in the department! I bought some lean mince from
the local shop, assuming that this wasn’t something I could order through the
provisions ordering system in the lab!
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| Mince beef before autoclaving |
I soon found that working with real mince in a lab had its
own logistical difficulties. Despite the comment about cooking by the
professor, there are no cooking facilities in the lab. But there is an
autoclave which uses heat and steam to sterilise liquids and equipment and
therefore seemed a reasonable substitute for the instruction to boil the beef
for two hours. I got training in how to use it, but I found the glass bottles
which they use to contain the substance to be sterilised were very awkward containers
for putting mince beef in and ever more difficult for getting it out!
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| Autoclaved beef before and after straining |
And filtering the liquid to get a clear bouillon was also a challenge given the large quantities Iwas attempting to produce and the tiny paper filters which took an interminable time to use. Eventually, I worked out ways of doing things but it was quite a learning curve.
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| Filtered beef broth |
I needed to add a number of chemicals to my bouillon and
then adjust the pH to get it to 7.6 as specified by Friedrich and then
autoclave it again to make sure it was sterile. Nonetheless I still had
problems with bugs which weren’t supposed to be there.
