Mutant Bacteria Strain?? Antibiotic Test Results and Bacteria J Revealed!!

Mutant Bacteria Strain?? Antibiotic Test Results and Bacteria J Revealed!!

Class: November 21, 2013

A few class ago, Dr. P demonstrated UV radiation use in killing bacteria.  (Remember the light saber??) It supposedly kills EVERYTHING (even spores!), but we wanted to know just how effective the UV light, so we grew three spread plates, one before the UV treatment, one after the first treatment, and another after the second treatment.  You'd think it would be pretty effective after TWO treatments, right? WRONG.  The pre-treatment plate was of course the worst, but there was a pretty gruesome amount of bacteria growing on the first post-treatment plate, and even more on the second!! This made no sense, so we pursued it further and infected some DiH water with this particular bacteria, did the UV light treatment again, and made another spread plate.  Before treating the water, we cleaned the SteriPen tip with alcohol and did a spread plate of that, just to be sure it wasn't an alcohol resistant bacteria on the tip of the pen.  We have the results today, and they are pretty interesting.  There were zero bacterial colonies on the alcohol-sterilized-tip spread plate...

It is a little difficult to see, but take my word for it
there are nada bacteria on this spread plate!

However, there were 3 very small colonies growing after treating the water (it was treated one time).  So, it would seem that we have a bacteria on our hands that is resistant to UV radiation. Rare for sure.  

Last week we created a spread plate of Bacteria J and placed various antibiotic discs on it, which we sectioned off and labeled:

When assessing bacterial effectiveness, we measure the circumference of clear space around the antibiotic disc.  The greater the circumference, the more effective that particular antibiotic is.  Here's our line up:

• Novobiocin- 5.3 cm
• Erythromiocin- 4.6 cm
• Neomyocin- 1.4 cm
• Tetracyclin- 3.5cm 
• Penacillin- 2cm

The winner clearly is Novobiocin, the least effective being Neomyocin.  We conducted this test to further support our current findings about Bacteria J, namely that it is a Gram-positive bacteria.  We know that Gram positive bacteria have peptidoglycin in their cell membrane in large quantities, so different antibiotics are more effective then others, depending on the bacterial structure they target.  Novobiocin is a DNA synthesis inhibitor, which is greatly effective across a broad spectrum of bacteria.  Erythromiocin and Tetracyclin are both cell wall-targeting antibiotics, so it makes sense that they were both fairly effective in killing Bacteria J.  It's awesome when your test results support the rest of your research :)

ATTENTION PLEASE. IMPORTANT ANNOUNCEMENT: MYSTERY BACTERIA REVEALED!

After a semester of careful testing, staining, spreading, microscopic viewing, and being disappointed by almost all the results, we finally nailed down who Bacteria J is! World, meet Micrococcus Roseus: 

Around here, we like to call her Rosie.  Especially Matt.  He's really fond of her.  In order to track down exactly what species of bacteria this was, Dr. P. gave us a few flow charts with various classifications of bacteria on it, that compiled also the test results.  We followed the flow chart for gram-positive coccus bacteria, and almost chose Micrococcus Leteus, but upon further research we found that Micrococcus Roseus was nearly identical in reaction and morphology, except that it is pink, the exact description of our very own Bacteria J :) Team, well done. 

Let's celebrate with a little lab-made yogurt shall we?

It was probably the best yogurt I've ever had.  No joke.