Tuesday, September 10th 2013

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Class Date: Tuesday, September 10th 2013

Dear blog and blog readers,

In microbiology class on September 10th we were able to see the results of our three streak plates.

In turns out that our hypothesis was not correct.

The streak plate that was placed in the 25 degree incubator grew plenty of bacteria, but the red pigment was inhibited.

The streak plate that was placed in the 30 degree incubator grew a decent amount of the red pigmented bacteria as our previous streak plate had, but the culture was purer this time.

The streak plate that was placed in the 37 degree incubator had almost no bacteria growing.

Our conclusion is that this bacteria grows best in the temperature of its natural envrironment (30 degrees Celius). When it becomes cooler than that, such as in the 25 degrees Celsius environment, the red pigment is inhibited. Lastly, when it becomes much warmer than 30 degrees Celsius, such as in the 37 degree incubator, bacteria growth is almost completely inhibited.

Under the direction of Dr. P we placed the streak plate that had been in the 30 degree incubator (red pigment) in the 25 degree incubator and the streak plate that had been in the 25 degree incubator (cream pigment) in the 30 degree incubator. At this point we hypothesized that when they switched incubators they would switch pigments as well. We did this in an attempt to see if this was truly the same bacteria.

The next thing we did was attempt to stain this bacteria so as to later identify it under the microscope.


Preparing a smear...

First, we obtained a sterilized glass slide, and labeled our sample slide. Next, we sterilized the loop and placed a small droplet of distilled water on the slide.

Our sterilized glass slide labeled "soil" with Max placing a droplet of distilled water in the sterilized loop onto the slide. 

 After we placed the water on the slide, we sterilized the loop again, and from our second streak plate from the 30 degree incubator, we collected a small culture of the red pigmented bacteria.

Using the newly sterilized loop to collect a pure sample of the red bacteria. 

We then spread it around on the drop of water on the glass slide.

We allowed it to air dry.

We sterilized the loop once again. Once it was dry, we passed the slide quickly through the flame three times with the smear side up in order to "heat fix" it.

Note: We prepared a fixed smear on two slides. However, on one slide, we did not continue on to stain the slide due to the prior red pigmentation. We were curious as to whether or not the natural pigment would act as a stain.

Both of the slides air drying.

We first took a look at what we could see with the unstained slide under the microscope.

Our unstained slide under the oil immersion lens. 

Sam attempting to focus the microscope. 

The unstained red soil bacteria under the microscope. 

Staining...

 We placed the heat fixed slide (the one we intended to stain) over the sink and then covered it with several drops of methylene blue stain for one minute. 

After one minute had passed, we rinsed the slide with an indirect stream of distilled water. 

We plotted excess water from the slide with peices of bibulous paper. 

We examined this slide under the oil immersion lens.

Placing the oil on the slide. 

Focusing the microscope. 

Max observing the bacteria. 

Images of the bacteria that exhibited a natural red pigment after having been stained blue

 Both the stained and unstained slides appeared to show an almost equal degree of pigment, although the stained slide clearly had a higher degree of pigment.