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Dear blog and Blog readers,
Today in class we observed (what we thought would be) our final streak plate! To recap, this is what we discovered last class.
When we obtained the sample from the 30 degree incubator this is what we found:
Growth/cream/non-pigmentation
Since there was growth but no pigmentation and if this bacteria was the same bacteria as the red pigmented bacteria it should have become red in the 30 degree incubator we concluded that this cream/non-pigmented bacteria and the red bacteria are two different types of bacteria.
To further prove this statement, we created one last streak plate (a brand new one) from the pure soil sample.
The pure soil sample.
Our new streak plate.
We placed this streak plate in the 30 degree incubator to see what would occur one last time.
When we collected this streak plate today, this is what we found.
A pure sample of the bacteria obtained from the soil near the Ohio River in Steubenville, OH.
Dr. P advised us to prepare one more gram stain from this pure sample to see if we would still obtain the same result as we had before (which was mostly gram-negative bacteria.
Gram Stain 3rd 30 degree streak plate soil sample:
Max sterilizing the loop.
Max putting distilled water into the sterilized loop.
Max putting the water on the sterilized glass slide.
Sterilizing the loop once again.
Obtaining a pure sample of bacteria
Smearing the bacteria on the water droplet on the slide.
Allowing the sample to air dry.
We dropped crystal violet stain on the fixed smear for 20 seconds.
Rising the stain off with an indirect stream of DI water.
Then we covered the smear with Gram's Iodine for one minute.
We rinsed the slide with indirect DI water.
Next, we rinsed the slide at a 45 degree angle with 95% ethanol drop by drop until the color stopped
running.
Rising the stain off with an indirect stream of DI water.
Next we covered the smear with Gram's Safranin for one minute.
Rising the stain off with an indirect stream of DI water.
Finally, we blotted the water from the slide with bibulous paper.
Max focusing the microscope.
Observing the slide under the oil immersion lens.
Interestingly enough, we observed gram-positive bacteria with some variable bacteria. There appeared to be all circles (with two colors, purple and red) but some appeared as rods. Dr. P advised us to do one more gram stain next class.
Next, we were instructed to do a negative stain with the samples from the second, more pure test tube, "S2"(our unknown) and our pure soil bacteria sample.
S2- our test tube we created from the unknown tube Dr. P gave us last class.
The purpose of this view bacteria under a microscope with a dark background so that transparent cells are more easily seen, to make visible bacteria that is hard to stain or is changed by heat-fixation.
First we obtained two clean slides and labeled one "S2 N" to stand for S2 negative stain.
We placed a drop of Nigrosin on one end of the slide.
We sterilized the loop.
We then obtained a sample from the S2 test tube.
We smeared the bacteria into the Nigrasin.
Max then smeared the bacteria and Nigrosin across the slide.
We waited for it to air dry!
We prepared our second slide for the negative stain and labeled it "Soil N" for the pure soil sample
We placed a drop of Nigrosin on the slide.
Then we sterilized the loop.
We obtained a little bit of the bacteria from the pure soil sample.
Max then spread the Nigrosin and bacteria on the slide with another clean slide.
We then allowed it to air dry!
Before the end of class we were not able to properly view the slides under the oil immersion lens. Check back next time for the results!
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