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This blog was designed for the Biomedical Technology students at the Durban University of Technology, in Durban, South Africa. It consists of short notes on aspects that I feel that my students grapple with, and aims to provide a better explanation than that they would receive in lectures. It is also a very personal blog, where I feel comfortable 'talking' to my students.

Please email me sherlien@dut.ac.za




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Tuesday, February 23, 2010

nitrate reduction test


the nitrate broths are inoculated with the organism and incubated aerobically, 18-24 hours at 37 degrees.
after removing from the incubator, add solution A and B (in that order, 5 drops each) to each tube. Wait for a few minutes for the colour to develop. A red colour indicates a positive reaction, i.e. reduction of nitrate to nitrite.
zinc is added to all negative tubes. Zinc is able to reduce nitrates to nitrites, therefore a development of a red colour here indicates a negative reaction.
the tube that still shows no colour change is..... wait for it........ positive for nitrate reduction.
why you ask??????????
simply silly
because the organism reduced nitrates to ammonia gas. You could try smelling it to be sure, but I wouldn't advise it. Apart from fainting and becoming a hazard on the floor, (it's nasty down there), I can't see myself picking you up. Duh!!!!

isn't all this stuff amaaaazing!!!!

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